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UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

______________________________

FORM 10-Q

______________________________

(Mark One)

☒			QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

For the quarterly period ended June 30, 2020

Or

☐			TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

For the transition period from              to             

Commission file number 1-10706

____________________________________________________________________________________

Comerica Incorporated

(Exact name of registrant as specified in its charter)

___________________________________________________________________________________

Delaware			38-1998421
(State or other jurisdiction of incorporation or organization)			(I.R.S. Employer Identification No.)

Comerica Bank Tower

1717 Main Street, MC 6404

Dallas, Texas 75201

(Address of principal executive offices)

(Zip Code)

(214) 462-6831

(Registrant’s telephone number, including area code) 

_________________________________________________________________________

Securities registered pursuant to Section 12(b) of the Act:

Title of each class			Trading symbol			Name of each exchange on which registered
Common Stock, $5 par value			CMA			New York Stock Exchange

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days. Yes ý No o

Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S-T (§ 232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit such files). Yes ý No o

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company, or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company,” and "emerging growth company" in Rule 12b-2 of the Exchange Act.

Large accelerated filer			☒			Accelerated filer			☐
Non-accelerated filer			☐			Smaller reporting company			☐
Emerging growth company			☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. o

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act). Yes ☐ No ☒

Indicate the number of shares outstanding of each of the issuer's classes of common stock, as of the latest practicable date.

$5 par value common stock:

Outstanding as of July 27, 2020: 139,039,348 shares

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Table of Contents

COMERICA INCORPORATED AND SUBSIDIARIES

TABLE OF CONTENTS

PART I. FINANCIAL INFORMATION
ITEM 1. Financial Statements
Consolidated Balance Sheets at June 30, 2020 (unaudited) and December 31, 2019			1
Consolidated Statements of Comprehensive Income for the Three and Six Months Ended June 30, 2020 and 2019 (unaudited)			2
Consolidated Statements of Changes in Shareholders’ Equity for the Three and Six Months Ended June 30, 2020 and 2019 (unaudited)			3
Consolidated Statements of Cash Flows for the Six Months Ended June 30, 2020 and 2019 (unaudited)			4
Notes to Consolidated Financial Statements (unaudited)			5
ITEM 2. Management’s Discussion and Analysis of Financial Condition and Results of Operations			35
ITEM 3. Quantitative and Qualitative Disclosures about Market Risk			65
ITEM 4. Controls and Procedures			65
PART II. OTHER INFORMATION
ITEM 1. Legal Proceedings			65
ITEM 1A. Risk Factors			65
ITEM 2. Unregistered Sales of Equity Securities and Use of Proceeds			66
ITEM 6. Exhibits			67
Signature			68

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Table of Contents

Part I. FINANCIAL INFORMATION

Item 1. Financial Statements

CONSOLIDATED BALANCE SHEETS

Comerica Incorporated and Subsidiaries

(in millions, except share data)			June 30, 2020						December 31, 2019
			(unaudited)
ASSETS
Cash and due from banks			$	1,048					$	973
Interest-bearing deposits with banks			12,263						4,845
Other short-term investments			153						155
Investment securities available-for-sale			12,759						12,398
Commercial loans			33,826						31,473
Real estate construction loans			3,952						3,455
Commercial mortgage loans			9,925						9,559
Lease financing			589						588
International loans			1,104						1,009
Residential mortgage loans			1,886						1,845
Consumer loans			2,164						2,440
Total loans			53,446						50,369
Less allowance for loan losses			(1,007)						(637)
Net loans			52,439						49,732
Premises and equipment			450						457
Accrued income and other assets			5,285						4,842
Total assets			$	84,397					$	73,402
LIABILITIES AND SHAREHOLDERS’ EQUITY
Noninterest-bearing deposits			$	35,582					$	27,382
Money market and interest-bearing checking deposits			26,895						24,527
Savings deposits			2,500						2,184
Customer certificates of deposit			2,656						2,978
Other time deposits			—						133
Foreign office time deposits			87						91
Total interest-bearing deposits			32,138						29,913
Total deposits			67,720						57,295
Short-term borrowings			752						71
Accrued expenses and other liabilities			1,602						1,440
Medium- and long-term debt			6,521						7,269
Total liabilities			76,595						66,075
Fixed rate reset non-cumulative perpetual preferred stock, series A, no par value, $100,000 liquidation preference per share:
Authorized - 4,000 shares
Issued - 4,000 shares at 6/30/2020			395						—
Common stock - $5 par value:
Authorized - 325,000,000 shares
Issued - 228,164,824 shares			1,141						1,141
Capital surplus			2,173						2,174
Accumulated other comprehensive income (loss)			158						(235)
Retained earnings			9,404						9,538
Less cost of common stock in treasury - 89,124,560 shares at 6/30/2020 and 86,069,234 shares at 12/31/2019			(5,469)						(5,291)
Total shareholders’ equity			7,802						7,327
Total liabilities and shareholders’ equity			$	84,397					$	73,402

See notes to consolidated financial statements (unaudited).

1

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Table of Contents

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (unaudited)

Comerica Incorporated and Subsidiaries 

			Three Months Ended June 30,																		Six Months Ended June 30,
(in millions, except per share data)			2020						2019						2020						2019
INTEREST INCOME
Interest and fees on loans			$	434					$	635					$	951					$	1,256
Interest on investment securities			74						75						148						147
Interest on short-term investments			3						17						21						34
Total interest income			511						727						1,120						1,437
INTEREST EXPENSE
Interest on deposits			20						67						76						119
Interest on short-term borrowings			1						6						1						7
Interest on medium- and long-term debt			19						51						59						102
Total interest expense			40						124						136						228
Net interest income			471						603						984						1,209
Provision for credit losses			138						44						549						31
Net interest income after provision for credit losses			333						559						435						1,178
NONINTEREST INCOME
Card fees			68						65						127						128
Fiduciary income			52						52						106						101
Service charges on deposit accounts			42						51						91						102
Commercial lending fees			17						21						34						43
Foreign exchange income			9						11						20						22
Bank-owned life insurance			9						11						21						20
Letter of credit fees			9						10						18						19
Brokerage fees			5						7						12						14
Net securities gains (losses)			1						—						—						(8)
Other noninterest income			35						22						55						47
Total noninterest income			247						250						484						488
NONINTEREST EXPENSES
Salaries and benefits expense			249						245						491						510
Outside processing fee expense			62						65						119						128
Occupancy expense			37						37						74						74
Software expense			39						28						76						57
Equipment expense			12						12						24						24
Advertising expense			8						9						15						14
FDIC insurance expense			8						6						16						11
Other noninterest expenses			25						22						50						39
Total noninterest expenses			440						424						865						857
Income before income taxes			140						385						54						809
Provision for income taxes			27						87						6						172
NET INCOME			113						298						48						637
Less income allocated to participating securities			1						1						1						3
Net income attributable to common shares			$	112					$	297					$	47					$	634
Earnings per common share:
Basic			$	0.81					$	1.95					$	0.34					$	4.10
Diluted			0.80						1.94						0.34						4.06
Comprehensive income			97						429						441						864
Cash dividends declared on common stock			98						100						192						205
Cash dividends declared per common share			0.68						0.67						1.36						1.34

See notes to consolidated financial statements (unaudited).

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CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS’ EQUITY (unaudited)

Comerica Incorporated and Subsidiaries

															Accumulated
			Nonredeemable			Common Stock												Other									Total
			Preferred			Shares						Capital			Comprehensive			Retained			Treasury			Shareholders'
(in millions, except per share data)			Stock			Outstanding			Amount			Surplus			Income (Loss)			Earnings			Stock			Equity
BALANCE AT MARCH 31, 2019			$	—		155.4			$	1,141		$	2,159		$	(513)		$	8,979		$	(4,357)		$	7,409
Net income			—			—			—			—			—			298			—			298
Other comprehensive income, net of tax			—			—			—			—			131			—			—			131
Cash dividends declared on common stock ($0.67 per share)			—			—			—			—			—			(100)			—			(100)
Purchase of common stock			—			(5.7)			—			—			—			—			(425)			(425)
Net issuance of common stock under employee stock plans			—			0.1			—			1			—			(1)			2			2
Share-based compensation			—			—			—			8			—			—			—			8
BALANCE AT JUNE 30, 2019			$	—		149.8			$	1,141		$	2,168		$	(382)		$	9,176		$	(4,780)		$	7,323
BALANCE AT MARCH 31, 2020			$	—		139.0			$	1,141		$	2,168		$	174		$	9,389		$	(5,470)		$	7,402
Net income			—			—			—			—			—			113			—			113
Other comprehensive loss, net of tax			—			—			—			—			(16)			—			—			(16)
Cash dividends declared on common stock ($0.68 per share)			—			—			—			—			—			(98)			—			(98)
Purchase of common stock			—			—			—			—			—			—			1			1
Issuance of preferred stock			395			—			—			—			—			—			—			395
Net issuance of common stock under employee stock plans			—			—			—			1			—			—			—			1
Share-based compensation			—			—			—			4			—			—			—			4
BALANCE AT JUNE 30, 2020			$	395		139.0			$	1,141		$	2,173		$	158		$	9,404		$	(5,469)		$	7,802
BALANCE AT DECEMBER 31, 2018			$	—		160.1			$	1,141		$	2,148		$	(609)		$	8,781		$	(3,954)		$	7,507
Cumulative effect of change in accounting principle			—			—			—			—			—			(14)			—			(14)
Net income			—			—			—			—			—			637			—			637
Other comprehensive income, net of tax			—			—			—			—			227			—			—			227
Cash dividends declared on common stock ($1.34 per share)			—			—			—			—			—			(205)			—			(205)
Purchase of common stock			—			(10.9)			—			—			—			—			(859)			(859)
Net issuance of common stock under employee stock plans			—			0.6			—			(12)			—			(23)			33			(2)
Share-based compensation			—			—			—			32			—			—			—			32
BALANCE AT JUNE 30, 2019			$	—		149.8			$	1,141		$	2,168		$	(382)		$	9,176		$	(4,780)		$	7,323
BALANCE AT DECEMBER 31, 2019			$	—		142.1			$	1,141		$	2,174		$	(235)		$	9,538		$	(5,291)		$	7,327
Cumulative effect of change in accounting principle			—			—			—			—			—			13			—			13
Net income			—			—			—			—			—			48			—			48
Other comprehensive income, net of tax			—			—			—			—			393			—			—			393
Cash dividends declared on common stock ($1.36 per share)			—			—			—			—			—			(192)			—			(192)
Purchase of common stock			—			(3.4)			—			—			—			—			(194)			(194)
Issuance of preferred stock			395			—			—			—			—			—			—			395
Net issuance of common stock under employee stock plans			—			0.3			—			(13)			—			(3)			16			—
Share-based compensation			—			—			—			12			—			—			—			12
BALANCE AT JUNE 30, 2020			$	395		139.0			$	1,141		$	2,173		$	158		$	9,404		$	(5,469)		$	7,802

See notes to consolidated financial statements (unaudited).

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CONSOLIDATED STATEMENTS OF CASH FLOWS (unaudited)

Comerica Incorporated and Subsidiaries

			Six Months Ended June 30,
(in millions)			2020						2019
OPERATING ACTIVITIES
Net income			$	48					$	637
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for credit losses			549						31
Benefit for deferred income taxes			(95)						(4)
Depreciation and amortization			55						57
Net periodic defined benefit credit			(13)						(14)
Share-based compensation expense			12						32
Net amortization of securities			1						1
Net securities losses			—						8
Net change in:
Accrued income receivable			43						(12)
Accrued expenses payable			(64)						(86)
Other, net			208						(225)
Net cash provided by operating activities			744						425
INVESTING ACTIVITIES
Investment securities available-for-sale:
Maturities and redemptions			1,311						991
Sales			—						987
Purchases			(1,387)						(2,043)
Net change in loans			(3,229)						(1,685)
Proceeds from sales of foreclosed property			1						—
Net increase in premises and equipment			(29)						(29)
Federal Home Loan Bank stock:
Purchases			(51)						(49)
Redemptions			30						—
Proceeds from bank-owned life insurance settlements			10						7
Net cash used in investing activities			(3,344)						(1,821)
FINANCING ACTIVITIES
Net change in:
Deposits			10,327						(209)
Short-term borrowings			681						1,689
Medium- and long-term debt:
Maturities and redemptions			(925)						(350)
Issuances and advances			—						350
Preferred stock:
Issuance			395						—
Common stock:
Repurchases			(199)						(872)
Cash dividends paid			(191)						(203)
Issuances under employee stock plans			5						11
Net cash provided by financing activities			10,093						416
Net increase (decrease) in cash and cash equivalents			7,493						(980)
Cash and cash equivalents at beginning of period			5,818						4,561
Cash and cash equivalents at end of period			$	13,311					$	3,581
Interest paid			$	152					$	220
Income tax paid			77						161
Noncash investing and financing activities:
Loans transferred to other real estate			1						2

See notes to consolidated financial statements (unaudited).

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Notes to Consolidated Financial Statements (unaudited)

Comerica Incorporated and Subsidiaries

NOTE 1 - BASIS OF PRESENTATION AND ACCOUNTING POLICIES

Organization

The accompanying unaudited consolidated financial statements were prepared in accordance with United States (U.S.) generally accepted accounting principles (GAAP) for interim financial information and with the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, the statements do not include all of the information and footnotes required by GAAP for complete financial statements. In the opinion of management, all adjustments (consisting of normal recurring accruals) considered necessary for a fair presentation were included. The results of operations for the six months ended June 30, 2020 are not necessarily indicative of the results that may be expected for the year ending December 31, 2020. Certain items in prior periods were reclassified to conform to the current presentation. For further information, refer to the consolidated financial statements and footnotes thereto included in the Annual Report of Comerica Incorporated and Subsidiaries (the Corporation) on Form 10-K for the year ended December 31, 2019.

Allowance for Credit Losses

        The allowance for credit losses includes both the allowance for loan losses and the allowance for credit losses on lending-related commitments.

        The Corporation disaggregates the loan portfolio into segments for purposes of determining the allowance for credit losses. These segments are based on the level at which the Corporation develops, documents and applies a systematic methodology to determine the allowance for credit losses. The Corporation's portfolio segments are business loans and retail loans. Business loans include the commercial, real estate construction, commercial mortgage, lease financing and international loan portfolios. Retail loans consist of residential mortgage and consumer loans, including home equity loans.

        Effective January 1, 2020, the Corporation adopted the provisions of Accounting Standards Update (ASU) No. 2016-13, "Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments," commonly referred to as the current expected credit loss (CECL) model, for all financial assets, except those accounted for at fair value through net income, using the modified retrospective approach.

        Under Topic 326, current expected credit losses are estimated over the contractual life of the loan portfolio, considering all available relevant information, including historical and current conditions as well as reasonable and supportable forecasts of future events. The previous accounting principle estimated probable, estimable losses inherent in the portfolio.

        At adoption, the Corporation’s estimate of current expected credit losses in accordance with Topic 326 resulted in a $17 million day-one decrease in the overall allowance for credit losses, from $668 million at December 31, 2019 under the incurred loss model. The Corporation recognized a corresponding $13 million increase to retained earnings and a $4 million reduction to deferred tax assets. A similar adjustment at December 31, 2019 would have caused a 2-basis-point increase in the Common Equity Tier 1 (CET1) capital ratio. Business loans, comprising approximately 91 percent of the Corporation’s total loan portfolio at transition, consist of loans and lending arrangements with generally short contractual maturities. As a result, the allowance for credit losses for business loans decreased $42 million. The allowance for credit losses increased $25 million for retail loans, given their longer contractual maturities.

        Topic 326 also requires expected credit losses on available-for-sale (AFS) debt securities to be recorded as an allowance for credit losses. For certain types of debt securities, such as U.S. Treasuries and other securities with government guarantees, entities may expect zero credit losses. The zero-loss expectation applies to all the Corporation’s securities and no allowance for credit losses was recorded on its AFS securities portfolio at transition.

Allowance for Loan Losses

        The allowance for loan losses is estimated on a quarterly basis and represents management’s estimates of current expected credit losses in the Corporation’s loan portfolio. Pools of loans with similar risk characteristics are collectively evaluated while loans that no longer share risk characteristics with loan pools are evaluated individually.

        Collective loss estimates are determined by applying reserve factors, designed to estimate current expected credit losses, to amortized cost balances over the remaining contractual life of the collectively evaluated portfolio. Loans with similar risk characteristics are aggregated into homogeneous pools. Business loans are assigned to pools based primarily on business line and the Corporation’s internal risk rating system. For retail loans, pools are based on loan type, past due status and credit scores. Reserve factors are based on estimated probability of default for each pool, set to a default horizon based on contractual life, and loss given default. Historical estimates are calibrated to economic forecasts over the reasonable and supportable forecast period based on the projected performance of specific economic variables that statistically correlate with each of the probability of default and loss given default pools.

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Notes to Consolidated Financial Statements (unaudited)

Comerica Incorporated and Subsidiaries

        The calculation of current expected credit losses is inherently subjective, as it requires management to exercise judgment in determining appropriate factors used to determine the allowance. Some of the most significant factors in the quantitative allowance estimate are assigning internal risk ratings to loans, selecting the economic forecasts used to calibrate the reserve factors and determining the reasonable and supportable forecast period.

•Internal Risk Ratings: Loss factors are dependent on loan risk ratings for business loans. Risk ratings are assigned at origination, based on inherent credit risk, and may be updated based on new information that becomes available, periodic reviews of credit quality, a change in borrower performance or modifications to lending agreements.

•Economic Forecasts: Management selects economic variables it believes to be most relevant based on the composition of the loan portfolio and customer base, including forecasted levels of employment, gross domestic product, corporate bond and treasury spreads, industrial production levels, consumer and commercial real estate price indices as well as housing statistics. Different economic forecast scenarios ranging from more benign to more severe are evaluated each reporting period to forecast losses over the contractual life of the loan portfolio.

•Forecast Period: Economic forecasts are applied over the period management believes it can estimate reasonable and supportable forecasts. Forecast periods may be adjusted in response to changes in the economic environment. To estimate losses for contractual periods that extend beyond the forecast horizon, the Corporation reverts to an average historical loss experience. The Corporation typically forecasts economic variables over a two-year horizon, followed by an immediate reversion to an average historical loss experience that generally incorporates a full economic cycle. Management reviews this methodology on at least an annual basis.

        The allowance for loan losses also includes qualitative adjustments to bring the allowance to the level management believes is appropriate based on factors that have not otherwise been fully accounted for, including adjustments for foresight risk, input imprecision and model imprecision. Foresight risk reflects the inherent imprecision in forecasting economic variables, including determining the depth and duration of economic cycles and their impact to relevant economic variables. The Corporation may make qualitative adjustments based on its evaluation of different forecast scenarios and known recent events impacting relevant economic variables. Input imprecision factors address the risk that certain model inputs may not reflect all available information including (i) risk factors that have not been fully addressed in internal risk ratings, (ii) changes in lending policies and procedures, (iii) changes in the level and quality of experience held by lending management, (iv) imprecision in the risk rating system and (v) limitations in data available for certain loan portfolios. Model imprecision considers known model limitations and model updates not yet fully reflected in the quantitative estimate.

         The determination of the appropriate qualitative adjustment is based on management's analysis of current and expected economic conditions and their impact to the portfolio, as well as internal credit risk movements and a qualitative assessment of the lending environment, including underwriting standards. Management recognizes the sensitivity of various assumptions made in the quantitative modeling of expected losses and may adjust reserves depending upon the level of uncertainty that currently exists in one or more assumptions.

        Credit losses for loans that no longer share risk characteristics with the loan pools are estimated on an individual basis. Individual credit loss estimates are typically performed for nonaccrual loans and modified loans classified as troubled debt restructurings (TDRs) and are based on one of several methods, including the estimated fair value of the underlying collateral, observable market value of similar debt or the present value of expected cash flows. The Corporation considers certain loans to be collateral-dependent if the borrower is experiencing financial difficulty and management expects repayment for the loan to be substantially through the operation or sale of the collateral. For collateral-dependent loans, loss estimates are based on the fair value of collateral, less estimated cost to sell (if applicable). Collateral values supporting individually evaluated loans are assessed quarterly and appraisals are typically obtained at least annually.

        The total allowance for loan losses is sufficient to absorb expected credit losses over the contractual life of the portfolio. Unanticipated events impacting the economy, including political instability or global events affecting the U.S. economy, could cause changes to expectations for current conditions and economic forecasts that result in an unanticipated increase in the allowance. Significant increases in current portfolio exposures or changes in credit characteristics could also increase the amount of the allowance. Such events, or others of similar nature, may result in the need for additional provision for credit losses in order to maintain an allowance that complies with credit risk and accounting policies.

        Loans deemed uncollectible are charged off and deducted from the allowance. Recoveries on loans previously charged off are added to the allowance.

        Credit losses are not estimated for accrued interest receivable as interest that is deemed uncollectible is written off through interest income.

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Notes to Consolidated Financial Statements (unaudited)

Comerica Incorporated and Subsidiaries

Allowance for Credit Losses on Lending-Related Commitments

The allowance for credit losses on lending-related commitments estimates current expected credit losses on collective pools of letters of credit and unused commitments to extend credit based on reserve factors, determined in a manner similar to business loans, multiplied by a probability of draw estimate, based on historical experience and credit risk, applied to commitment amounts. The allowance for credit losses on lending-related commitments is included in accrued expenses and other liabilities on the Consolidated Balance Sheets, with the corresponding charge included in the provision for credit losses on the Consolidated Statements of Comprehensive Income.

Goodwill

        Effective January 1, 2020, the Corporation prospectively adopted the provisions of ASU No. 2017-04, “Intangibles - Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment,” (ASU 2017-04), eliminating the second step of goodwill impairment testing, under which the implied fair value of goodwill was determined as if the reporting unit were being acquired in a business combination. Under ASU 2017-04, the Corporation will compare the fair value of a reporting unit with its carrying amount and recognize an impairment charge for any amount by which the carrying amount exceeds the reporting unit’s fair value, to the extent that the loss recognized does not exceed the amount of goodwill allocated to that reporting unit. The adoption of ASU 2017-04 did not impact the Corporation’s current financial condition or results of operations.

        Goodwill, included in accrued income and other assets on the Consolidated Balance Sheets, is initially recorded as the excess of the purchase price over the fair value of net assets acquired in a business combination and is subsequently evaluated at least annually for impairment. Goodwill impairment testing is performed at the reporting unit level, equivalent to a business segment or one level below. The Corporation has three reporting units: the Commercial Bank, the Retail Bank and Wealth Management.

        The Corporation performs its annual evaluation of goodwill impairment in the third quarter of each year and may elect to perform a quantitative impairment analysis or first conduct a qualitative analysis to determine if a quantitative analysis is necessary. Additionally, the Corporation evaluates goodwill impairment on an interim basis if events or changes in circumstances between annual tests indicate additional testing may be warranted to determine if goodwill might be impaired. Factors considered in the assessment of the likelihood of impairment include macroeconomic conditions, industry and market considerations, stock performance of the Corporation and its peers, financial performance of the reporting units, and previous results of goodwill impairment tests, amongst other factors. Based on the results of the qualitative analysis, the Corporation determines whether a quantitative test is deemed necessary. The quantitative test compares the estimated fair value of identified reporting units with their carrying amount, including goodwill. If the estimated fair value of the reporting unit is less than the carrying value, an impairment charge would be recorded for the excess, not to exceed the amount of goodwill allocated to the reporting unit.

Software

        Effective January 1, 2020, the Corporation adopted the provisions of ASU No. 2018-15, “Intangibles - Goodwill and Other - Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract," using a prospective approach for implementation costs incurred subsequent to the adoption of the standard. Amortization expense from capitalized implementation costs of hosting arrangements that are service contracts and fees associated with the hosting elements of the arrangements, are included in software expense in the Consolidated Statements of Comprehensive Income, along with other software-related expenses. For the three- and six-month periods ended June 30, 2020, software expense included $8 million and $15 million of hosting fees that would have previously been included in outside processing fee expense.

        Capitalized software, stated at cost less accumulated amortization, includes purchased software, capitalizable application development costs associated with internally developed software and cloud computing arrangements, including capitalizable implementation costs associated with hosting arrangements that are service contracts. Amortization, computed on the straight-line method, is charged to software expense in the Consolidated Statements of Comprehensive Income over the estimated useful life of the software, generally 5 years, or the term of the hosting arrangement for implementation costs related to service contracts.

        Cloud computing arrangements include software as a service (SaaS), platform as a service (PaaS), infrastructure as a service (IaaS) and other similar hosting arrangements. The Corporation primarily utilizes SaaS and IaaS arrangements.

        Capitalized implementation costs of hosting arrangements that are service contracts were insignificant for the three- and six-month periods ended June 30, 2020.

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Notes to Consolidated Financial Statements (unaudited)

Comerica Incorporated and Subsidiaries

Reference Rate Reform

        In March 2020, the Financial Accounting Standards Board (FASB) issued ASU No. 2020-04, “Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting,” (ASU 2020-04), to provide temporary optional guidance to ease the potential accounting burden of reference rate reform. ASU 2020-04 is effective for eligible contract modifications from January 1, 2020 through December 31, 2022. Approximately 72 percent of the Corporation’s loans at June 30, 2020 were tied to the London Interbank Offered Rate (LIBOR). The Corporation uses interest rate swaps to convert variable-LIBOR rate loans to fixed rates for approximately 11 percent of the loan portfolio. Additional contracts with exposure to LIBOR include swaps converting fixed-rate long-term debt to variable LIBOR rates. The Corporation adopted the provisions of ASU 2020-04 for loan contract modifications as of January 1, 2020 and for all existing hedging relationships as of that date or entered into in the first quarter of 2020.

NOTE 2 – FAIR VALUE MEASUREMENTS

The Corporation utilizes fair value measurements to record fair value adjustments to certain assets and liabilities and to determine fair value disclosures. The determination of fair values of financial instruments often requires the use of estimates. In cases where quoted market values in an active market are not available, the Corporation uses present value techniques and other valuation methods to estimate the fair values of its financial instruments. These valuation methods require considerable judgment and the resulting estimates of fair value can be significantly affected by the assumptions made and methods used.

Investment securities available-for-sale, derivatives, deferred compensation plans and equity securities with readily determinable fair values (primarily money market mutual funds) are recorded at fair value on a recurring basis. Additionally, from time to time, the Corporation may be required to record other assets and liabilities at fair value on a nonrecurring basis, such as nonaccrual loans and loans classified as TDRs, other real estate (primarily foreclosed property), nonmarketable equity securities and certain other assets and liabilities. These nonrecurring fair value adjustments typically involve write-downs of individual assets or application of lower of cost or fair value accounting.

Refer to Note 1 to the consolidated financial statements in the Corporation's Annual Report on Form 10-K for the year ended December 31, 2019 for further information about the fair value hierarchy, descriptions of the valuation methodologies and key inputs used to measure financial assets and liabilities recorded at fair value, as well as a description of the methods and significant assumptions used to estimate fair value disclosures for financial instruments not recorded at fair value in their entirety on a recurring basis.

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Notes to Consolidated Financial Statements (unaudited)

Comerica Incorporated and Subsidiaries

Assets and Liabilities Recorded at Fair Value on a Recurring Basis

The following tables present the recorded amount of assets and liabilities measured at fair value on a recurring basis as of June 30, 2020 and December 31, 2019.

(in millions)			Total						Level 1						Level 2						Level 3
June 30, 2020
Deferred compensation plan assets			$	92					$	92					$	—					$	—
Equity securities			50						50						—						—
Investment securities available-for-sale:
U.S. Treasury and other U.S. government agency securities			2,852						2,852						—						—
Residential mortgage-backed securities (a)			9,907						—						9,907						—
Total investment securities available-for-sale			12,759						2,852						9,907						—
Derivative assets:
Interest rate contracts			649						—						605						44
Energy derivative contracts			271						—						271						—
Foreign exchange contracts			15						—						15						—
Total derivative assets			935						—						891						44
Total assets at fair value			$	13,836					$	2,994					$	10,798					$	44
Derivative liabilities:
Interest rate contracts			$	73					$	—					$	73					$	—
Energy derivative contracts			263						—						263						—
Foreign exchange contracts			15						—						15						—
Total derivative liabilities			351						—						351						—
Deferred compensation plan liabilities			92						92						—						—
Total liabilities at fair value			$	443					$	92					$	351					$	—
December 31, 2019
Deferred compensation plan assets			$	95					$	95					$	—					$	—
Equity securities			54						54						—						—
Investment securities available-for-sale:
U.S. Treasury and other U.S. government agency securities			2,792						2,792						—						—
Residential mortgage-backed securities (a)			9,606						—						9,606						—
Total investment securities available-for-sale			12,398						2,792						9,606						—
Derivative assets:
Interest rate contracts			211						—						189						22
Energy derivative contracts			96						—						96						—
Foreign exchange contracts			10						—						10						—
Total derivative assets			317						—						295						22
Total assets at fair value			$	12,864					$	2,941					$	9,901					$	22
Derivative liabilities:
Interest rate contracts			$	39					$	—					$	39					$	—
Energy derivative contracts			92						—						92						—
Foreign exchange contracts			10						—						10						—
Total derivative liabilities			141						—						141						—
Deferred compensation plan liabilities			95						95						—						—
Total liabilities at fair value			$	236					$	95					$	141					$	—

(a)Issued and/or guaranteed by U.S. government agencies or U.S. government-sponsored enterprises.

        There were no transfers of assets or liabilities recorded at fair value on a recurring basis into or out of Level 3 fair value measurements during each of the three- and six-month periods ended June 30, 2020 and 2019.

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Notes to Consolidated Financial Statements (unaudited)

Comerica Incorporated and Subsidiaries

The following table summarizes the changes in Level 3 assets and liabilities measured at fair value on a recurring basis for the three- and six-month periods ended June 30, 2020 and 2019.

												Net Realized/Unrealized Gains (Losses) (Pretax) Recorded in Earnings (a)
			Balance  at Beginning of Period																																																									Balance at End of Period
																																																			Payments, Sales and Redemptions
(in millions)															Realized									Unrealized
Three Months Ended June 30, 2020
Derivative assets:
Interest rate contracts			$	43								$	—					$	1																	$	—											$	44
Three Months Ended June 30, 2019
Derivative assets:
Interest rate contracts			$	14								$	—					$	7																	$	—											$	21
Six Months Ended June 30, 2020
Derivative assets:
Interest rate contracts			$	22								$	—					$	22																	$	—											$	44
Six Months Ended June 30, 2019
Derivative assets:
Interest rate contracts			$	9								$	—					$	12																	$	—											$	21

(a)Realized and unrealized gains and losses due to changes in fair value are recorded in other noninterest income on the Consolidated Statements of Comprehensive Income.

Assets and Liabilities at Fair Value on a Nonrecurring Basis

The Corporation may be required to record certain assets and liabilities at fair value on a nonrecurring basis. These include assets that are recorded at the lower of cost or fair value, and were recognized at fair value since it was less than cost at the end of the period.

The following table presents assets recorded at fair value on a nonrecurring basis at June 30, 2020 and December 31, 2019. No liabilities were recorded at fair value on a nonrecurring basis at June 30, 2020 and December 31, 2019.

(in millions)															Level 3
June 30, 2020
Loans:
Commercial															$	146
Total assets at fair value															$	146
December 31, 2019
Loans:
Commercial															$	70
Total assets at fair value															$	70

Level 3 assets recorded at fair value on a nonrecurring basis at June 30, 2020 and December 31, 2019 included both nonaccrual loans and TDRs for which a specific allowance was established based on the fair value of collateral. The unobservable inputs were the additional adjustments applied by management to the appraised values to reflect such factors as non-current appraisals and revisions to estimated time to sell. These adjustments are determined based on qualitative judgments made by management on a case-by-case basis and are not quantifiable inputs, although they are used in the determination of fair value.

Estimated Fair Values of Financial Instruments Not Recorded at Fair Value on a Recurring Basis

The Corporation typically holds the majority of its financial instruments until maturity and thus does not expect to realize many of the estimated fair value amounts disclosed. The disclosures also do not include estimated fair value amounts for items that are not defined as financial instruments, but which have significant value. These include such items as core deposit intangibles, the future earnings potential of significant customer relationships and the value of trust operations and other fee generating businesses. The Corporation believes the imprecision of an estimate could be significant.

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Notes to Consolidated Financial Statements (unaudited)

Comerica Incorporated and Subsidiaries

The carrying amount and estimated fair value of financial instruments not recorded at fair value in their entirety on a recurring basis on the Corporation’s Consolidated Balance Sheets are as follows:

			Carrying Amount						Estimated Fair Value
(in millions)												Total						Level 1						Level 2						Level 3
June 30, 2020
Assets
Cash and due from banks			$	1,048					$	1,048					$	1,048					$	—					$	—
Interest-bearing deposits with banks			12,263						12,263						12,263						—						—
Loans held-for-sale			11						11						—						11						—
Total loans, net of allowance for loan losses (a)			52,439						52,273						—						—						52,273
Customers’ liability on acceptances outstanding			2						2						2						—						—
Restricted equity investments			269						269						269						—						—
Nonmarketable equity securities (b)			5						10
Liabilities
Demand deposits (noninterest-bearing)			35,582						35,582						—						35,582						—
Interest-bearing deposits			29,482						29,482						—						29,482						—
Customer certificates of deposit			2,656						2,662						—						2,662						—
Total deposits			67,720						67,726						—						67,726						—
Short-term borrowings			752						752						752						—						—
Acceptances outstanding			2						2						2						—						—
Medium- and long-term debt			6,521						6,465						—						6,465						—
Credit-related financial instruments			(81)						(81)						—						—						(81)
December 31, 2019
Assets
Cash and due from banks			$	973					$	973					$	973					$	—					$	—
Interest-bearing deposits with banks			4,845						4,845						4,845						—						—
Loans held-for-sale			6						6						—						6						—
Total loans, net of allowance for loan losses (a)			49,732						49,975						—						—						49,975
Customers’ liability on acceptances outstanding			2						2						2						—						—
Restricted equity investments			248						248						248						—						—
Nonmarketable equity securities (b)			5						10
Liabilities
Demand deposits (noninterest-bearing)			27,382						27,382						—						27,382						—
Interest-bearing deposits			26,802						26,802						—						26,802						—
Certificates of deposit			2,978						2,968						—						2,968						—
Other time deposits			133						133						—						133						—
Total deposits			57,295						57,285						—						57,285						—
Short-term borrowings			71						71						71						—						—
Acceptances outstanding			2						2						2						—						—
Medium- and long-term debt			7,269						7,316						—						7,316						—
Credit-related financial instruments			(57)						(57)						—						—						(57)

(a)Included $146 million and $70 million of loans recorded at fair value on a nonrecurring basis at June 30, 2020 and December 31, 2019, respectively.

(b)Certain investments that are measured at fair value using the net asset value have not been classified in the fair value hierarchy. The fair value amounts presented in the table are intended to permit reconciliation of the fair value hierarchy to the amounts presented in the Consolidated Balance Sheets.

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Notes to Consolidated Financial Statements (unaudited)

Comerica Incorporated and Subsidiaries

NOTE 3 - INVESTMENT SECURITIES

A summary of the Corporation’s investment securities follows:

(in millions)			Amortized Cost						Gross Unrealized Gains						Gross Unrealized Losses						Fair Value
June 30, 2020
Investment securities available-for-sale:
U.S. Treasury and other U.S. government agency securities			$	2,747					$	105					$	—					$	2,852
Residential mortgage-backed securities (a)			9,641						266						—						9,907
Total investment securities available-for-sale			$	12,388					$	371					$	—					$	12,759
December 31, 2019
Investment securities available-for-sale:
U.S. Treasury and other U.S. government agency securities			$	2,745					$	47					$	—					$	2,792
Residential mortgage-backed securities (a)			9,568						66						28						9,606
Total investment securities available-for-sale			$	12,313					$	113					$	28					$	12,398

(a)Issued and/or guaranteed by U.S. government agencies or U.S. government-sponsored enterprises.

A summary of the Corporation’s investment securities in an unrealized loss position as of June 30, 2020 and December 31, 2019 follows:

			Temporarily Impaired
			Less than 12 Months																								12 Months or more																								Total
(in millions)			Fair Value						Unrealized Losses												Fair Value						Unrealized Losses												Fair Value						Unrealized Losses
June 30, 2020
Residential mortgage-backed securities (a)			$	1					$	—								$	—					$	—								$	1					$	—
Total temporarily impaired securities			$	1					$	—								$	—					$	—								$	1					$	—
December 31, 2019
Residential mortgage-backed securities (a)			$	1,494					$	7								$	1,906					$	21								$	3,400					$	28
Total temporarily impaired securities			$	1,494					$	7								$	1,906					$	21								$	3,400					$	28

(a)Issued and/or guaranteed by U.S. government agencies or U.S. government-sponsored enterprises.

Unrealized losses resulted from changes in market interest rates and liquidity. The Corporation’s portfolio is comprised of securities issued or guaranteed by the U.S. government or government-sponsored enterprises. As such, it is expected that the securities would not be settled at a price less than the amortized cost of the investments. Further, the Corporation does not intend to sell the investments, and it is not more likely than not that it will be required to sell the investments before recovery of amortized costs.

Interest receivable on investment securities totaled $19 million at June 30, 2020 and $20 million at December 31, 2019 and was included in accrued income and other assets on the Consolidated Balance Sheets.

Sales, calls and write-downs of investment securities available-for-sale resulted in the following gains and losses recorded in net securities gains (losses) on the Consolidated Statements of Comprehensive Income, computed based on the adjusted cost of the specific security.

			Three Months Ended June 30,																		Six Months Ended June 30,
(in millions)			2020						2019						2020						2019
Securities gains			$	1					$	—					$	1					$	—
Securities losses			—						—						(1)						(8)
Net securities gains (losses)			$	1					$	—					$	—					$	(8)

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Notes to Consolidated Financial Statements (unaudited)

Comerica Incorporated and Subsidiaries

The following table summarizes the amortized cost and fair values of debt securities by contractual maturity. Securities with multiple maturity dates are classified in the period of final maturity. Expected maturities will differ from contractual maturities because borrowers may have the right to call or prepay obligations with or without call or prepayment penalties.

(in millions)
June 30, 2020			Amortized Cost						Fair Value
Contractual maturity
Within one year			$	780					$	796
After one year through five years			2,115						2,212
After five years through ten years			872						898
After ten years			8,621						8,853
Total investment securities			$	12,388					$	12,759

Included in the contractual maturity distribution in the table above were residential mortgage-backed securities with a total amortized cost of $9.6 billion and a fair value of $9.9 billion. The actual cash flows of mortgage-backed securities may differ as borrowers of the underlying loans may exercise prepayment options.

At June 30, 2020, investment securities with a carrying value of $5.7 billion were pledged where permitted or required by law, including $5.2 billion pledged to the Federal Home Loan Bank (FHLB) as collateral for potential future borrowings of approximately $5.0 billion and $506 million to secure $432 million of liabilities, primarily public and other deposits of state and local government agencies as well as derivative instruments. For information on FHLB borrowings, refer to Note 7.

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Notes to Consolidated Financial Statements (unaudited)

Comerica Incorporated and Subsidiaries

NOTE 4 – CREDIT QUALITY AND ALLOWANCE FOR CREDIT LOSSES

The following table presents an aging analysis of the amortized cost basis of loans.

			Loans Past Due and Still Accruing
(in millions)			30-59 Days						60-89  Days						90 Days or More						Total						Nonaccrual Loans						Current Loans (a)						Total  Loans
June 30, 2020
Business loans:
Commercial			$	48					$	53					$	24					$	125					$	200					$	33,501					$	33,826
Real estate construction:
Commercial Real Estate business line (b)			16						—						—						16						$	—					3,531						3,547
Other business lines (c)			—						3						—						3						—						402						405
Total real estate construction			16						3						—						19						—						3,933						3,952
Commercial mortgage:
Commercial Real Estate business line (b)			1						9						—						10						$	3					2,279						2,292
Other business lines (c)			25						2						6						33						18						7,582						7,633
Total commercial mortgage			26						11						6						43						21						9,861						9,925
Lease financing			—						—						—						—						1						588						589
International			—						—						5						5						—						1,099						1,104
Total business loans			90						67						35						192						222						48,982						49,396
Retail loans:
Residential mortgage			27						9						—						36						24						1,826						1,886
Consumer:
Home equity			12						1						—						13						21						1,635						1,669
Other consumer			1						—						6						7						—						488						495
Total consumer			13						1						6						20						21						2,123						2,164
Total retail loans			40						10						6						56						45						3,949						4,050
Total loans			$	130					$	77					$	41					$	248					$	267					$	52,931					$	53,446
December 31, 2019
Business loans:
Commercial			$	27					$	7					$	17					$	51					$	148					$	31,274					$	31,473
Real estate construction:
Commercial Real Estate business line (b)			6						—						—						6						—						3,038						3,044
Other business lines (c)			—						7						—						7						—						404						411
Total real estate construction			6						7						—						13						—						3,442						3,455
Commercial mortgage:
Commercial Real Estate business line (b)			9						—						—						9						2						2,165						2,176
Other business lines (c)			16						18						9						43						12						7,328						7,383
Total commercial mortgage			25						18						9						52						14						9,493						9,559
Lease financing			1						—						—						1						—						587						588
International			—						5						—						5						—						1,004						1,009
Total business loans			59						37						26						122						162						45,800						46,084
Retail loans:
Residential mortgage			15						2						—						17						20						1,808						1,845
Consumer:
Home equity			4						5						—						9						17						1,685						1,711
Other consumer			2						3						—						5						—						724						729
Total consumer			6						8						—						14						17						2,409						2,440
Total retail loans			21						10						—						31						37						4,217						4,285
Total loans			$	80					$	47					$	26					$	153					$	199					$	50,017					$	50,369

(a)Includes $4.5 billion of loans with deferred payments not considered past due in accordance with the Coronavirus Aid, Relief, and Economic Security Act (CARES Act) at June 30, 2020.

(b)Primarily loans to real estate developers.

(c)Primarily loans secured by owner-occupied real estate.

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Notes to Consolidated Financial Statements (unaudited)

Comerica Incorporated and Subsidiaries

The following table presents loans by credit quality indicator (CQI) and vintage year. CQI is based on internal risk ratings assigned to each business loan at the time of approval and subjected to subsequent reviews, generally at least annually, and to pools of retail loans with similar risk characteristics. Vintage year is the year of origination or major modification.

			June 30, 2020																																																																																																						December 31, 2019
			Vintage Year
(in millions)			2020						2019						2018						2017						2016						Prior						Revolvers						Revolvers Converted to Term						Total						Total
Business loans:
Commercial:
Pass (a)			$	5,029		(b)			$	2,673					$	1,876					$	1,259					$	572					$	966					$	18,708					$	16					$	31,099					$	29,785
Criticized (c)			30						305						239						147						104						205						1,695						2						2,727						1,688
Total commercial			5,059						2,978						2,115						1,406						676						1,171						20,403						18						33,826						31,473
Real estate construction
Pass (a)			127						878						1,293						795						458						218						152						—						3,921						3,424
Criticized (c)			—						2						4						24						—						1						—						—						31						31
Total real estate construction			127						880						1,297						819						458						219						152						—						3,952						3,455
Commercial mortgage
Pass (a)			1,058						1,713						1,220						1,254						915						2,790						499						—						9,449						9,262
Criticized (c)			31						96						32						47						47						215						8						—						476						297
Total commercial mortgage			1,089						1,809						1,252						1,301						962						3,005						507						—						9,925						9,559
Lease financing
Pass (a)			63						131						84						56						17						213						—						—						564						579
Criticized (c)			1						18						3						2						1						—						—						—						25						9
Total lease financing			64						149						87						58						18						213						—						—						589						588
International
Pass (a)			272						185						129						13						3						75						374						—						1,051						972
Criticized (c)			5						—						—						10						8						2						28						—						53						37
Total international			277						185						129						23						11						77						402						—						1,104						1,009
Total business loans			6,616						6,001						4,880						3,607						2,125						4,685						21,464						18						49,396						46,084
Retail loans:
Residential mortgage
Pass (a)			355						251						149						305						255						538						—						—						1,853						1,823
Criticized (c)			—						—						5						4						3						21						—						—						33						22
Total residential mortgage			355						251						154						309						258						559						—						—						1,886						1,845
Consumer:
Home equity
Pass (a)			—						—						—						—						—						19						1,544						82						1,645						1,682
Criticized (c)			—						—						—						—						—						1						17						6						24						29
Total home equity			—						—						—						—						—						20						1,561						88						1,669						1,711
Other consumer
Pass (a)			13						79						19						4						6						58						306						—						485						722
Criticized (c)			—						1						3						—						—						—						6						—						10						7
Total other consumer			13						80						22						4						6						58						312						—						495						729
Total consumer			13						80						22						4						6						78						1,873						88						2,164						2,440
Total retail loans			368						331						176						313						264						637						1,873						88						4,050						4,285
Total loans			$	6,984					$	6,332					$	5,056					$	3,920					$	2,389					$	5,322					$	23,337					$	106					$	53,446					$	50,369

(a)Includes all loans not included in the categories of special mention, substandard or nonaccrual.

(b)Includes $3.8 billion of Small Business Administration Paycheck Protection Program (PPP) loans at June 30, 2020.

(c)Includes loans with an internal rating of special mention, substandard loans for which the accrual of interest has not been discontinued and nonaccrual loans. Special mention loans have potential credit weaknesses that deserve management’s close attention, such as loans to borrowers who may be experiencing financial difficulties that may result in deterioration of repayment prospects from the borrower at some future date. Accruing substandard loans have a well-defined weakness, or weaknesses, such as loans to borrowers who may be experiencing losses from operations or inadequate liquidity of a degree and duration that jeopardizes the orderly repayment of the loan. Substandard loans are also distinguished by the distinct possibility of loss in the future if these weaknesses are not corrected. Nonaccrual loans are loans for which the accrual of interest has been discontinued. For further information regarding nonaccrual loans, refer to the Nonperforming Assets subheading in Note 1 - Basis of Presentation and Accounting Policies - on page F-51 in the Corporation's 2019 Annual Report. These categories are generally consistent with the "special mention" and "substandard" categories as defined by regulatory authorities. A minority of nonaccrual loans are consistent with the "doubtful" category.

Loan interest receivable totaled $132 million and $172 million at June 30, 2020 and December 31, 2019, respectively, and was included in accrued income and other assets on the Consolidated Balance Sheets.

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Notes to Consolidated Financial Statements (unaudited)

Comerica Incorporated and Subsidiaries

Allowance for Credit Losses

The following table details the changes in the allowance for credit losses.

			2020																														2019
(in millions)			Business Loans						Retail Loans						Total						Business Loans						Retail Loans						Total
Three Months Ended June 30
Balance at beginning of period:
Allowance for loan losses			$	861					$	55					$	916					$	608					$	39					$	647
Allowance for credit losses on lending-related commitments			52						10						62						27						3						30
Allowance for credit losses			913						65						978						635						42						677
Loan charge-offs			(56)						(1)						(57)						(43)						(1)						(44)
Recoveries on loans previously charged-off			6						1						7						10						1						11
Net loan charge-offs			(50)						—						(50)						(33)						—						(33)
Provision for credit losses:
Provision for loan losses			132						9						141						43						—						43
Provision for credit losses on lending-related commitments			(2)						(1)						(3)						1						—						1
Provision for credit losses			130						8						138						44						—						44
Balance at end of period:
Allowance for loan losses			943						64						1,007						618						39						657
Allowance for credit losses on lending-related commitments			50						9						59						28						3						31
Allowance for credit losses			$	993					$	73					$	1,066					$	646					$	42					$	688
Six Months Ended June 30
Balance at beginning of period
Allowance for loan losses			$	601					$	36					$	637					$	627					$	44					$	671
Allowance for credit losses on lending-related commitments			28						3						31						26						4						30
Allowance for credit losses			629						39						668						653						48						701
Cumulative effect of change in accounting principle			(42)						25						(17)						—						—						—
Loan charge-offs			(143)						(3)						(146)						(62)						(2)						(64)
Recoveries on loans previously charged-off			11						1						12						18						2						20
Net loan charge-offs			(132)						(2)						(134)						(44)						—						(44)
Provision for credit losses:
Provision for loan losses			516						5						521						35						(5)						30
Provision for credit losses on lending-related commitments			22						6						28						2						(1)						1
Provision for credit losses			538						11						549						37						(6)						31
Balance at end of period:
Allowance for loan losses			943						64						1,007						618						39						657
Allowance for credit losses on lending-related commitments			50						9						59						28						3						31
Allowance for credit losses			$	993					$	73					$	1,066					$	646					$	42					$	688
Allowance for loan losses as a percentage of total loans			1.91		%				1.59		%				1.88		%				1.30		%				0.89		%				1.27		%
Allowance for loan losses as a percentage of total loans excluding PPP loans			2.07		%				n/a						2.03		%				n/a						n/a						n/a
Allowance for credit losses as a percentage of total loans			2.01		%				1.82		%				1.99		%				1.36		%				0.96		%				1.33		%
Allowance for credit losses as a percentage of total loans excluding PPP loans			2.18		%				n/a						2.15		%				n/a						n/a						n/a

n/a - not applicable

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Notes to Consolidated Financial Statements (unaudited)

Comerica Incorporated and Subsidiaries

Nonaccrual Loans

The following table presents additional information regarding nonaccrual loans. No interest income was recognized on nonaccrual loans for the three- and six-month periods ended June 30, 2020 and 2019, respectively.

(in millions)			Nonaccrual Loans with No Related Allowance						Nonaccrual Loans with Related Allowance						Total Nonaccrual Loans
June 30, 2020
Business loans:
Commercial			$	32					$	168					$	200
Commercial mortgage:
Commercial Real Estate business line (a)			2						1						3
Other business lines (b)			6						12						18
Total commercial mortgage			8						13						21
Lease financing			—						1						1
Total business loans			40						182						222
Retail loans:
Residential mortgage			24						—						24
Consumer:
Home equity			21						—						21
Total retail loans			45						—						45
Total nonaccrual loans			$	85					$	182					$	267
December 31, 2019
Business loans:
Commercial			$	29					$	119					$	148
Commercial mortgage:
Commercial Real Estate business line (a)			2						—						2
Other business lines (b)			1						11						12
Total commercial mortgage			3						11						14
Total business loans			32						130						162
Retail loans:
Residential mortgage			20						—						20
Consumer:
Home equity			17						—						17
Total retail loans			37						—						37
Total nonaccrual loans			$	69					$	130					$	199

(a)Primarily loans to real estate developers.

(b)Primarily loans secured by owner-occupied real estate.

Foreclosed Properties

Foreclosed properties totaled $11 million at both June 30, 2020 and December 31, 2019. There were no retail loans secured by residential real estate properties in process of foreclosure included in nonaccrual loans at June 30, 2020 and December 31, 2019.

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Notes to Consolidated Financial Statements (unaudited)

Comerica Incorporated and Subsidiaries

Troubled Debt Restructurings

The following table details the amortized cost basis at June 30, 2020 and 2019 of loans considered to be TDRs that were restructured during the three- and six-month periods ended June 30, 2020 and 2019, by type of modification. In cases of loans with more than one type of modification, the loans were categorized based on the most significant modification.

			2020																		2019
			Type of Modification															Type of Modification
(in millions)			Principal Deferrals (a)			Interest Rate Reductions			Total Modifications						Principal Deferrals (a)			Interest Rate Reductions			Total Modifications
Three Months Ended June 30,
Home equity (b)			$	—		$	—		$	—					$	—		$	1		$	1
Total loans			$	—		$	—		$	—					$	—		$	1		$	1
Six Months Ended June 30,
Business loans:
Commercial			$	16		$	—		$	16					$	11		$	—		$	11
Commercial mortgage:
Other business lines (c)			1			—			$	1					1			—			1
Total business loans			17			—			17						12			—			12
Retail loans:
Consumer:
Home equity (b)			—			—			—						—			1			1
Total loans			$	17		$	—		$	17					$	12		$	1		$	13

(a)Primarily represents loan balances where terms were extended by more than an insignificant time period, typically more than 180 days, at or above contractual interest rates. Also includes commercial loans restructured in bankruptcy.

(b)Includes bankruptcy loans for which the court has discharged the borrower's obligation and the borrower has not reaffirmed the debt.

(c)Primarily loans secured by owner-occupied real estate.

The Corporation charges interest on principal balances outstanding during deferral periods. Additionally, none of the modifications involved forgiveness of principal. At June 30, 2020 and December 31, 2019, commitments to lend additional funds to borrowers whose terms have been modified in TDRs totaled $2 million and $3 million, respectively. On an ongoing basis, the Corporation monitors the performance of modified loans to their restructured terms. The allowance for loan losses continues to be reassessed on the basis of an individual evaluation of the loan.

For principal deferrals, incremental deterioration in the credit quality of the loan, represented by a downgrade in the risk rating of the loan, for example, due to missed interest payments or a reduction of collateral value, is considered a subsequent default. For interest rate reductions, a subsequent payment default is defined in terms of delinquency, when a principal or interest payment is 90 days past due. Of the TDRs modified during the twelve-month periods ended June 30, 2020 and 2019, principal deferrals totaled $6 million and $15 million in the three- and six-month periods ended June 30, 2020, respectively compared to none in the comparable periods in 2019. There were no subsequent defaults of interest rate reductions during either of the three- and six-month periods ended June 30, 2020 and 2019.

NOTE 5 - DERIVATIVE AND CREDIT-RELATED FINANCIAL INSTRUMENTS

In the normal course of business, the Corporation enters into various transactions involving derivative and credit-related financial instruments to manage exposure to fluctuations in interest rate, foreign currency and other market risks and to meet the financing needs of customers (customer-initiated derivatives). These financial instruments involve, to varying degrees, elements of market and credit risk. Market and credit risk are included in the determination of fair value.

Market risk is the potential loss that may result from movements in interest rates, foreign currency exchange rates or energy commodity prices that cause an unfavorable change in the value of a financial instrument. The Corporation manages this risk by establishing monetary exposure limits and monitoring compliance with those limits. Market risk inherent in interest rate and energy contracts entered into on behalf of customers is mitigated by taking offsetting positions, except in those circumstances when the amount, tenor and/or contract rate level results in negligible economic risk, whereby the cost of purchasing an offsetting contract is not economically justifiable. The Corporation mitigates most of the inherent market risk in foreign exchange contracts entered into on behalf of customers by taking offsetting positions and manages the remainder through individual foreign currency position limits and aggregate value-at-risk limits. These limits are established annually and positions are monitored quarterly. Market risk inherent in derivative instruments held or issued for risk management purposes is typically offset by changes in the fair value of the assets or liabilities being hedged.

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Notes to Consolidated Financial Statements (unaudited)

Comerica Incorporated and Subsidiaries

Credit risk is the possible loss that may occur in the event of nonperformance by the counterparty to a financial instrument. The Corporation attempts to minimize credit risk arising from customer-initiated derivatives by evaluating the creditworthiness of each customer, adhering to the same credit approval process used for traditional lending activities and obtaining collateral as deemed necessary. Derivatives with dealer counterparties are either cleared through a clearinghouse or settled directly with a single counterparty. For derivatives settled directly with dealer counterparties, the Corporation utilizes counterparty risk limits and monitoring procedures as well as master netting arrangements and bilateral collateral agreements to facilitate the management of credit risk. Master netting arrangements effectively reduce credit risk by permitting settlement of positive and negative positions and offset cash collateral held with the same counterparty on a net basis. Bilateral collateral agreements require daily exchange of cash or highly rated securities issued by the U.S. Treasury or other U.S. government entities to collateralize amounts due to either party. At June 30, 2020, counterparties with bilateral collateral agreements deposited $216 million of cash with the Corporation to secure the fair value of contracts in an unrealized gain position, and the Corporation had pledged $56 million of marketable investment securities and posted $30 million of cash as collateral for contracts in an unrealized loss position. For those counterparties not covered under bilateral collateral agreements, collateral is obtained, if deemed necessary, based on the results of management’s credit evaluation of the counterparty. Collateral varies, but may include cash, investment securities, accounts receivable, equipment or real estate. Included in the fair value of derivative instruments are credit valuation adjustments reflecting counterparty credit risk. These adjustments are determined by applying a credit spread for the counterparty or the Corporation, as appropriate, to the total expected exposure of the derivative. There were no derivative instruments with credit-risk-related contingent features that were in a liability position at June 30, 2020.

Derivative Instruments

Derivative instruments utilized by the Corporation are negotiated over-the-counter and primarily include swaps, caps and floors, forward contracts and options, each of which may relate to interest rates, energy commodity prices or foreign currency exchange rates. Swaps are agreements in which two parties periodically exchange cash payments based on specified indices applied to a specified notional amount until a stated maturity. Caps and floors are agreements which entitle the buyer to receive cash payments based on the difference between a specified reference rate or price and an agreed strike rate or price, applied to a specified notional amount until a stated maturity. Forward contracts are over-the-counter agreements to buy or sell an asset at a specified future date and price. Options are similar to forward contracts except the purchaser has the right, but not the obligation, to buy or sell the asset during a specified period or at a specified future date.

Over-the-counter contracts are tailored to meet the needs of the counterparties involved and, therefore, contain a greater degree of credit risk and liquidity risk than exchange-traded contracts, which have standardized terms and readily available price information. The Corporation reduces exposure to market and liquidity risks from over-the-counter derivative instruments entered into for risk management purposes, and transactions entered into to mitigate the market risk associated with customer-initiated transactions, by taking offsetting positions with investment grade domestic and foreign financial institutions and subjecting counterparties to credit approvals, limits and collateral monitoring procedures similar to those used in making other extensions of credit. In addition, certain derivative contracts executed bilaterally with a dealer counterparty in the over-the-counter market are cleared through a clearinghouse, whereby the clearinghouse becomes the counterparty to the transaction.

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Notes to Consolidated Financial Statements (unaudited)

Comerica Incorporated and Subsidiaries

The following table presents the composition of the Corporation’s derivative instruments held or issued for risk management purposes or in connection with customer-initiated and other activities at June 30, 2020 and December 31, 2019. The table excludes commitments and warrants accounted for as derivatives.

			June 30, 2020																														December 31, 2019
									Fair Value																								Fair Value
(in millions)			Notional/ Contract Amount (a)						Gross Derivative Assets						Gross Derivative Liabilities						Notional/ Contract Amount (a)						Gross Derivative Assets						Gross Derivative Liabilities
Risk management purposes
Derivatives designated as hedging instruments
Interest rate contracts:
Swaps - fair value - receive fixed/pay floating			$	2,650					$	—					$	—					$	3,325					$	—					$	—
Swaps - cash flow - receive fixed/pay floating			5,550						—						—						4,550						—						—
Derivatives used as economic hedges
Foreign exchange contracts:
Spot, forwards and swaps			330						1						2						330						—						2
Total risk management purposes			8,530						1						2						8,205						—						2
Customer-initiated and other activities
Interest rate contracts:
Caps and floors written			601						—						1						671						—						—
Caps and floors purchased			601						1						—						671						—						—
Swaps			20,039						648						72						16,485						211						39
Total interest rate contracts			21,241						649						73						17,827						211						39
Energy contracts:
Caps and floors written			439						—						46						477						—						23
Caps and floors purchased			439						46						—						477						23						—
Swaps			2,137						225						217						2,135						73						69
Total energy contracts			3,015						271						263						3,089						96						92
Foreign exchange contracts:
Spot, forwards, options and swaps			968						14						13						1,013						10						8
Total customer-initiated and other activities			25,224						934						349						21,929						317						139
Total gross derivatives			$	33,754					$	935					$	351					$	30,134					$	317					$	141
Amounts offset in the Consolidated Balance Sheets:
Netting adjustment - Offsetting derivative assets/liabilities									(54)						(54)												(63)						(63)
Netting adjustment - Cash collateral received/posted									(214)						(28)												(11)						(12)
Net derivatives included in the Consolidated Balance Sheets (b)									667						269												243						66
Amounts not offset in the Consolidated Balance Sheets:
Marketable securities pledged under bilateral collateral agreements									—						(53)												—						(21)
Net derivatives after deducting amounts not offset in the Consolidated Balance Sheets									$	667					$	216											$	243					$	45

(a)Notional or contractual amounts, which represent the extent of involvement in the derivatives market, are used to determine the contractual cash flows required in accordance with the terms of the agreement. These amounts are typically not exchanged, significantly exceed amounts subject to credit or market risk and are not reflected in the Consolidated Balance Sheets.

(b)Net derivative assets are included in accrued income and other assets and net derivative liabilities are included in accrued expenses and other liabilities on the Consolidated Balance Sheets. Included in the fair value of net derivative assets and net derivative liabilities are credit valuation adjustments reflecting counterparty credit risk and credit risk of the Corporation. The fair value of net derivative assets included credit valuation adjustments for counterparty credit risk of $25 million and $9 million at June 30, 2020 and December 31, 2019, respectively.

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Notes to Consolidated Financial Statements (unaudited)

Comerica Incorporated and Subsidiaries

Risk Management

The Corporation's derivative instruments used for managing interest rate risk currently comprise swaps converting fixed-rate long-term debt to variable rates and variable-rate loans to fixed rates.

The following table details the effects of fair value hedging on the Consolidated Statements of Comprehensive Income.

			Interest on Medium- and Long-Term Debt
			Three Months Ended June 30,																		Six Months Ended June 30,
(in millions)			2020						2019						2020						2019
Total interest on medium- and long-term debt (a)			$	19					$	51					$	59					$	102
Fair value hedging relationships:
Interest rate contracts:
Hedged items			28						26						58						52
Derivatives designated as hedging instruments			(12)						—						(18)						1

(a) Includes the effects of hedging.

        For information on accumulated net gains on cash flow hedges, refer to Note 8.

        The following table summarizes the expected weighted average remaining maturity of the notional amount of risk management interest rate swaps, the carrying amount of the related hedged items and the weighted average interest rates associated with amounts expected to be received or paid on interest rate swap agreements as of June 30, 2020 and December 31, 2019.

Cash flow swaps - receive fixed/pay floating rate on variable-rate loans:

(dollar amounts in millions)			June 30, 2020						December 31, 2019
Derivative notional amount			$	5,550					$	4,550
Weighted average:
Remaining maturity (in years)			2.8						3.0
Receive rate			1.87		%				1.94		%
Pay rate (a)			0.17						1.71

(a)Variable rates paid on receive fixed swaps designated as cash flow hedges are based on one-month LIBOR rates in effect at June 30, 2020 and December 31, 2019.

Fair value swaps - receive fixed/pay floating rate on medium- and long-term debt:

(dollar amounts in millions)			June 30, 2020						December 31, 2019
Derivative notional amount			$	2,650					$	3,325
Carrying value of hedged items (a)			2,971						3,469
Weighted average:
Remaining maturity (in years)			5.1						4.6
Receive rate			3.68		%				3.44		%
Pay rate (b)			1.54						2.80

(a)Included $322 million and $146 million of cumulative hedging adjustments at June 30, 2020 and December 31, 2019, respectively, which included $6 million and $7 million, respectively, of hedging adjustment on a discontinued hedging relationship.

(b)Variable rates paid on receive fixed swaps designated as fair value hedges are based on one- and six-month LIBOR rates in effect at June 30, 2020 and December 31, 2019.

Foreign exchange rate risk arises from changes in the value of certain assets and liabilities denominated in foreign currencies. The Corporation employs spot and forward contracts in addition to swap contracts to manage exposure to these and other risks. These instruments are used as economic hedges, and net gains or losses are included in other noninterest income in the Consolidated Statements of Comprehensive Income.

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Notes to Consolidated Financial Statements (unaudited)

Comerica Incorporated and Subsidiaries

Customer-Initiated and Other

The Corporation enters into derivative transactions at the request of customers and generally takes offsetting positions with dealer counterparties to mitigate the inherent market risk. Income primarily results from the spread between the customer derivative and the offsetting dealer position.

For customer-initiated foreign exchange contracts where offsetting positions have not been taken, the Corporation manages the remaining inherent market risk through individual foreign currency position limits and aggregate value-at-risk limits. These limits are established annually and reviewed quarterly. For those customer-initiated derivative contracts which were not offset or where the Corporation holds a position within the limits described above, the Corporation recognized no significant gains or losses in other noninterest income in the Consolidated Statements of Comprehensive Income for both the three- and six-month periods ended June 30, 2020 and 2019.

Fair values of customer-initiated and other derivative instruments represent the net unrealized gains or losses on such contracts and are recorded in the Consolidated Balance Sheets. Changes in fair value are recognized in the Consolidated Statements of Comprehensive Income. The net gains recognized in income on customer-initiated derivative instruments, net of the impact of offsetting positions, were as follows.

									Three Months Ended June 30,																		Six Months Ended June 30,
(in millions)						Location of Gain			2020						2019						2020						2019
Interest rate contracts						Other noninterest income			$	8					$	6					$	16					$	12
Energy contracts						Other noninterest income			2						2						3						3
Foreign exchange contracts						Foreign exchange income			9						11						20						22
Total									$	19					$	19					$	39					$	37

Credit-Related Financial Instruments

The Corporation issues off-balance sheet financial instruments in connection with commercial and consumer lending activities. The Corporation’s credit risk associated with these instruments is represented by the contractual amounts indicated in the following table.

(in millions)			June 30, 2020						December 31, 2019
Unused commitments to extend credit:
Commercial and other			$	22,588					$	23,681
Bankcard, revolving check credit and home equity loan commitments			3,275						3,180
Total unused commitments to extend credit			$	25,863					$	26,861
Standby letters of credit			$	3,185					$	3,320
Commercial letters of credit			19						18

The Corporation maintains an allowance to cover current expected credit losses on lending-related commitments, including unused commitments to extend credit, letters of credit and financial guarantees. The allowance for credit losses on lending-related commitments, included in accrued expenses and other liabilities on the Consolidated Balance Sheets, was $59 million and $31 million at June 30, 2020 and December 31, 2019, respectively.

Unused Commitments to Extend Credit

Commitments to extend credit are legally binding agreements to lend to a customer, provided there is no violation of any condition established in the contract. These commitments generally have fixed expiration dates or other termination clauses and may require payment of a fee. Since many commitments expire without being drawn upon, the total contractual amount of commitments does not necessarily represent future cash requirements of the Corporation. Commercial and other unused commitments are primarily variable rate commitments. The allowance for credit losses on lending-related commitments included $47 million at June 30, 2020 and $25 million at December 31, 2019 for current expected credit losses on the Corporation’s unused commitments to extend credit.

Standby and Commercial Letters of Credit

Standby letters of credit represent conditional obligations of the Corporation which guarantee the performance of a customer to a third party. Standby letters of credit are primarily issued to support public and private borrowing arrangements, including commercial paper, bond financing and similar transactions. Commercial letters of credit are issued to finance foreign or domestic trade transactions. These contracts expire in decreasing amounts through the year 2028. The Corporation may enter

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Notes to Consolidated Financial Statements (unaudited)

Comerica Incorporated and Subsidiaries

into participation arrangements with third parties that effectively reduce the maximum amount of future payments which may be required under standby and commercial letters of credit. These risk participations covered $163 million and $161 million, respectively, of the $3.2 billion and $3.3 billion standby and commercial letters of credit outstanding at June 30, 2020 and December 31, 2019, respectively.

The carrying value of the Corporation’s standby and commercial letters of credit, included in accrued expenses and other liabilities on the Consolidated Balance Sheets, totaled $34 million at June 30, 2020, including $22 million in deferred fees and $12 million in the allowance for credit losses on lending-related commitments. At December 31, 2019, the comparable amounts were $32 million, $26 million and $6 million, respectively.

The following table presents a summary of criticized standby and commercial letters of credit at June 30, 2020 and December 31, 2019. The Corporation's criticized list is generally consistent with the Special Mention, Substandard and Doubtful categories defined by regulatory authorities. The Corporation manages credit risk through underwriting, periodically reviewing and approving its credit exposures using Board committee approved credit policies and guidelines.

(dollar amounts in millions)			June 30, 2020						December 31, 2019
Total criticized standby and commercial letters of credit			$	83					$	44
As a percentage of total outstanding standby and commercial letters of credit			2.6		%				1.3		%

Other Credit-Related Financial Instruments

The Corporation enters into credit risk participation agreements, under which the Corporation assumes credit exposure associated with a borrower’s performance related to certain interest rate derivative contracts. The Corporation is not a party to the interest rate derivative contracts and only enters into these credit risk participation agreements in instances in which the Corporation is also a party to the related loan participation agreements for such borrowers. The Corporation manages credit risk on credit risk participation agreements by monitoring the creditworthiness of the borrowers, based on the normal credit review process as if the Corporation had entered into the derivative instruments directly with the borrowers. The notional amount of such credit risk participation agreements reflects the pro-rata share of the derivative instrument, consistent with the Corporation's share of the related participated loan. As of June 30, 2020 and December 31, 2019, the total notional amount of the credit risk participation agreements was approximately $1.1 billion and $786 million, respectively, and the fair value was $3 million at June 30, 2020 and insignificant at December 31, 2019. The maximum estimated exposure to these agreements, as measured by projecting a maximum value of the guaranteed derivative instruments, assuming 100 percent default by all obligors on the maximum values, was $76 million and $20 million at June 30, 2020 and December 31, 2019, respectively. In the event of default, the lead bank has the ability to liquidate the assets of the borrower, in which case the lead bank would be required to return a percentage of the recouped assets to the participating banks. As of June 30, 2020, the weighted average remaining maturity of outstanding credit risk participation agreements was 4.7 years.

NOTE 6 - VARIABLE INTEREST ENTITIES (VIEs)

The Corporation evaluates its interest in certain entities to determine if these entities meet the definition of a VIE and whether the Corporation is the primary beneficiary and should consolidate the entity based on the variable interests it held both at inception and when there is a change in circumstances that requires a reconsideration.

The Corporation holds ownership interests in funds in the form of limited partnerships or limited liability companies (LLCs) investing in affordable housing projects that qualify for the low-income housing tax credit (LIHTC). The Corporation also directly invests in limited partnerships and LLCs which invest in community development projects, which generate similar tax credits to investors (other tax credit entities). As an investor, the Corporation obtains income tax credits and deductions from the operating losses of these tax credit entities. These tax credit entities meet the definition of a VIE; however, the Corporation is not the primary beneficiary of the entities, as the general partner or the managing member has both the power to direct the activities that most significantly impact the economic performance of the entities and the obligation to absorb losses or the right to receive benefits that could be significant to the entities.

The Corporation accounts for its interests in LIHTC entities using the proportional amortization method. Ownership interests in other tax credit entities are accounted for under either the cost or equity method. Exposure to loss as a result of the Corporation's involvement in LIHTC entities and other tax credit entities at June 30, 2020 was limited to $451 million and $10 million, respectively.

Investment balances, including all legally binding commitments to fund future investments, are included in accrued income and other assets on the Consolidated Balance Sheets. A liability is recognized in accrued expenses and other liabilities

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Notes to Consolidated Financial Statements (unaudited)

Comerica Incorporated and Subsidiaries

on the Consolidated Balance Sheets for all legally binding unfunded commitments to fund tax credit entities ($173 million at June 30, 2020). Amortization and other write-downs of LIHTC investments are presented on a net basis as a component of the provision for income taxes on the Consolidated Statements of Comprehensive Income, while amortization and write-downs of other tax credit investments are recorded in other noninterest income. The income tax credits and deductions are recorded as a reduction of income tax expense and a reduction of federal income taxes payable.

The Corporation provided no financial or other support that was not contractually required to any of the above VIEs during the six months ended June 30, 2020 and 2019.

The following table summarizes the impact of these tax credit entities on the Corporation’s Consolidated Statements of Comprehensive Income.

			Three Months Ended June 30,																		Six Months Ended June 30,
(in millions)			2020						2019						2020						2019
Other noninterest income:
Amortization of other tax credit investments			$	—					$	—					$	—					$	1
Provision for income taxes:
Amortization of LIHTC investments			17						17						34						32
Low income housing tax credits			(16)						(15)						(32)						(30)
Other tax benefits related to tax credit entities			(3)						(4)						(7)						(7)
Total provision for income taxes			$	(2)					$	(2)					$	(5)					$	(5)

For further information on the Corporation’s consolidation policy, see Note 1 to the consolidated financial statements in the Corporation's 2019 Annual Report.

NOTE 7 - MEDIUM- AND LONG-TERM DEBT

Medium- and long-term debt is summarized as follows:

(in millions)			June 30, 2020						December 31, 2019
Parent company
Subordinated notes:
3.80% subordinated notes due 2026 (a)			$	284					$	264
Medium- and long-term notes:
3.70% notes due 2023 (a)			917						884
4.00% notes due 2029 (a)			647						587
Total medium- and long-term notes			1,564						1,471
Total parent company			1,848						1,735
Subsidiaries
Subordinated notes:
4.00% subordinated notes due 2025 (a)			383						360
7.875% subordinated notes due 2026 (a)			213						202
Total subordinated notes			596						562
Medium- and long-term notes:
2.50% notes due 2020 (a)			—						674
2.50% notes due 2024 (a)			527						498
Total medium- and long-term notes			527						1,172
FHLB advances:
Floating-rate based on FHLB auction rate due 2026			2,800						2,800
Floating-rate based on FHLB auction rate due 2028			750						1,000
Total FHLB advances			3,550						3,800
Total subsidiaries			4,673						5,534
Total medium- and long-term debt			$	6,521					$	7,269

(a)The fixed interest rates on these notes have been swapped to a variable rate and designated in a hedging relationship. Accordingly, carrying value has been adjusted to reflect the change in the fair value of the debt as a result of changes in the benchmark rate.

        Subordinated notes with remaining maturities greater than one year qualify as Tier 2 capital.

        Comerica Bank (the Bank), a wholly-owned subsidiary of the Corporation, is a member of the FHLB, which provides short- and long-term funding to its members through advances collateralized by real estate-related assets. The interest rates on

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Comerica Incorporated and Subsidiaries

the FHLB advances resets between four and eight weeks, based on the FHLB auction rate. At June 30, 2020, the weighted-average rate on the FHLB advances was 0.31%. Each note may be prepaid in full, without penalty, at each scheduled reset date. Borrowing capacity is contingent on the amount of collateral available to be pledged to the FHLB. At June 30, 2020, $18.3 billion of real estate-related loans and $5.2 billion of investment securities were pledged to the FHLB as collateral for outstanding short- and long-term advances of $750 million and $3.6 billion, respectively, with an additional capacity for potential future borrowings of approximately $10.1 billion.

        Unamortized debt issuance costs deducted from the carrying amount of medium- and long-term debt totaled $11 million at June 30, 2020 and $12 million at December 31, 2019.

NOTE 8 - ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS)

The following table presents a reconciliation of the changes in the components of accumulated other comprehensive income (loss) and details the components of other comprehensive income (loss) for the six months ended June 30, 2020 and 2019, including the amount of income tax expense (benefit) allocated to each component of other comprehensive income (loss).

			Six Months Ended June 30,
(in millions)			2020						2019
Accumulated net unrealized gains on investment securities:
Balance at beginning of period, net of tax			$	65					$	(138)
Net unrealized holding gains arising during the period			286						229
Less: Provision for income taxes			68						54
Net unrealized holding gains arising during the period, net of tax			218						175
Less:
Net realized losses included in net securities losses			—						(8)
Less: Benefit for income taxes			—						(2)
Reclassification adjustment for net securities losses included in net income, net of tax			—						(6)
Change in net unrealized gains on investment securities, net of tax			218						181
Balance at end of period, net of tax			$	283					$	43
Accumulated net gains on cash flow hedges:
Balance at beginning of period, net of tax			$	34					$	—
Net cash flow hedge gains arising during the period			233						51
Less: Provision for income taxes			56						12
Change in net cash flow hedge gains arising during the period, net of tax			177						39
Less:
Net cash flow hedge gains (losses) included in interest and fees on loans			22						(1)
Less: Provision for income taxes			7						—
Reclassification adjustment for net cash flow hedge gains (losses) included in net income, net of tax			15						(1)
Change in net cash flow hedge gains, net of tax			162						40
Balance at end of period, net of tax (a)			$	196					$	40
Accumulated defined benefit pension and other postretirement plans adjustment:
Balance at beginning of period, net of tax			$	(334)					$	(471)
Amortization of actuarial net loss			31						21
Amortization of prior service credit			(14)						(13)
Amounts recognized in other noninterest expenses			17						8
Less: Provision for income taxes			4						2
Change in defined benefit pension and other postretirement plans adjustment, net of tax			13						6
Balance at end of period, net of tax			$	(321)					$	(465)
Total accumulated other comprehensive income (loss) at end of period, net of tax			$	158					$	(382)

(a)The Corporation expects to reclassify $73 million of net gains, net of tax, from accumulated other comprehensive income to earnings over the next twelve months if interest yield curves and notional amounts remain at June 30, 2020 levels.

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Comerica Incorporated and Subsidiaries

NOTE 9 - NET INCOME PER COMMON SHARE

Basic and diluted net income per common share are presented in the following table.

			Three Months Ended June 30,																		Six Months Ended June 30,
(in millions, except per share data)			2020						2019						2020						2019
Basic and diluted
Net income			$	113					$	298					$	48					$	637
Less: Income allocated to participating securities			1						1						1						3
Net income attributable to common share			$	112					$	297					$	47					$	634
Basic average common shares			139						152						140						155
Basic net income per common share			$	0.81					$	1.95					$	0.34					$	4.10
Basic average common shares			139						152						140						155
Dilutive common stock equivalents:
Net effect of the assumed exercise of stock awards			—						1						1						1
Diluted average common shares			139						153						141						156
Diluted net income per common share			$	0.80					$	1.94					$	0.34					$	4.06

The following average shares related to outstanding options to purchase shares of common stock were not included in the computation of diluted net income per common share because the options were anti-dilutive for the period.

			Three Months Ended June 30,																		Six Months Ended June 30,
			2020						2019						2020						2019
Average outstanding options			2,056,133						470,162						1,633,078						446,610
Range of exercise prices			$39.10 - $95.25						$79.01 - $95.25						$39.10 - $95.25						$79.01 - $95.25

In May 2020, the Corporation issued and sold 400,000 depositary shares, each representing a 1/100th ownership interest in a share of 5.625% Fixed-Rate Reset Non-Cumulative Perpetual Preferred Stock, Series A, without par value, with a liquidation preference of $100,000 per share (equivalent of $1,000 per depositary share). Holders of the depositary shares will be entitled to all proportional rights and preferences of the Series A preferred stock (including dividend, voting, redemption and liquidation rights). The $400 million issuance yielded $395 million in proceeds net of underwriting discounts and offering expenses. Dividends on the Series A preferred stock will accrue on a non-cumulative basis and will be payable in arrears when, as and if authorized by the Corporation’s board of directors or a duly authorized committee of the board and declared by the Corporation, on the first day of January, April, July, and October of each year, commencing on October 1, 2020. Under the terms of the Series A preferred stock, the ability of the Corporation to pay dividends on, make distributions with respect to, or to repurchase, redeem or acquire its common stock or any other stock ranking on parity with or junior to the Series A preferred stock, is subject to restrictions in the event that the Corporation does not declare and either pay or set aside a sum sufficient for payment of dividends on the Series A Preferred Stock for the immediately preceding dividend period. The Series A preferred stock is perpetual and has no maturity date, but is redeemable at specified times subject to regulatory considerations.

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Comerica Incorporated and Subsidiaries

NOTE 10 - EMPLOYEE BENEFIT PLANS

Net periodic defined benefit cost (credit) is comprised of service cost and other components of net benefit cost (credit). Service cost is included in salaries and benefits expense and other components of net benefit cost (credit) are included in other noninterest expenses on the Consolidated Statements of Comprehensive Income. For further information on the Corporation's employee benefit plans, refer to Note 17 to the consolidated financial statements in the Corporation's 2019 Annual Report.

The components of net periodic benefit cost (credit) for the Corporation's qualified pension plan, non-qualified pension plan and postretirement benefit plan are as follows.

Qualified Defined Benefit Pension Plan			Three Months Ended June 30,																		Six Months Ended June 30,
(in millions)			2020						2019						2020						2019
Service cost			$	8					$	7					$	16					$	15
Other components of net benefit credit:
Interest cost			17						20						35						40
Expected return on plan assets			(42)						(41)						(85)						(83)
Amortization of prior service credit			(5)						(4)						(10)						(9)
Amortization of net loss			13						8						27						17
Total other components of net benefit credit			(17)						(17)						(33)						(35)
Net periodic defined benefit credit			$	(9)					$	(10)					$	(17)					$	(20)

Non-Qualified Defined Benefit Pension Plan			Three Months Ended June 30,																		Six Months Ended June 30,
(in millions)			2020						2019						2020						2019
Service cost			$	—					$	1					$	1					$	2
Other components of net benefit cost:
Interest cost			2						2						4						4
Amortization of prior service credit			(2)						(2)						(4)						(4)
Amortization of net loss			2						2						4						4
Total other components of net benefit cost			2						2						4						4
Net periodic defined benefit cost			$	2					$	3					$	5					$	6

Postretirement Benefit Plan			Three Months Ended June 30,																		Six Months Ended June 30,
(in millions)			2020						2019						2020						2019
Other components of net benefit credit:
Interest cost			$	—					$	—					$	—					$	1
Expected return on plan assets			(1)						—						(1)						(1)
Net periodic defined benefit credit			$	(1)					$	—					$	(1)					$	—

NOTE 11 - INCOME TAXES AND TAX-RELATED ITEMS

At June 30, 2020, net unrecognized tax benefits were $18 million, compared to $17 million at December 31, 2019. The Corporation anticipates that it is reasonably possible that final settlement of federal and state tax issues will result in a decrease in net unrecognized tax benefits of $1 million within the next twelve months. Included in accrued expenses and other liabilities on the Consolidated Balance Sheets was a liability for tax-related interest and penalties of $6 million and $8 million on June 30, 2020 and December 31, 2019, respectively.

Net deferred tax assets were $11 million at June 30, 2020, compared to $42 million at December 31, 2019, primarily driven by increases to deferred tax liabilities related to unrealized losses on investment securities available-for-sale and net hedging gains, partially offset by increases to deferred tax assets related to the allowance for loan losses and allowance for depreciation. Included in deferred tax assets at both June 30, 2020 and December 31, 2019 were $3 million of state net operating loss carryforwards, which expire between 2020 and 2029. The Corporation believes that it is more likely than not that the benefit from certain of these state net operating loss carryforwards will not be realized and, accordingly, maintained a valuation allowance of $3 million at both June 30, 2020 and December 31, 2019. The determination regarding valuation allowance was based on evidence of loss carryback capacity, projected future reversals of existing taxable temporary differences to absorb the deferred tax assets and assumptions made regarding future events.

In the ordinary course of business, the Corporation enters into certain transactions that have tax consequences. From time to time, the Internal Revenue Service (IRS) or other tax jurisdictions may review and/or challenge specific interpretive tax

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Comerica Incorporated and Subsidiaries

positions taken by the Corporation with respect to those transactions. The Corporation believes its tax returns were filed based upon applicable statutes, regulations and case law in effect at the time of the transactions. The IRS or other tax jurisdictions, an administrative authority or a court, if presented with the transactions, could disagree with the Corporation’s interpretation of the tax law.

Based on current knowledge and probability assessment of various potential outcomes, the Corporation believes that current tax reserves are adequate, and the amount of any potential incremental liability arising is not expected to have a material adverse effect on the Corporation’s consolidated financial condition or results of operations. Probabilities and outcomes are reviewed as events unfold, and adjustments to the reserves are made when necessary.

NOTE 12 - CONTINGENT LIABILITIES

Legal Proceedings

As previously reported in the Corporation's Form 10-K for the year ended December 31, 2019 and Form 10-Q for the period ended March 31, 2020, Comerica Bank, a wholly-owned subsidiary of the Corporation, was named in November 2011 as a third-party defendant in Butte Local Development v. Masters Group v. Comerica Bank (the case), for lender liability. The case was initially tried in January 2014, in the Montana Second District Judicial Court for Silver Bow County in Butte, Montana. On January 17, 2014, a jury found for Masters, resulting in an award against the Bank. On July 1, 2015, after an appeal filed by the Bank, the Montana Supreme Court reversed the judgment against the Bank and remanded the case for a new trial with instructions that Michigan contract law should apply and dismissing all other claims. In January 2017, the case was retried, without a jury, in the Second District Court, Silver Bow County, Montana. In November 2019, the court found the Bank breached its forbearance agreement. On January 17, 2020, the court conducted a hearing on the amount of costs and interest that Masters is entitled to recover. On June 12, 2020, the court found Masters is entitled to attorneys' fees, interest and costs. The Bank is considering its options, including additional appeals. Management believes that current reserves related to this case are adequate in the event of an adverse outcome.

The Corporation and certain of its subsidiaries are subject to various other pending or threatened legal proceedings arising out of the normal course of business or operations. The Corporation believes it has meritorious defenses to the claims asserted against it in its other currently outstanding legal proceedings and, with respect to such legal proceedings, intends to continue to defend itself vigorously, litigating or settling cases according to management’s judgment as to what is in the best interests of the Corporation and its shareholders. Settlement may result from the Corporation's determination that it may be more prudent financially to settle, rather than litigate, and should not be regarded as an admission of liability. On at least a quarterly basis, the Corporation assesses its potential liabilities and contingencies in connection with outstanding legal proceedings utilizing the latest information available. On a case-by-case basis, reserves are established for those legal claims for which it is probable that a loss will be incurred either as a result of a settlement or judgment, and the amount of such loss can be reasonably estimated. The actual costs of resolving these claims may be substantially higher or lower than the amounts reserved. Based on current knowledge, and after consultation with legal counsel, management believes current reserves are adequate, and the amount of any incremental liability arising from these matters is not expected to have a material adverse effect on the Corporation’s consolidated financial condition, results of operations or cash flows. Legal fees of $5 million and $4 million were included in other noninterest expenses on the Consolidated Statements of Comprehensive Income for the three-month periods ended June 30, 2020 and 2019, respectively, and $7 million and $5 million for the six-month periods ended June 30, 2020 and 2019, respectively.

For matters where a loss is not probable, the Corporation has not established legal reserves. The Corporation believes the estimate of the aggregate range of reasonably possible losses, in excess of reserves established, for all legal proceedings in which it is involved is from zero to approximately $46 million at June 30, 2020. This estimated aggregate range of reasonably possible losses is based upon currently available information for those proceedings in which the Corporation is involved, taking into account the Corporation’s best estimate of such losses for those cases for which such estimate can be made. For certain cases, the Corporation does not believe that an estimate can currently be made. The Corporation’s estimate involves significant judgment, given the varying stages of the proceedings (including the fact many are currently in preliminary stages), the existence in certain proceedings of multiple defendants (including the Corporation) whose share of liability has yet to be determined, the numerous yet-unresolved issues in many of the proceedings (including issues regarding class certification and the scope of many of the claims) and the attendant uncertainty of the various potential outcomes of such proceedings. Accordingly, the Corporation’s estimate will change from time to time, and actual losses may be more or less than the current estimate.

In the event of unexpected future developments, it is possible the ultimate resolution of these matters, if unfavorable, may be material to the Corporation's consolidated financial condition, results of operations or cash flows.

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Comerica Incorporated and Subsidiaries

For information regarding income tax contingencies, refer to Note 11.

NOTE 13 - BUSINESS SEGMENT INFORMATION

The Corporation has strategically aligned its operations into three major business segments: the Commercial Bank, the Retail Bank and Wealth Management. These business segments are differentiated based on the type of customer and the related products and services provided. In addition to the three major business segments, the Finance Division is also reported as a segment. Business segment results are produced by the Corporation’s internal management accounting system. This system measures financial results based on the internal business unit structure of the Corporation. The performance of the business segments is not comparable with the Corporation's consolidated results and is not necessarily comparable with similar information for any other financial institution. Additionally, because of the interrelationships of the various segments, the information presented is not indicative of how the segments would perform if they operated as independent entities. The management accounting system assigns balance sheet and income statement items to each business segment using certain methodologies, which are regularly reviewed and refined. From time to time, the Corporation may make reclassifications among the segments to more appropriately reflect management's current view of the segments, and methodologies may be modified as the management accounting system is enhanced and changes occur in the organizational structure and/or product lines. For comparability purposes, amounts in all periods are based on business unit structure and methodologies in effect at June 30, 2020.

The following discussion provides information about the activities of each business segment. A discussion of the financial results and the factors impacting performance can be found in the section entitled "Business Segments" in the financial review.

The Commercial Bank meets the needs of small and middle market businesses, multinational corporations and governmental entities by offering various products and services including commercial loans and lines of credit, deposits, cash management, capital market products, international trade finance, letters of credit, foreign exchange management services and loan syndication services.

The Retail Bank includes a full range of personal financial services, consisting of consumer lending, consumer deposit gathering and mortgage loan origination. This business segment offers a variety of consumer products including deposit accounts, installment loans, credit cards, student loans, home equity lines of credit and residential mortgage loans.

Wealth Management offers products and services consisting of fiduciary services, private banking, retirement services, investment management and advisory services, investment banking and brokerage services. This business segment also offers the sale of annuity products, as well as life, disability and long-term care insurance products.

The Finance segment includes the Corporation’s securities portfolio and asset and liability management activities. This segment is responsible for managing the Corporation’s funding, liquidity and capital needs, performing interest sensitivity analysis and executing various strategies to manage the Corporation’s exposure to liquidity, interest rate risk and foreign exchange risk.

The Other category includes the income and expense impact of equity and cash, tax benefits not assigned to specific business segments, charges of an unusual or infrequent nature that are not reflective of the normal operations of the business segments and miscellaneous other expenses of a corporate nature.

For further information on the methodologies which form the basis for these results refer to Note 22 to the consolidated financial statements in the Corporation's 2019 Annual Report.

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Comerica Incorporated and Subsidiaries

Business segment financial results are as follows:

			Commercial Bank						Retail Bank						Wealth Management						Finance						Other						Total
(dollar amounts in millions)
Three Months Ended June 30, 2020
Earnings summary:
Net interest income (expense)			$	402					$	120					$	40					$	(95)					$	4					$	471
Provision for credit losses			117						5						16						—						—						138
Noninterest income			144						24						66						11						2						247
Noninterest expenses			207						155						73						1						4						440
Provision (benefit) for income taxes			47						(4)						3						(20)						1						27
Net income (loss)			$	175					$	(12)					$	14					$	(65)					$	1					$	113
Net credit-related charge-offs			$	48					$	1					$	1					$	—					$	—					$	50
Selected average balances:
Assets			$	47,392					$	3,306					$	5,191					$	14,500					$	11,255					$	81,644
Loans			45,914						2,479						5,077						—						28						53,498
Deposits			36,318						22,647						4,217						950						150						64,282
Statistical data:
Return on average assets (a)			1.49		%				(0.21)		%				1.00		%				n/m						n/m						0.55		%
Efficiency ratio (b)			37.67						107.15						69.86						n/m						n/m						61.14
Three Months Ended June 30, 2019
Earnings summary:
Net interest income (expense)			$	420					$	146					$	46					$	(23)					$	14					$	603
Provision for credit losses			52						1						(5)						—						(4)						44
Noninterest income			136						33						68						13						—						250
Noninterest expenses			195						147						67						—						15						424
Provision (benefit) for income taxes			71						7						13						(4)						—						87
Net income (loss)			$	238					$	24					$	39					$	(6)					$	3					$	298
Net credit-related charge-offs (recoveries)			$	35					$	—					$	(2)					$	—					$	—					$	33
Selected average balances:
Assets			$	45,321					$	2,839					$	5,071					$	13,907					$	4,114					$	71,252
Loans			43,932						2,107						4,930						—						(6)						50,963
Deposits			28,251						20,649						3,740						2,174						181						54,995
Statistical data:
Return on average assets (a)			2.11		%				0.44		%				3.10		%				n/m						n/m						1.68		%
Efficiency ratio (b)			34.98						82.26						58.99						n/m						n/m						49.65

(a)Return on average assets is calculated based on the greater of average assets or average liabilities and attributed equity.

(b)Noninterest expenses as a percentage of the sum of net interest income and noninterest income excluding net gains (losses) from securities and a derivative contract tied to the conversion rate of Visa Class B shares.

n/m – not meaningful

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Comerica Incorporated and Subsidiaries

			Commercial Bank						Retail Bank						Wealth Management						Finance						Other						Total
(dollar amounts in millions)
Six Months Ended June 30, 2020
Earnings summary:
Net interest income (expense)			$	782					$	245					$	81					$	(139)					$	15					$	984
Provision for credit losses			513						8						28						—						—						549
Noninterest income			271						52						136						25						—						484
Noninterest expenses			401						304						145						1						14						865
Provision (benefit) for income taxes			27						(4)						9						(28)						2						6
Net income (loss)			$	112					$	(11)					$	35					$	(87)					$	(1)					$	48
Net credit-related charge-offs			$	131					$	2					$	1					$	—					$	—					$	134
Selected average balances:
Assets			$	45,823					$	3,085					$	5,134					$	14,393					$	9,019					$	77,454
Loans			44,253						2,277						5,007						—						14						51,551
Deposits			33,274						21,921						4,120						1,043						166						60,524
Statistical data:
Return on average assets (a)			0.49		%				(0.10)		%				1.34		%				n/m						n/m						0.12		%
Efficiency ratio (b)			38.05						101.41						67.00						n/m						n/m						58.80
Six Months Ended June 30, 2019
Earnings summary:
Net interest income (expense)			$	832					$	292					$	93					$	(37)					$	29					$	1,209
Provision for credit losses			46						(3)						(10)						—						(2)						31
Noninterest income			272						64						132						17						3						488
Noninterest expenses			393						292						139						1						32						857
Provision (benefit) for income taxes			153						16						23						(8)						(12)						172
Net income (loss)			$	512					$	51					$	73					$	(13)					$	14					$	637
Net credit-related charge-offs (recoveries)			$	47					$	—					$	(3)					$	—					$	—					$	44
Selected average balances:
Assets			$	44,619					$	2,826					$	5,121					$	13,747					$	4,202					$	70,515
Loans			43,241						2,105						4,983						—						(6)						50,323
Deposits			28,356						20,560						3,770						1,655						157						54,498
Statistical data:
Return on average assets (a)			2.31		%				0.49		%				2.88		%				n/m						n/m						1.82		%
Efficiency ratio (b)			35.61						81.80						61.67						n/m						n/m						50.23

(a)Return on average assets is calculated based on the greater of average assets or average liabilities and attributed equity.

(b)Noninterest expenses as a percentage of the sum of net interest income and noninterest income excluding net gains (losses) from securities and a derivative contract tied to the conversion rate of Visa Class B shares.

n/m – not meaningful

The Corporation operates in three primary markets - Texas, California and Michigan, as well as in Arizona and Florida, with select businesses operating in several other states and in Canada and Mexico. The Corporation produces market segment results for the Corporation’s three primary geographic markets as well as Other Markets. Other Markets includes Florida, Arizona, the International Finance division and businesses with a national perspective. The Finance & Other category includes the Finance segment and the Other category as previously described. Market segment results are provided as supplemental information to the business segment results and may not meet all operating segment criteria as set forth in GAAP. For comparability purposes, amounts in all periods are based on market segments and methodologies in effect at June 30, 2020.

A discussion of the financial results and the factors impacting performance can be found in the section entitled "Market Segments" in the financial review.

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Comerica Incorporated and Subsidiaries

Market segment financial results are as follows:

			Michigan						California						Texas						Other Markets						Finance & Other						Total
(dollar amounts in millions)
Three Months Ended June 30, 2020
Earnings summary:
Net interest income (expense)			$	159					$	176					$	116					$	111					$	(91)					$	471
Provision for credit losses			40						51						31						16						—						138
Noninterest income			64						36						30						104						13						247
Noninterest expenses			139						103						91						102						5						440
Provision (benefit) for income taxes			8						13						4						21						(19)						27
Net income (loss)			$	36					$	45					$	20					$	76					$	(64)					$	113
Net credit-related charge-offs			$	—					$	4					$	46					$	—					$	—					$	50
Selected average balances:
Assets			$	13,643					$	18,948					$	11,597					$	11,732					$	25,724					$	81,644
Loans			13,014						18,663						11,184						10,640						(3)						53,498
Deposits			23,460						18,463						10,209						11,050						1,100						64,282
Statistical data:
Return on average assets (a)			0.59		%				0.93		%				0.68		%				2.53		%				n/m						0.55		%
Efficiency ratio (b)			62.08						48.61						61.88						47.41						n/m						61.14
Three Months Ended June 30, 2019
Earnings summary:
Net interest income (expense)			$	186					$	208					$	124					$	94					$	(9)					$	603
Provision for credit losses			(10)						(4)						49						13						(4)						44
Noninterest income			72						40						34						91						13						250
Noninterest expenses			134						99						84						92						15						424
Provision (benefit) for income taxes			30						39						6						16						(4)						87
Net income (loss)			$	104					$	114					$	19					$	64					$	(3)					$	298
Net credit-related charge-offs			$	—					$	7					$	26					$	—					$	—					$	33
Selected average balances:
Assets			$	13,239					$	19,108					$	11,342					$	9,542					$	18,021					$	71,252
Loans			12,704						18,806						10,684						8,775						(6)						50,963
Deposits			19,816						16,314						8,668						7,842						2,355						54,995
Statistical data:
Return on average assets (a)			2.01		%				2.38		%				0.69		%				2.75		%				n/m						1.68		%
Efficiency ratio (b)			52.04						40.07						52.86						49.36						n/m						49.65

(a)Return on average assets is calculated based on the greater of average assets or average liabilities and attributed equity.

(b)Noninterest expenses as a percentage of the sum of net interest income and noninterest income excluding net gains (losses) from securities and a derivative contract tied to the conversion rate of Visa Class B shares.

n/m – not meaningful.

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Comerica Incorporated and Subsidiaries

			Michigan						California						Texas						Other Markets						Finance & Other						Total
(dollar amounts in millions)
Six Months Ended June 30, 2020
Earnings summary:
Net interest income (expense)			$	322					$	358					$	231					$	197					$	(124)					$	984
Provision for credit losses			64						102						321						62						—						549
Noninterest income			136						72						60						191						25						484
Noninterest expenses			279						201						175						195						15						865
Provision (benefit) for income taxes			23						30						(46)						25						(26)						6
Net income (loss)			$	92					$	97					$	(159)					$	106					$	(88)					$	48
Net credit-related charge-offs			$	3					$	15					$	116					$	—					$	—					$	134
Selected average balances:
Assets			$	13,269					$	18,664					$	11,371					$	10,754					$	23,396					$	77,454
Loans			12,601						18,346						10,870						9,735						(1)						51,551
Deposits			22,104						17,965						9,705						9,541						1,209						60,524
Statistical data:
Return on average assets (a)			0.81		%				1.02		%				(2.82)		%				1.99		%				n/m						0.12		%
Efficiency ratio (b)			60.46						46.77						60.07						50.25						n/m						58.80
Six Months Ended June 30, 2019
Earnings summary:
Net interest income (expense)			$	373					$	411					$	248					$	185					$	(8)					$	1,209
Provision for credit losses			(5)						(5)						38						5						(2)						31
Noninterest income			144						80						66						178						20						488
Noninterest expenses			273						199						169						183						33						857
Provision (benefit) for income taxes			56						76						25						35						(20)						172
Net income			$	193					$	221					$	82					$	140					$	1					$	637
Net credit-related charge-offs (recoveries)			$	4					$	4					$	39					$	(3)					$	—					$	44
Selected average balances:
Assets			$	13,157					$	19,020					$	11,128					$	9,261					$	17,949					$	70,515
Loans			12,631						18,730						10,474						8,494						(6)						50,323
Deposits			19,854						16,276						8,682						7,874						1,812						54,498
Statistical data:
Return on average assets (a)			1.89		%				2.35		%				1.47		%				3.06		%				n/m						1.82		%
Efficiency ratio (b)			52.85						40.49						53.74						50.30						n/m						50.23

(a)Return on average assets is calculated based on the greater of average assets or average liabilities and attributed equity.

(b)Noninterest expenses as a percentage of the sum of net interest income and noninterest income excluding net gains (losses) from securities and a derivative contract tied to the conversion rate of Visa Class B shares.

n/m – not meaningful.

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Comerica Incorporated and Subsidiaries

NOTE 14 - REVENUE FROM CONTRACTS WITH CUSTOMERS

Revenue from contracts with customers comprises the noninterest income earned by the Corporation in exchange for services provided to customers. The following table presents the composition of revenue from contracts with customers, segregated from other sources of noninterest income, by business segment.

			Commercial Bank						Retail Bank						Wealth Management						Finance & Other						Total
(in millions)
Three Months Ended June 30, 2020
Revenue from contracts with customers:
Card fees			$	59					$	8					$	1					$	—					$	68
Service charges on deposit accounts			30						11						1						—						42
Fiduciary income			—						—						52						—						52
Commercial loan servicing fees (a)			4						—						—						—						4
Brokerage fees			—						—						5						—						5
Other noninterest income (b)			11						2						4						—						17
Total revenue from contracts with customers			104						21						63						—						188
Other sources of noninterest income			40						3						3						13						59
Total noninterest income			$	144					$	24					$	66					$	13					$	247
Three Months Ended June 30, 2019
Revenue from contracts with customers:
Card fees			$	54					$	10					$	1					$	—					$	65
Service charges on deposit accounts			33						17						1						—						51
Fiduciary income			—						—						52						—						52
Commercial loan servicing fees (a)			4						—						—						—						4
Brokerage fees			—						—						7						—						7
Other noninterest income (b)			2						4						4						—						10
Total revenue from contracts with customers			93						31						65						—						189
Other sources of noninterest income			43						2						3						13						61
Total noninterest income			$	136					$	33					$	68					$	13					$	250
Six Months Ended June 30, 2020
Revenue from contracts with customers:
Card fees			$	108					$	17					$	2					$	—					$	127
Service charges on deposit accounts			62						27						2						—						91
Fiduciary income			—						—						106						—						106
Commercial loan servicing fees (a)			8						—						—						—						8
Brokerage fees			—						—						12						—						12
Other noninterest income (b)			15						5						9						—						29
Total revenue from contracts with customers			193						49						131						—						373
Other sources of noninterest income			78						3						5						25						111
Total noninterest income			$	271					$	52					$	136					$	25					$	484
Six Months Ended June 30, 2019
Revenue from contracts with customers:
Card fees			$	107					$	19					$	2					$	—					$	128
Service charges on deposit accounts			66						34						2						—						102
Fiduciary income			—						—						101						—						101
Commercial loan servicing fees (a)			8						—						—						—						8
Brokerage fees			—						—						14						—						14
Other noninterest income (b)			4						7						9						—						20
Total revenue from contracts with customers			185						60						128						—						373
Other sources of noninterest income			87						4						4						20						115
Total noninterest income			$	272					$	64					$	132					$	20					$	488

(a)Included in commercial lending fees on the Consolidated Statements of Comprehensive Income.

(b)Excludes derivative, warrant and other miscellaneous income.

        Adjustments to revenue during the three- and six-month periods ended June 30, 2020 and 2019 for refunds or credits relating to prior periods were not significant.

        Revenue from contracts with customers did not generate significant contract assets and liabilities.

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ITEM 2. Management's Discussion and Analysis of Financial Condition and Results of Operations

FORWARD-LOOKING STATEMENTS

This report includes forward-looking statements as defined in the Private Securities Litigation Reform Act of 1995. In addition, the Corporation may make other written and oral communications from time to time that contain such statements. All statements regarding the Corporation's expected financial position, strategies and growth prospects and general economic conditions expected to exist in the future are forward-looking statements. The words, "anticipates," "believes," "contemplates," "feels," "expects," "estimates," "seeks," "strives," "plans," "intends," "outlook," "forecast," "position," "target," "mission," "assume," "achievable," "potential," "strategy," "goal," "aspiration," "opportunity," "initiative," "outcome," "continue," "remain," "maintain," "on track," "trend," "objective," "looks forward," "projects," "models," and variations of such words and similar expressions, or future or conditional verbs such as "will," "would," "should," "could," "might," "can," "may" or similar expressions, as they relate to the Corporation or its management, are intended to identify forward-looking statements. These forward-looking statements are predicated on the beliefs and assumptions of the Corporation's management based on information known to the Corporation's management as of the date of this report and do not purport to speak as of any other date. Forward-looking statements may include descriptions of plans and objectives of the Corporation's management for future or past operations, products or services and forecasts of the Corporation's revenue, earnings or other measures of economic performance, including statements of profitability, business segments and subsidiaries as well as estimates of credit trends and global stability. Such statements reflect the view of the Corporation's management as of this date with respect to future events and are subject to risks and uncertainties. Should one or more of these risks materialize or should underlying beliefs or assumptions prove incorrect, the Corporation's actual results could differ materially from those discussed. Factors that could cause or contribute to such differences include credit risks (unfavorable developments concerning credit quality; declines or other changes in the businesses or industries of the Corporation's customers, in particular the energy industry; and changes in customer behavior); market risks (changes in monetary and fiscal policies; fluctuations in interest rates and their impact on deposit pricing; and transitions away from LIBOR towards new interest rate benchmarks); liquidity risks (the Corporation's ability to maintain adequate sources of funding and liquidity; reductions in the Corporation's credit rating; and the interdependence of financial service companies); technology risks (cybersecurity risks and heightened legislative and regulatory focus on cybersecurity and data privacy); operational risks (operational, systems or infrastructure failures; reliance on other companies to provide certain key components of business infrastructure; the impact of legal and regulatory proceedings or determinations; losses due to fraud; and controls and procedures failures); compliance risks (changes in regulation or oversight; the effects of stringent capital requirements; and the impacts of future legislative, administrative or judicial changes to tax regulations); financial reporting risks (changes in accounting standards and the critical nature of the Corporation's accounting policies); strategic risks (damage to the Corporation's reputation; the Corporation's ability to utilize technology to efficiently and effectively develop, market and deliver new products and services; competitive product and pricing pressures among financial institutions within the Corporation's markets; the implementation of the Corporation's strategies and business initiatives; management's ability to maintain and expand customer relationships; management's ability to retain key officers and employees; and any future strategic acquisitions or divestitures); and other general risks (changes in general economic, political or industry conditions; the effectiveness of methods of reducing risk exposures; the effects of catastrophic events; impacts from the COVID-19 global pandemic; and the volatility of the Corporation's stock price). The Corporation cautions that the foregoing list of factors is not all-inclusive. For discussion of factors that may cause actual results to differ from expectations, please refer to our filings with the Securities and Exchange Commission. In particular, please refer to “Item 1A. Risk Factors” beginning on page 12 of the Corporation's Annual Report on Form 10-K for the year ended December 31, 2019 and "Item 1A. Risk Factors" beginning on page 65 of the Corporation's Quarterly Report on Form 10-Q for the quarter ended June 30, 2020. Forward-looking statements speak only as of the date they are made. The Corporation does not undertake to update forward-looking statements to reflect facts, circumstances, assumptions or events that occur after the date the forward-looking statements are made. For any forward-looking statements made in this report or in any documents, the Corporation claims the protection of the safe harbor for forward-looking statements contained in the Private Securities Litigation Reform Act of 1995.

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SERVING CUSTOMERS, COLLEAGUES AND COMMUNITIES DURING THE COVID-19 PANDEMIC

        The COVID-19 outbreak has affected countless people world-wide and continues to negatively impact the global economy. While the full effects of the pandemic remain unknown, the Corporation is committed to supporting its customers, colleagues and communities during this difficult time. The Corporation offers hardship relief assistance to customers, including the consideration of various loan payment deferral and fee waiver options, and encourages customers to reach out for assistance to support their individual circumstances. As a Small Business Administration preferred lender, the Corporation was well positioned to assist business customers in accessing funds available through the Paycheck Protection Program (PPP) and other lending initiatives. Through June 30, 2020, the Corporation funded $3.9 billion of PPP loans, granted payment deferrals for $4.5 billion in loans (primarily commercial), including $57 million of loans on their second deferral, and waived overdraft, late payment, ATM and other customer fees. The Corporation has continued to serve customers at banking center drive-throughs and offer lobby hours by appointment while adhering to social distancing standards.

        In response to the pandemic, the Corporation activated its disaster recovery protocol, successfully avoiding significant disruptions to internal and external functions. The Corporation has supported colleagues through additional compensation and benefits to those most impacted by the pandemic, as well as awarded bonuses for extraordinary service in support of the PPP process.

        The Corporation and the Comerica Charitable Foundation have pledged $8 million to support business needs and community service organizations that care for and provide critical services to our communities.

OUTLOOK FOR THIRD QUARTER 2020 COMPARED TO SECOND QUARTER 2020

Based on current management expectations for recessionary conditions:

•Decline in average loans reflects lending to small businesses with a full quarter benefit of PPP, more than offset by decreases in Mortgage Banker Finance, Large Corporate and National Dealer Services.

•Average deposits relatively stable as customers utilize economic stimulus proceeds.

•Decrease in net interest income resulting from a $10 million to $15 million net impact of lower interest rates (assumes one-month London Interbank Offered Rate (LIBOR) of 17 basis points and interest-bearing deposit cost of 20 basis points). Lower loan balances expected to be offset by lower wholesale debt and one additional day.

•Provision for credit losses reflective of economic environment, including the effects resulting from the duration and severity of the COVID-19 pandemic.

•Decline in noninterest income due to reduced card fees related to transaction activity and lower market-based investment banking and derivative fees, partially offset by higher service charges on deposit accounts due to increased activity. Higher securities trading income and deferred compensation levels in second quarter 2020 not expected to repeat.

•Increase in noninterest expenses, reflecting technology and occupancy projects as well as higher charitable contributions and seasonal impacts of marketing and staff insurance expenses, mostly offset by continued expense discipline and reduction in COVID-19-related costs.

•Capital reflects declaration of first preferred stock dividend and a focus on supporting customers' financing needs, as well as maintaining an attractive common dividend.

RESULTS OF OPERATIONS

Net income for the three months ended June 30, 2020 was $113 million, a decrease of $185 million compared to $298 million for the three months ended June 30, 2019. The decrease in net income reflected the net impact of lower short-term rates. Results for the three months ended June 30, 2020 were also impacted by an increase in the provision for credit losses, calculated using the current expected credit loss (CECL) model, which continues to reflect the forecasted impact of the COVID-19 pandemic and continued pressures on the Energy portfolio. Net income for the six months ended June 30, 2020 was $48 million, a decrease of $589 million compared to $637 million for the six months ended June 30, 2019. The decrease in net income was driven by an increase in the provision for credit losses as well as the net impact of lower short-term rates.

Net income per diluted common share was $0.80 and $1.94 for the three months ended June 30, 2020 and 2019, respectively, a decrease of $1.14 per diluted common share. Net income per diluted common share was $0.34 and $4.06 for the six months ended June 30, 2020 and 2019, respectively, a decrease of $3.72 per diluted common share.

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Three Months Ended June 30, 2020 compared to Three Months Ended June 30, 2019

Analysis of Net Interest Income

			Three Months Ended
			June 30, 2020															June 30, 2019
(dollar amounts in millions)			Average Balance			Interest			Average Rate			Average Balance			Interest			Average Rate
Commercial loans (a)			$	33,944		$	271		3.22		%	$	32,607		$	405		4.99		%
Real estate construction loans			3,887			35			3.60			3,319			47			5.74
Commercial mortgage loans			9,800			76			3.12			9,060			116			5.12
Lease financing			592			5			3.34			546			3			2.32
International loans			1,137			10			3.51			1,025			14			5.30
Residential mortgage loans			1,895			17			3.49			1,943			19			3.92
Consumer loans			2,243			20			3.62			2,463			31			5.02
Total loans (b)			53,498			434			3.26			50,963			635			5.00
Mortgage-backed securities			9,785			57			2.39			9,326			58			2.45
Other investment securities			2,857			17			2.47			2,765			17			2.47
Total investment securities			12,642			74			2.41			12,091			75			2.45
Interest-bearing deposits with banks			9,709			2			0.11			2,694			16			2.37
Other short-term investments			140			1			0.48			142			1			1.34
Total earning assets			75,989			511			2.71			65,890			727			4.42
Cash and due from banks			848									900
Allowance for loan losses			(932)									(660)
Accrued income and other assets			5,739									5,122
Total assets			$	81,644								$	71,252
Money market and interest-bearing checking deposits			$	26,320		12			0.18			$	22,913		53			0.93
Savings deposits			2,394			—			0.02			2,169			—			0.03
Customer certificates of deposit			2,801			8			1.21			2,346			7			1.10
Other time deposits			—			—			—			1,156			7			2.46
Foreign office time deposits			81			—			0.34			13			—			1.54
Total interest-bearing deposits			31,596			20			0.26			28,597			67			0.94
Short-term borrowings			882			1			0.25			927			6			2.46
Medium- and long-term debt			7,206			19			1.09			6,712			51			3.05
Total interest-bearing sources			39,684			40			0.41			36,236			124			1.37
Noninterest-bearing deposits			32,686									26,398
Accrued expenses and other liabilities			1,682									1,333
Total shareholders’ equity			7,592									7,285
Total liabilities and shareholders’ equity			$	81,644								$	71,252
Net interest income/rate spread						$	471		2.30						$	603		3.05
Impact of net noninterest-bearing sources of funds									0.20									0.61
Net interest margin (as a percentage of average earning assets)									2.50		%							3.66		%

(a)Includes hedge income (losses) of $19 million and $(1) million for the three months ended June 30, 2020 and June 30, 2019, respectively.

(b)Nonaccrual loans are included in average balances reported and in the calculation of average rates.

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Rate/Volume Analysis

			Three Months Ended
			June 30, 2020/June 30, 2019
(in millions)			Decrease Due to Rate						Increase Due to Volume (a)						Net Decrease
Interest Income:
Loans			$	(221)					$	20					$	(201)
Investment securities			(2)						1						(1)
Interest-bearing deposits with banks			(16)						2						(14)
Total interest income			(239)						23						(216)
Interest Expense:
Interest-bearing deposits			(49)						2						(47)
Short-term borrowings			(5)						—						(5)
Medium- and long-term debt			(34)						2						(32)
Total interest expense			(88)						4						(84)
Net interest income			$	(151)					$	19					$	(132)

(a)Rate/volume variances are allocated to variances due to volume.

Net interest income was $471 million for the three months ended June 30, 2020, a decrease of $132 million compared to $603 million for the three months ended June 30, 2019. The decrease in net interest income primarily reflected the impact of lower short-term rates partially offset by the impact of a $2.5 billion increase in average loans, primarily PPP loans. The decline in rates led to the 116 basis point decrease in the net interest margin, to 2.50 percent for the three months ended June 30, 2020 from 3.66 percent for the three months ended June 30, 2019.

Provision for Credit Losses

        The provision for credit losses, which includes the provision for loan losses and the provision for credit losses on lending-related commitments, was $138 million for the three months ended June 30, 2020, compared to $44 million for the three months ended June 30, 2019. The provision for credit losses for the three months ended June 30, 2020, which was calculated under the CECL model, increased primarily due to the forecasted impact of the COVID-19 pandemic, including the economic impacts of social distancing, and sustained pressures on the Energy portfolio. Net loan charge-offs increased $17 million to $50 million, or 0.37 percent of average total loans for the three months ended June 30, 2020, compared to $33 million, or 0.26 percent of average total loans for the three months ended June 30, 2019. The increase was driven by a $20 million increase in net charge-offs of Energy loans.

        An analysis of the allowance for credit losses and a summary of nonperforming assets are presented under the "Credit Risk" subheading in the "Risk Management" section of this financial review. Further information about the adoption of CECL, which resulted in a $17 million decrease to the allowance for credit losses as of January 1, 2020, is presented in Note 1 to the consolidated financial statements.

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Noninterest Income

			Three Months Ended June 30,
(in millions)			2020						2019
Card fees			$	68					$	65
Fiduciary income			52						52
Service charges on deposit accounts			42						51
Commercial lending fees			17						21
Foreign exchange income			9						11
Bank-owned life insurance			9						11
Letter of credit fees			9						10
Brokerage fees			5						7
Net securities gains			1						—
Other noninterest income (a)			35						22
Total noninterest income			$	247					$	250

(a)The table below provides further details on certain categories included in other noninterest income.

        Noninterest income decreased $3 million to $247 million for the three months ended June 30, 2020, including a reduction in service charges on deposit accounts reflecting the impacts of social distancing, syndication agent fees (a component of commercial lending fees) and smaller decreases in other categories, partially offset by higher securities trading income and customer derivative income (both included in other noninterest income and detailed below), as well as an increase in card fees.

        The following table presents certain categories included in other noninterest income on the Consolidated Statements of Comprehensive Income.

			Three Months Ended June 30,
(in millions)			2020						2019
Customer derivative income			$	10					$	6
Securities trading income			10						2
Investment banking fees			4						1
Deferred compensation asset returns (a)			2						—
Income from principal investing and warrants			—						2
All other noninterest income			9						11
Other noninterest income			$	35					$	22

(a) Compensation deferred by the Corporation's officers and directors is invested based on investment selections of the officers and directors. Income earned on these assets is reported in other noninterest income and the offsetting change in deferred compensation plan liabilities is reported in salaries and benefits expense.

Noninterest Expenses

			Three Months Ended June 30,
(in millions)			2020						2019
Salaries and benefits expense			$	249					$	245
Outside processing fee expense (a)			62						65
Occupancy expense			37						37
Software expense (a)			39						28
Equipment expense			12						12
Advertising expense			8						9
FDIC insurance expense			8						6
Other noninterest expenses			25						22
Total noninterest expenses			$	440					$	424

(a) Amounts reported for the three months ended June 30, 2020 included an $8 million classification adjustment for costs incurred in cloud computing arrangements, reducing outside processing fee expense and increasing software expense due to the prospective adoption of ASU No. 2018-15, effective January 1, 2020.

Noninterest expenses increased $16 million to $440 million. Excluding the $8 million classification adjustment for the prospective adoption of ASU No. 2018-15, the increase in noninterest expenses primarily reflected higher outside processing fee expense, salaries and benefits expense and software expense. The increase in salaries and benefits expense was driven by annual merit increases and the payment of COVID-19-related stipends, partially offset by lower technology-related labor costs.

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Six Months Ended June 30, 2020 compared to Six Months Ended June 30, 2019

Analysis of Net Interest Income

			Six Months Ended
			June 30, 2020																		June 30, 2019
(dollar amounts in millions)			Average Balance			Interest			Average Rate						Average Balance			Interest			Average Rate
Commercial loans (a)			$	32,321		$	585		3.64		%				$	32,037		$	799		5.03		%
Real estate construction loans			3,725			78			4.19						3,279			93			5.74
Commercial mortgage loans			9,719			177			3.66						9,028			230			5.13
Lease financing			587			10			3.49						533			8			3.08
International loans			1,071			21			3.96						1,019			27			5.33
Residential mortgage loans			1,875			34			3.58						1,954			38			3.89
Consumer loans			2,253			46			4.12						2,473			61			5.00
Total loans (b)			51,551			951			3.71						50,323			1,256			5.03
Mortgage-backed securities			9,649			114			2.40						9,275			114			2.43
Other investment securities			2,837			34			2.47						2,748			33			2.40
Total investment securities			12,486			148			2.42						12,023			147			2.42
Interest-bearing deposits with banks			7,558			20			0.55						2,773			33			2.38
Other short-term investments			147			1			0.80						138			1			1.34
Total earning assets			71,742			1,120			3.15						65,257			1,437			4.43
Cash and due from banks			843												912
Allowance for loan losses			(812)												(666)
Accrued income and other assets			5,681												5,012
Total assets			$	77,454											$	70,515
Money market and interest-bearing checking deposits			$	25,486		57			0.45						$	22,763		100			0.88
Savings deposits			2,298			—			0.04						2,169			—			0.04
Customer certificates of deposit			2,900			19			1.32						2,258			11			0.96
Other time deposits			35			—			2.00						661			8			2.45
Foreign office time deposits			82			—			0.82						13			—			1.54
Total interest-bearing deposits			30,801			76			0.50						27,864			119			0.86
Short-term borrowings			519			1			0.34						576			7			2.45
Medium- and long-term debt			7,266			59			1.63						6,703			102			3.07
Total interest-bearing sources			38,586			136			0.71						35,143			228			1.30
Noninterest-bearing deposits			29,723												26,634
Accrued expenses and other liabilities			1,630												1,367
Total shareholders’ equity			7,515												7,371
Total liabilities and shareholders’ equity			$	77,454											$	70,515
Net interest income/rate spread						$	984		2.44									$	1,209		3.13
Impact of net noninterest-bearing sources of funds									0.33												0.60
Net interest margin (as a percentage of average earning assets)									2.77		%										3.73		%

(a) Includes hedge income (losses) of $22 million and $(1) million for the six months ended June 30, 2020 and 2019, respectively.

(b)Nonaccrual loans are included in average balances reported and in the calculation of average rates.

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Rate/Volume Analysis

			Six Months Ended
			June 30, 2020/June 30, 2019
(in millions)			Decrease Due to Rate						Increase Due to Volume (a)						Net (Decrease) Increase
Interest Income:
Loans			$	(329)					$	24					$	(305)
Investment securities			—						1						1
Interest-bearing deposits with banks			(26)						13						(13)
Total interest income			(355)						38						(317)
Interest Expense:
Interest-bearing deposits			(47)						4						(43)
Short-term borrowings			(6)						—						(6)
Medium- and long-term debt			(46)						3						(43)
Total interest expense			(99)						7						(92)
Net interest income			$	(256)					$	31					$	(225)

(a)Rate/volume variances are allocated to variances due to volume.

Net interest income was $984 million for the six months ended June 30, 2020, a decrease of $225 million compared to $1.2 billion for the six months ended June 30, 2019. Net interest margin was 2.77 percent for the six months ended June 30, 2020, a decrease of 96 basis points compared to 3.73 percent for the comparable period in 2019. The decrease in net interest income and margin reflected the impact of lower short-term rates partially offset by the impact of a $1.2 billion increase in average loans, primarily from PPP loans.

For further discussion of the effects of market rates on net interest income, refer to the "Market and Liquidity Risk" section of this financial review.

Provision for Credit Losses

The provision for credit losses, which includes both the provision for loan losses and the provision for credit losses on lending-related commitments, was $549 million for the six months ended June 30, 2020, compared to $31 million for the six months ended June 30, 2019. The provision for credit losses for the six months ended June 30, 2020, which was calculated under the CECL model, increased primarily due to the forecasted impact of the COVID-19 pandemic, including the economic impacts of social distancing, and sustained pressures on the Energy portfolio. Net loan charge-offs increased $90 million to $134 million for the six months ended June 30, 2020, compared to $44 million for the six months ended June 30, 2019, driven by a $79 million increase in net charge-offs of Energy loans.

An analysis of the allowance for credit losses and nonperforming assets is presented under the "Credit Risk" subheading in the "Risk Management" section of this financial review.

Noninterest Income

			Six Months Ended June 30,
(in millions)			2020						2019
Card fees			$	127					$	128
Fiduciary income			106						101
Service charges on deposit accounts			91						102
Commercial lending fees			34						43
Foreign exchange income			20						22
Bank-owned life insurance			21						20
Letter of credit fees			18						19
Brokerage fees			12						14
Net securities losses			—						(8)
Other noninterest income (a)			55						47
Total noninterest income			$	484					$	488

(a)The table below provides further details on certain categories included in other noninterest income.

        Noninterest income decreased $4 million to $484 million, including a reduction in service charges on deposit accounts and syndication agent fees (included in commercial lending fees), as well as smaller decreases in other categories. These declines were partially offset by higher fiduciary income as well as increases included in other noninterest income and detailed

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below, primarily in securities trading income, customer derivative income, investment banking fees, and the impact of losses related to securities repositioning during the six-month period ended June 30, 2019.

        The following table presents certain categories included in other noninterest income on the Consolidated Statements of Comprehensive Income.

			Six Months Ended June 30,
(in millions)			2020						2019
Customer derivative income (a)			$	19					$	13
Securities trading income			12						4
Investment banking fees			7						3
Income from principal investing and warrants			—						3
Deferred compensation asset returns (b)			(1)						2
All other noninterest income			18						22
Other noninterest income			$	55					$	47

(a)Customer derivative income included unfavorable valuation adjustments of $16 million and $5 million for the six months ended June 30, 2020 and 2019, respectively.

(b) Compensation deferred by the Corporation's officers and directors is invested based on investment selections of the officers and directors. Income earned on these assets is reported in other noninterest income and the offsetting change in deferred compensation plan liabilities is reported in salaries and benefits expense.

Noninterest Expenses

			Six Months Ended June 30,
(in millions)			2020						2019
Salaries and benefits expense			$	491					$	510
Outside processing fee expense (a)			119						128
Occupancy expense			74						74
Software expense (a)			76						57
Equipment expense			24						24
Advertising expense			15						14
FDIC insurance expense			16						11
Other noninterest expenses			50						39
Total noninterest expenses			$	865					$	857

(a) Amounts reported for the six months ended June 30, 2020 included a $15 million classification adjustment for costs incurred in cloud computing arrangements, reducing outside processing fee expense and increasing software expense due to the prospective adoption of ASU No. 2018-15, effective January 1, 2020. 

Noninterest expenses increased $8 million to $865 million. Excluding the $15 million classification adjustment for the prospective adoption of ASU No. 2018-15, the increase in noninterest expenses primarily reflected higher operational losses (included in other noninterest expenses), outside processing fee expense and FDIC insurance expense, partially offset by a decrease in salaries and benefits expense. The decline in salaries and benefits expense included lower incentive and annual stock-based compensation, as well as a reduction in technology-related contingent labor costs, partially offset by annual merit increases and the payment of COVID-19-related stipends.

STRATEGIC LINES OF BUSINESS AND MARKETS

The Corporation has strategically aligned its operations into three major business segments: the Commercial Bank, the Retail Bank and Wealth Management. These business segments are differentiated based on the type of customer and the related products and services provided. In addition to the three major business segments, the Finance Division is also reported as a segment. The Other category includes items not directly associated with these business segments or the Finance segment. The performance of the business segments is not comparable with the Corporation's consolidated results and is not necessarily comparable with similar information for any other financial institution. Additionally, because of the interrelationships of the various segments, the information presented is not indicative of how the segments would perform if they operated as independent entities. Market segment results are also provided for the Corporation's three primary geographic markets: Michigan, California and Texas. In addition to the three primary geographic markets, Other Markets is also reported as a market segment. Note 13 to the consolidated financial statements describes the business activities of each business segment and presents financial results of the business and market segments for the three- and six-month periods ended June 30, 2020 and 2019.

The Corporation's management accounting system assigns balance sheet and income statement items to each segment using certain methodologies, which are regularly reviewed and refined. These methodologies may be modified as the management accounting system is enhanced and changes occur in the organizational structure and/or product lines. Note 22 to

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the consolidated financial statements in the Corporation's 2019 Annual Report describes the Corporation's segment reporting methodology.

Net interest income for each segment reflects the interest income generated by earning assets less interest expense on interest-bearing liabilities plus the net impact from associated internal funds transfer pricing (FTP). The FTP methodology allocates credits to each business segment for deposits and other funds provided as well as charges for loans and other assets being funded. FTP crediting rates for deposits and other funds provided reflect the long-term value of deposits and other funding sources based on their implied maturities. FTP charge rates for funding loans and other assets reflect a matched cost of funds based on the pricing and duration characteristics of the assets. Therefore, net interest income for each segment primarily reflects the volume and associated FTP impacts of loan and deposit levels. As overall interest rates decreased, business segments, particularly those focused on generating deposits, were impacted by lower FTP crediting rates on deposits in the six months ended June 30, 2020 compared to the same period in the prior year. Similarly, FTP charges for funding loans decreased in the six months ended June 30, 2020, compared to the same period in the prior year.

Business Segments

The following sections present a summary of the performance of each of the Corporation's business segments for the six months ended June 30, 2020 compared to the same period in the prior year.

Commercial Bank

			Six Months Ended																								Percent Change
(dollar amounts in millions)			June 30, 2020						June 30, 2019						Change
Earnings summary:
Net interest income			$	782					$	832					$	(50)					(6)		%
Provision for credit losses			513						46						467						n/m
Noninterest income			271						272						(1)						(1)
Noninterest expenses			401						393						8						2
Provision for income taxes			27						153						(126)						(82)
Net income			$	112					$	512					$	(400)					(78)		%
Net credit-related charge-offs			$	131					$	47					$	84					n/m
Selected average balances:
Loans			$	44,253					$	43,241					$	1,012					2		%
Deposits			33,274						28,356						4,918						17

n/m - not meaningful

The $1.0 billion increase in average loans reflected growth in Commercial Real Estate, Mortgage Banker Finance, Corporate Banking and Environmental Services, partially offset by decreases in National Dealer Services and Energy. Average PPP loans totaled $1.0 billion. Average deposits increased $4.9 billion, reflecting increases in all deposit categories due to increased liquidity in the banking system from stimulus programs. The Commercial Bank's net income decreased $400 million to $112 million. Net interest income decreased $50 million to $782 million, due to a $293 million decrease in loan interest income, partially offset by decreases of $220 million in allocated net FTP charges and $23 million in deposit costs. The provision for credit losses increased $467 million to $513 million primarily due to the forecasted impact of the COVID-19 pandemic, including the economic impacts of social distancing and sustained pressures on the Energy portfolio, while net credit-related charge-offs increased $84 million to $131 million, primarily due to Energy net charge-offs of $112 million. Noninterest income was stable, while noninterest expenses increased $8 million, primarily reflecting a $4 million increase in transfer charges as well as higher operational losses, legal fees and outside processing fee expense, partially offset by lower incentive and stock-based compensation.

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Retail Bank

			Six Months Ended																								Percent Change
(dollar amounts in millions)			June 30, 2020						June 30, 2019						Change
Earnings summary:
Net interest income			$	245					$	292					$	(47)					(16)		%
Provision for credit losses			8						(3)						11						n/m
Noninterest income			52						64						(12)						(17)
Noninterest expenses			304						292						12						4
(Benefit) provision for income taxes			(4)						16						(20)						n/m
Net (loss) income			$	(11)					$	51					$	(62)					n/m
Net credit-related charge-offs			$	2					$	—					$	2					n/m
Selected average balances:
Loans			$	2,277					$	2,105					$	172					8		%
Deposits			21,921						20,560						1,361						7

n/m - not meaningful

Average loans increased $172 million due to loans to small businesses, including PPP. Average deposits increased $1.4 billion, reflecting increases in all deposit categories. The Retail Bank's net income decreased $62 million to a net loss of $11 million. Net interest income decreased $47 million to $245 million, due to decreases of $40 million in allocated net FTP credits and $8 million in loan income, partially offset by a $1 million decrease in deposit costs. The provision for credit losses increased $11 million from a benefit of $3 million. Noninterest income decreased $12 million, including a $7 million decrease in service charges on deposit accounts. Noninterest expenses increased $12 million, which included a $7 million increase in operational losses.

Wealth Management

			Six Months Ended																								Percent Change
(dollar amounts in millions)			June 30, 2020						June 30, 2019						Change
Earnings summary:
Net interest income			$	81					$	93					$	(12)					(13)		%
Provision for credit losses			28						(10)						38						n/m
Noninterest income			136						132						4						3
Noninterest expenses			145						139						6						5
Provision for income taxes			9						23						(14)						(59)
Net income			$	35					$	73					$	(38)					(53)		%
Net credit-related charge-offs (recoveries)			$	1					$	(3)					$	4					n/m
Selected average balances:
Loans			$	5,007					$	4,983					$	24					—		%
Deposits			4,120						3,770						350						9

n/m - not meaningful

        Average loans remained relatively stable at $5.0 billion. Average deposits increased $350 million, reflecting increases in all deposit categories. Wealth Management's net income decreased $38 million to $35 million. Net interest income decreased $12 million to $81 million, due to a $27 million decrease in loan income, partially offset by decreases of $12 million in allocated net FTP charges and $3 million in deposit costs. The provision for credit losses increased $38 million from a benefit of $10 million. Noninterest income increased $4 million, primarily due to increased fiduciary income, while noninterest expenses increased $6 million, primarily reflecting increases of $5 million in salaries and benefits expense and $3 million in software expense.

Market Segments

The following sections present a summary of the performance of each of the Corporation's market segments for the six months ended June 30, 2020 compared to the same period in the prior year.

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Michigan

			Six Months Ended																								Percent Change
(dollar amounts in millions)			June 30, 2020						June 30, 2019						Change
Earnings summary:
Net interest income			$	322					$	373					$	(51)					(13)		%
Provision for credit losses			64						(5)						69						n/m
Noninterest income			136						144						(8)						(6)
Noninterest expenses			279						273						6						2
Provision for income taxes			23						56						(33)						(59)
Net income			$	92					$	193					$	(101)					(52)		%
Net credit-related charge-offs			$	3					$	4					$	(1)					(26)		%
Selected average balances:
Loans			$	12,601					$	12,631					$	(30)					—		%
Deposits			22,104						19,854						2,250						11

n/m - not meaningful

Average loans were relatively stable at $12.6 billion and included loans to middle market and small businesses, including PPP loans. Average deposits increased $2.3 billion, reflecting increases in all deposit categories due to increased liquidity in the banking system from stimulus programs. The Michigan market's net income decreased $101 million to $92 million. Net interest income decreased $51 million to $322 million, due to an $84 million decrease in loan income, partially offset by a $27 million increase in allocated net FTP credits and a $6 million decrease in deposit costs. The provision for credit losses increased $69 million from a benefit of $5 million, primarily reflecting increases in general Middle Market and Business Banking. Noninterest income decreased $8 million, including a $5 million decrease in service charges on deposit accounts and a $3 million decline in card fees. Noninterest expenses increased $6 million, including a $3 million increase in operational losses.

California

			Six Months Ended																								Percent Change
(dollar amounts in millions)			June 30, 2020						June 30, 2019						Change
Earnings summary:
Net interest income			$	358					$	411					$	(53)					(13)		%
Provision for credit losses			102						(5)						107						n/m
Noninterest income			72						80						(8)						(10)
Noninterest expenses			201						199						2						1
Provision for income taxes			30						76						(46)						(60)
Net income			$	97					$	221					$	(124)					(56)		%
Net credit-related charge-offs			$	15					$	4					$	11					n/m
Selected average balances:
Loans			$	18,346					$	18,730					$	(384)					(2)		%
Deposits			17,965						16,276						1,689						10

n/m - not meaningful

Average loans decreased $384 million, primarily reflecting a decrease in National Dealer Services. Average deposits increased $1.7 billion, reflecting increases in all deposit categories. The California market's net income decreased $124 million to $97 million. Net interest income decreased $53 million to $358 million, due to a $138 million decrease in loan income, partially offset by decreases of $72 million in allocated net FTP charges and $13 million in deposit costs. The provision for credit losses increased $107 million from a benefit of $5 million, primarily reflecting increases in general Middle Market, Commercial Real Estate and Private Banking. Net credit-related charge-offs increased $11 million to $15 million, primarily reflecting increases in Technology and Life Sciences, Private Banking and general Middle Market. Noninterest income decreased $8 million, including declines in card fees and commercial lending fees, while noninterest expenses were relatively stable.

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Texas

			Six Months Ended																								Percent Change
(dollar amounts in millions)			June 30, 2020						June 30, 2019						Change
Earnings summary:
Net interest income			$	231					$	248					$	(17)					(7)		%
Provision for credit losses			321						38						283						n/m
Noninterest income			60						66						(6)						(8)
Noninterest expenses			175						169						6						4
(Benefit) provision for income taxes			(46)						25						(71)						n/m
Net (loss) income			$	(159)					$	82					$	(241)					n/m
Net credit-related charge-offs			$	116					$	39					$	77					n/m
Selected average balances:
Loans			$	10,870					$	10,474					$	396					4		%
Deposits			9,705						8,682						1,023						12

n/m - not meaningful

Average loans increased $396 million, primarily reflecting increases in Commercial Real Estate and Corporate Banking, partially offset by decreases in Energy and National Dealer Services. Average deposits increased $1.0 billion, reflecting increases in all deposit categories. The Texas market's net income decreased $241 million to a net loss of $159 million. Net interest income decreased $17 million to $231 million, due to a $67 million decrease in loan income, partially offset by decreases of $48 million in allocated net FTP charges and $2 million in deposit costs. The provision for credit losses increased $283 million, primarily reflecting an increase in Energy, while net credit-related charge-offs included $112 million in Energy net charge-offs. Noninterest income decreased $6 million, primarily reflecting lower service charges on deposit accounts and commercial lending fees. Noninterest expenses increased $6 million, primarily due to increases of $3 million in transfer charges and $2 million in operational losses.

Other Markets

			Six Months Ended																								Percent Change
(dollar amounts in millions)			June 30, 2020						June 30, 2019						Change
Earnings summary:
Net interest income			$	197					$	185					$	12					6		%
Provision for credit losses			62						5						57						n/m
Noninterest income			191						178						13						7
Noninterest expenses			195						183						12						7
Provision for income taxes			25						35						(10)						(28)
Net income			$	106					$	140					$	(34)					(24)		%
Net credit-related recoveries			$	—					$	(3)					$	3					n/m
Selected average balances:
Loans			$	9,735					$	8,494					$	1,241					15		%
Deposits			9,541						7,874						1,667						21

n/m - not meaningful

Average loans increased $1.2 billion, primarily reflecting increases in general Middle Market and Mortgage Banker Finance, partially offset by a decrease in National Dealer Services. Average deposits increased $1.7 billion, including increases in noninterest-bearing and relationship-based interest-bearing deposits. Other Markets' net income decreased $34 million to $106 million. Net interest income increased $12 million to $197 million due to decreases of $46 million in allocated net FTP charges and $6 million in deposit costs, partially offset by a $40 million decrease in loan income. The provision for credit losses increased $57 million to $62 million, primarily reflecting increases in Corporate Banking and Environmental Services. Noninterest income increased $13 million, including $5 million increases in securities trading income and card fees as well as higher fiduciary income. Noninterest expenses increased $12 million, primarily reflecting increases of $6 million in operational losses and $4 million in software expense.

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Finance & Other

			Six Months Ended																								Percent Change
(dollar amounts in millions)			June 30, 2020						June 30, 2019						Change
Earnings summary:
Net interest income			$	(124)					$	(8)					$	(116)					n/m
Provision for credit losses			—						(2)						2						n/m
Noninterest income			25						20						5						25
Noninterest expenses			15						33						(18)						(54)
Benefit for income taxes			(26)						(20)						(6)						31
Net (loss) income			$	(88)					$	1					$	(89)					n/m
Selected average balances:
Loans			$	(1)					$	(6)					$	5					(73)		%
Deposits			1,209						1,812						(603)						(33)

n/m - not meaningful

Average deposits decreased $603 million, primarily reflecting a decrease in other time deposits. Net income for the Finance & Other category decreased $89 million to a net loss of $88 million, from net income of $1 million. Net interest income decreased $116 million, primarily reflecting a decrease in net FTP revenue as a result of lower rates charged to the business segments under the Corporation's internal FTP methodology and higher levels of wholesale funding. Noninterest expenses decreased $18 million, driven by lower salaries and benefits expense.

The following table lists the Corporation's banking centers by geographic market segment.

			June 30,
			2020						2019
Michigan			190						192
Texas			123						123
California			96						96
Other Markets			25						25
Total			434						436

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FINANCIAL CONDITION

Second Quarter 2020 Compared to Fourth Quarter 2019

Period-End Balances

Total assets increased $11.0 billion to $84.4 billion, primarily due to increases of $7.4 billion in interest-bearing deposits with banks and $3.1 billion in loans. The growth in interest-bearing deposits with banks (primarily deposits with the Federal Reserve Bank) resulted from increased liquidity in the banking system from stimulus programs. The increase in loans reflected growth in Mortgage Banker Finance due to seasonality and elevated refinancing activity as well as increases in Business Banking, Commercial Real Estate, general Middle Market, Retail Banking (small businesses) and Corporate Banking, partially offset by decreases in National Dealer Services and Equity Fund Services. At June 30, 2020, PPP loans totaled $3.8 billion, driving the growth in general Middle Market, Business Banking and Retail Banking (small businesses).

Total liabilities increased $10.5 billion to $76.6 billion, reflecting increases of $8.2 billion and $2.2 billion in noninterest-bearing and interest-bearing deposits, respectively, as customers conserved liquidity as described in the asset discussion above. Total shareholders' equity increased $475 million, including net proceeds of $395 million from the issuance of preferred stock in May 2020.

Average Balances

Total assets increased $8.5 billion to $81.6 billion, primarily due to increases of $4.9 billion in interest-bearing deposits with banks and $3.0 billion in loans. The following table provides information about the change in the Corporation's average loan portfolio by loan type and geographic market.

			Three Months Ended																								Percent Change
(average balances; dollar amounts in millions)			June 30, 2020						December 31, 2019						Change
By Loan Type:
Commercial loans (a)			$	33,944					$	31,808					$	2,136					7		%
Real estate construction loans			3,887						3,398						489						14
Commercial mortgage loans			9,800						9,356						444						5
Lease financing			592						586						6						1
International loans			1,137						1,030						107						10
Residential mortgage loans			1,895						1,887						8						—
Consumer loans			2,243						2,440						(197)						(8)
Total loans			$	53,498					$	50,505					$	2,993					6		%
Loans By Geographic Market:
Michigan			$	13,014					$	12,399					$	615					5		%
California			18,663						17,943						720						4
Texas			11,184						10,708						476						4
Other Markets and Finance			10,637						9,455						1,182						13
Total loans			$	53,498					$	50,505					$	2,993					6		%

(a)Includes PPP loans of $2.6 billion for the three months ended June 30, 2020.

The increase in loans reflected growth in Corporate Banking, Commercial Real Estate, general Middle Market, Mortgage Banker Finance (due to seasonality and elevated refinancing activity) and Business Banking, partially offset by a decrease in National Dealer Services and Energy. The average balance of PPP loans for the three months ended June 30, 2020 was $2.6 billion, driving the growth in general Middle Market and Business Banking.

Total liabilities increased $8.1 billion to $74.1 billion, reflecting increases of $5.7 billion and $1.4 billion in noninterest-bearing and interest-bearing deposits, respectively. Total shareholders' equity increased $355 million to $7.6 billion, resulting primarily from the same reasons as described in the period-end discussion above.

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Capital

The following table presents a summary of changes in total shareholders' equity for the six months ended June 30, 2020.

(in millions)
Balance at January 1, 2020									$	7,327
Cumulative effect of change in accounting principle (a)									13
Net income									48
Cash dividends declared on common stock									(192)
Purchase of common stock									(194)
Issuance of preferred stock									395
Other comprehensive income:
Investment securities			$	218
Cash flow hedges			162
Defined benefit and other postretirement plans			13
Total other comprehensive income									393
Share-based compensation									12
Balance at June 30, 2020									$	7,802

(a)Effective January 1, 2020, the Corporation adopted the provisions of ASU No. 2016-13, "Financial Instruments - Credit Losses" (Topic 326). For further information, refer to Note 1 to the consolidated financial statements.

The following table summarizes the Corporation's repurchase activity during the six months ended June 30, 2020.

(shares in thousands)			Total Number of Shares Purchased as  Part of Publicly Announced Repurchase Plans or Programs						Remaining Share Repurchase Authorization (a)						Total Number of Shares Purchased (b)						Average Price Paid Per  Share
Total first quarter 2020			3,227						4,870						3,322						$	58.70
April 2020			—						4,870						6						28.63
May 2020			—						4,870						—						—
June 2020			—						4,870						—						—
Total second quarter 2020			—						4,870						6						28.62
Total 2020 year-to-date			3,227						4,870						3,328						58.65

(a)Maximum number of shares that may yet be purchased under the publicly announced plans or programs.

(b)Includes approximately 101,000 shares purchased pursuant to deferred compensation plans and shares purchased from employees to pay for taxes related to restricted stock vesting under the terms of an employee share-based compensation plan during the six months ended June 30, 2020. These transactions are not considered part of the Corporation's repurchase program.

In March 2020, the Corporation suspended its share repurchase program, with a focus on deploying capital to meet customers' growing financing requirements, resulting in no share repurchases under the program during second quarter 2020. The Corporation will continue to assess the resumption of repurchases subject to various factors including financial performance, capital needs and market conditions. Since its inception in 2010, a total of 87.2 million shares have been authorized for repurchase. There is no expiration date for the share repurchase program.

In May 2020, the Corporation issued $400 million of 5.625% non-cumulative perpetual preferred stock, which yielded $395 million in proceeds net of underwriting discounts and offering expenses. See Note 9 to the consolidated financial statements for further information about the terms of the preferred stock.

        The Corporation is prepared to continue using capital and liquidity in a responsible way to assist customers impacted by the COVID-19 crisis with a target of attaining and maintaining a Common Equity Tier 1 (CET1) capital ratio of approximately 10 percent. At June 30, 2020, the Corporation's estimated CET1 capital ratio was 9.97 percent, a decrease of 16 thousand basis points compared to December 31, 2019. In 2020, the Corporation elected regulatory relief to defer the impact of adopting the CECL model for measuring credit losses on regulatory capital, which resulted in a cumulative 13-basis-point benefit to the estimated CET1 capital ratio at June 30, 2020. Also in 2020, the Corporation adopted capital rules issued by federal banking agencies that simplified certain regulatory capital rules, including the capital treatment of mortgage servicing assets, certain deferred tax assets, investments in the capital instruments of unconsolidated financial institutions and minority interests.

        The following table presents the minimum ratios required.

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Common equity tier 1 capital to risk-weighted assets			4.5		%
Tier 1 capital to risk-weighted assets			6.0
Total capital to risk-weighted assets			8.0
Capital conservation buffer (a)			2.5
Tier 1 capital to adjusted average assets (leverage ratio)			4.0

(a)In addition to the minimum risk-based capital requirements, the Corporation is required to maintain a minimum capital conservation buffer, in the form of common equity, in order to avoid restrictions on capital distributions and discretionary bonuses.

The Corporation's capital ratios exceeded minimum regulatory requirements as follows:

			June 30, 2020																		December 31, 2019
(dollar amounts in millions)			Capital/Assets						Ratio						Capital/Assets						Ratio
Common equity tier 1 (a), (b)			$	6,698					9.97		%				$	6,919					10.13		%
Tier 1 risk-based (a), (b)			7,093						10.56						6,919						10.13
Total risk-based (a)			8,686						12.93						8,282						12.13
Leverage (a)			7,093						8.76						6,919						9.51
Common equity			7,407						8.78						7,327						9.98
Tangible common equity (b)			6,769						8.08						6,688						9.19
Risk-weighted assets (a)			67,156												68,273

(a) June 30, 2020 capital, risk-weighted assets and ratios are estimated and reflect deferral of CECL model impact as calculated per regulatory guidance.

(b) See Supplemental Financial Data section for reconciliations of non-GAAP financial measures and regulatory ratios.

RISK MANAGEMENT

The following updated information should be read in conjunction with the "Risk Management" section on pages F-20 through F-33 in the Corporation's 2019 Annual Report.

Credit Risk

Allowance for Credit Losses

The allowance for credit losses includes both the allowance for loan losses and the allowance for credit losses on lending-related commitments. Effective January 1, 2020, the allowance for credit losses reflected the adoption of Topic 326, which requires companies to estimate credit losses using the CECL framework. As a percentage of total loans, the allowance for credit losses was 1.99 percent at June 30, 2020, compared to 1.33 percent at December 31, 2019. Excluding $3.8 billion in PPP loans, which are guaranteed by the Small Business Administration, the allowance for credit losses was 2.15 percent of total loans at June 30, 2020. The allowance for credit losses covered 3.9 times and 3.3 times total nonperforming loans at June 30, 2020 and December 31, 2019, respectively.

At adoption on January 1, 2020, the scope and severity of the economic crisis resulting from the eventual COVID-19 pandemic were unknown. As such, the economic scenario used by the Corporation to develop its estimate of CECL as of the adoption date reflected a continued moderate U.S. economic expansion compared to 2019 levels and a stable interest rate environment, with the federal funds rate remaining in the 1.50- to 1.75-percent range. Other assumptions included resolution of trade tensions, a calmer global economy and a strong U.S. dollar, all of which supported modest industrial production growth and stable oil prices. The economic scenario also assumed strong labor market conditions to support the consumer sector. Management also considered the level of uncertainty regarding its economic assumptions as part of the qualitative adjustment. The adoption of CECL resulted in a $17 million day-one decrease in the allowance for credit losses, from $668 million at December 31, 2019 under the incurred loss model. See Note 1 to the consolidated financial statements for further information about the adoption of CECL.

The allowance for credit losses increased by $415 million from adoption date to $1.1 billion at June 30, 2020, primarily reflecting the economic impacts of the COVID-19 pandemic and the response by domestic and global governmental authorities, including quarantines and other social distancing policies aimed at fighting the spread of the virus. Energy markets, which were experiencing already reduced capital market activity prior to the pandemic, showed continued stress through the first half of 2020. The U.S. economy contracted into a recession with unusual speed and force, ending the longest expansionary period in U.S. history. The U.S. government and the Federal Reserve responded to the pandemic with unprecedented measures. In addition to the Federal Reserve reducing the target federal funds rate to zero to 0.25 percent, Congress passed the Coronavirus Aid, Relief, and Economic Security Act (CARES Act) that included an estimated $2 trillion stimulus package. During second quarter 2020, states across the U.S. began loosening social distancing policies, stimulating economic activity. While economic conditions showed signs of improvement toward the end of the second quarter 2020, there continues to be uncertainty regarding the impact to the U.S. economy from a secondary wave of COVID-19 cases as jurisdictions begin to reopen across the country and the mitigating impacts of government intervention. These developments shaped the 2-year

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reasonable and supportable forecast used by the Corporation in its calculation of the CECL estimate at June 30, 2020. After a sharp decline in GDP in second quarter 2020, the forecast reflects growth through the end of 2020, normalizing to historical growth rates by the end of the forecast period. Forecasts for other key economic variables, including the unemployment rate, oil prices and industrial production levels, are generally in line with GDP projections. Interest rates remain low, reflecting the Federal Reserve's expectation that rates will remain at current levels in the near-to mid-term, while corporate bond rates reflect decreasing default risk as the economy recovers. The following table summarizes the forecasts for the economic variables most impactful to the allowance for credit losses estimate at June 30, 2020.

Economic Variable			Base Forecast
Real GDP growth			Grows by 24 percent in third quarter 2020, normalizing into a long-term growth rate of 2 percent by the end of the forecast period.
Unemployment rate			Remaining above 10 percent through third quarter 2020, gradually decreasing to 7 percent by the end of the forecast period.
Corporate BBB bond to 10-year Treasury bond spreads			Third quarter 2020 spread of 3 percent reflects residual impacts of economic uncertainty, followed by a sharp, short-term decline then normalizing to a rate of 2 percent by the end of the forecast period.
Oil Prices			Prices below $30 per barrel in third quarter, increase in line with GDP through the forecast period, stabilizing at $50 per barrel by first quarter 2022.

Due to the high degree of uncertainty regarding the ultimate economic consequences of the pandemic, as well as the effectiveness of the government's stimulus packages, management also considered other economic scenarios to make appropriate qualitative adjustments for certain sectors of its lending portfolio, including more benign and more severe forecasts.

Allowance for Loan Losses

The allowance for loan losses represents management’s estimates of current expected credit losses in the Corporation’s loan portfolio. Pools of loans with similar risk characteristics are collectively evaluated, while loans that no longer share risk characteristics with loan pools are evaluated individually.

Collective loss estimates are determined by applying reserve factors, designed to estimate current expected credit losses, to amortized cost balances over the remaining contractual life of the collectively evaluated portfolio. Loans with similar risk characteristics are aggregated into homogeneous pools. The allowance for loan losses also includes qualitative adjustments to bring the allowance to the level management believes is appropriate based on factors that have not otherwise been fully accounted for, including adjustments for foresight risk, input imprecisions and model imprecision. Credit losses for loans that no longer share risk characteristics with the loan pools are estimated on an individual basis. Individual credit loss estimates are typically performed for nonaccrual loans and modified loans classified as TDRs and are based on one of several methods, including the estimated fair value of the underlying collateral, observable market value of similar debt or the present value of expected cash flows. 

As a percentage of total loans, the allowance for loan losses was 1.88 percent at June 30, 2020, compared to 1.27 percent at December 31, 2019. Excluding PPP loans, the allowance for loan losses was 2.03 percent of total loans at June 30, 2020. The allocation of reserves for Energy loans remains above 10 percent in response to sustained pressures on the Energy portfolio. Nonperforming loans were 0.51 percent of total loans at June 30, 2020, compared to 0.40 percent at December 31, 2019, and the allowance covered 3.7 times and 3.1 times total nonperforming loans at June 30, 2020 and December 31, 2019, respectively.

Allowance for Credit Losses on Lending-Related Commitments

        The allowance for credit losses on lending-related commitments estimates current expected credit losses on collective pools of letters of credit and unused commitments to extend credit based on reserve factors, determined in a manner similar to business loans, multiplied by a probability of draw estimate based on historical experience and credit risk, applied to commitment amounts. The allowance for credit losses on lending-related commitments totaled $59 million and $31 million at June 30, 2020 and December 31, 2019, respectively.

        For additional information regarding the allowance for credit losses, refer to the "Critical Accounting Policies" section and Note 1 to the consolidated financial statements.

Nonperforming Assets

Nonperforming assets include loans on nonaccrual status, TDRs which have been renegotiated to less than the original contractual rates (reduced-rate loans) and foreclosed property. TDRs include performing and nonperforming loans, with nonperforming TDRs on either nonaccrual or reduced-rate status. Certain provisions within the CARES Act encourage financial institutions to practice prudent efforts to work with borrowers impacted by COVID-19. Under these provisions, modifications

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deemed to be COVID-19-related would not be considered a TDR if the loan was not more than 30 days past due as of December 31, 2019 and the deferral was executed between March 1, 2020 and the earlier of 60 days after the date of termination of the COVID-19 national emergency or December 31, 2020. The banking regulators issued similar guidance, which also clarified that a COVID-19-related modification should not be considered a TDR if the borrower was current on payments at the time the underlying loan modification program was implemented and if the modification was considered to be short-term. Modifications are first evaluated for eligibility under the CARES Act, then the interagency guidance if they do not qualify for the CARES Act relief. Modifications that are not eligible for either program continue to follow the Corporation’s established TDR policy. For loans not otherwise reportable as past due or nonaccrual, financial institutions are generally not expected to designate loans with deferrals granted due to COVID-19 as past due or nonaccrual. As of June 30, 2020, the Corporation granted payment deferrals for approximately 2,100 obligors with an aggregate loan balance of $4.5 billion, which primarily consisted of commercial loans, including $57 million of loans on their second deferral.

The following table presents a summary of nonperforming assets and past due loans.

(dollar amounts in millions)			June 30, 2020						December 31, 2019
Nonaccrual loans:
Business loans:
Commercial			$	200					$	148
Commercial mortgage			21						14
Lease financing			1						—
Total nonaccrual business loans			222						162
Retail loans:
Residential mortgage			24						20
Consumer:
Home equity			21						17
Total nonaccrual retail loans			45						37
Total nonaccrual loans			267						199
Reduced-rate loans			4						5
Total nonperforming loans			271						204
Foreclosed property			11						11
Total nonperforming assets			$	282					$	215
Nonperforming loans as a percentage of total loans			0.51		%				0.40		%
Nonperforming assets as a percentage of total loans and foreclosed property			0.53						0.43
Allowance for credit losses as a multiple of total nonperforming loans			3.9x						3.3x
Loans past due 90 days or more and still accruing			$	41					$	26

Nonperforming assets increased $67 million to $282 million at June 30, 2020, from $215 million at December 31, 2019. The increase in nonperforming assets primarily reflected a $59 million increase in nonperforming Energy loans, which are a component of commercial loans.

The following table presents a summary of TDRs at June 30, 2020 and December 31, 2019. The table does not include loan modifications related to the COVID-19 pandemic.

(in millions)			June 30, 2020						December 31, 2019
Nonperforming TDRs:
Nonaccrual TDRs			$	46					$	36
Reduced-rate TDRs			4						5
Total nonperforming TDRs			50						41
Performing TDRs (a)			40						69
Total TDRs			$	90					$	110

(a)TDRs that do not include a reduction in the original contractual interest rate which are performing in accordance with their modified terms.

During the six months ended June 30, 2020, $22 million of previously performing Energy TDRs were transferred to nonaccrual or charged off. At June 30, 2020, Energy TDRs totaled $23 million, all of which were on nonaccrual status, compared to $14 million at December 31, 2019.

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The following table presents a summary of changes in nonaccrual loans.

			Three Months Ended
(in millions)			June 30, 2020						March 31, 2020						December 31, 2019
Balance at beginning of period			$	235					$	199					$	220
Loans transferred to nonaccrual (a)			96						137						48
Nonaccrual loan gross charge-offs			(57)						(89)						(27)
Loans transferred to accrual status (a)			—						—						(7)
Nonaccrual loans sold			—						—						(10)
Payments/other (b)			(7)						(12)						(25)
Balance at end of period			$	267					$	235					$	199

(a)Based on an analysis of nonaccrual loans with book balances greater than $2 million.

(b)Includes net changes related to nonaccrual loans with balances less than $2 million, payments on nonaccrual loans with book balances greater than $2 million and transfers of nonaccrual loans to foreclosed property.

There were eight borrowers with a balance greater than $2 million, totaling $96 million, transferred to nonaccrual status in second quarter 2020, compared to 13 borrowers, totaling $137 million in first quarter 2020 and six borrowers totaling $48 million in fourth quarter 2019. For further information about the composition of loans transferred to nonaccrual during the current period, refer to the nonaccrual information by industry category table below.

The following table presents the composition of nonaccrual loans by balance and the related number of borrowers at June 30, 2020 and December 31, 2019.

			June 30, 2020																		December 31, 2019
(dollar amounts in millions)			Number of Borrowers						Balance						Number of Borrowers						Balance
Under $2 million			687						$	78					708						$	74
$2 million - $5 million			19						62						8						22
$5 million - $10 million			7						49						6						49
$10 million - $25 million			4						52						4						54
Greater than $25 million			1						26						—						—
Total			718						$	267					726						$	199

The following table presents a summary of nonaccrual loans at June 30, 2020 and loans transferred to nonaccrual and net loan charge-offs (recoveries) for the three months ended June 30, 2020, based primarily on North American Industry Classification System (NAICS) categories.

			June 30, 2020																		Three Months Ended June 30, 2020
(dollar amounts in millions)			Nonaccrual Loans																		Loans Transferred  to Nonaccrual (a)																		Net Loan Charge-Offs (Recoveries)
Industry Category
Mining, Quarrying and Oil & Gas Extraction			$	102					38		%				$	87					91		%				$	45					88		%
Wholesale Trade			41						15						6						6						(1)						(1)
Residential Mortgage			24						9						—						—						—						—
Manufacturing			21						8						—						—						(2)						(3)
Services			13						5						—						—						3						5
Information & Communication			12						5						—						—						—						—
Retail Trade			8						3						—						—						4						9
Real Estate & Home Builders			7						3						3						3						—						—
Health Care & Social Assistance			5						2						—						—						1						2
Contractors			4						1						—						—						—						—
Other (b)			30						11						—						—						—						—
Total			$	267					100		%				$	96					100		%				$	50					100		%

(a)Based on an analysis of nonaccrual loans with book balances greater than $2 million.

(b)Consumer, excluding residential mortgage and certain personal purpose nonaccrual loans and net charge-offs, are included in the Other category.

Loans past due 90 days or more and still accruing interest, which generally are well collateralized and in the process of collection, increased $15 million to $41 million at June 30, 2020, compared to $26 million at December 31, 2019. Loans past due 30-89 days and still accruing interest increased $80 million to $207 million at June 30, 2020, compared to $127 million at December 31, 2019. Loans past due 30 days or more and still accruing interest as a percentage of total loans were 0.46 percent and 0.30 percent at June 30, 2020 and December 31, 2019, respectively. An aging analysis of loans included in Note 4 to the consolidated financial statements provides further information about the balances comprising past due loans.

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The following table presents a summary of total criticized loans. The Corporation's criticized list is consistent with the Special Mention, Substandard and Doubtful categories defined by regulatory authorities. Risk ratings are adjusted as appropriate based on dialogue with borrowers and review of current and projected financial performance, including liquidity and cash flow forecasts as well as receivable and inventory levels. Criticized loans with balances of $2 million or more on nonaccrual status or loans with balances of $1 million or more whose terms have been modified in a TDR are individually subjected to quarterly credit quality reviews, and the Corporation may establish specific allowances for such loans. A table of loans by credit quality indicator included in Note 4 to the consolidated financial statements provides further information about the balances comprising total criticized loans.

(dollar amounts in millions)			June 30, 2020						March 31, 2020						December 31, 2019
Total criticized loans			$	3,379					$	2,457					$	2,120
As a percentage of total loans			6.3		%				4.6		%				4.2		%

The $1.3 billion increase in criticized loans during the six months ended June 30, 2020 included increases of $564 million in general Middle Market and $475 million in Energy.

Concentrations of Credit Risk

Concentrations of credit risk may exist when a number of borrowers are engaged in similar activities, or activities in the same geographic region, and have similar economic characteristics that would cause them to be similarly impacted by changes in economic or other conditions. The Corporation has concentrations of credit risk with the automotive and commercial real estate industries. All other industry concentrations, as defined by management, individually represented less than 10 percent of total loans at June 30, 2020.

Automotive Lending - Dealer:

The following table presents a summary of dealer loans.

			June 30, 2020																		December 31, 2019
(in millions)			Loans Outstanding						Percent of Total Loans						Loans Outstanding						Percent of Total Loans
Dealer:
Floor plan			$	1,971											$	3,967
Other			3,077												3,447
Total dealer			$	5,048					9.4		%				$	7,414					14.7 %

Substantially all dealer loans are in the National Dealer Services business line and primarily include floor plan financing and other loans to automotive dealerships. Floor plan loans, included in commercial loans in the Consolidated Balance Sheets, totaled $2.0 billion at June 30, 2020, a decrease of $2.0 billion compared to $4.0 billion at December 31, 2019 due to lower automotive inventory precipitated by the interruption in automotive production. At June 30, 2020 and December 31, 2019, other loans to automotive dealers in the National Dealer Services business line totaled $3.1 billion and $3.4 billion, respectively, including $2.0 billion of owner-occupied commercial real estate mortgage loans at both June 30, 2020 and December 31, 2019, respectively.

Nonaccrual dealer loans totaled $1 million at June 30, 2020 and $9 million at December 31, 2019. Dealer loan net charge-offs totaled $1 million for the six months ended June 30, 2020, compared to none for the six months ended June 30, 2019.

Automotive Lending- Production:

The following table presents a summary of loans to borrowers involved with automotive production.

			June 30, 2020																		December 31, 2019
(in millions)			Loans Outstanding						Percent of Total Loans						Loans Outstanding						Percent of Total Loans
Production:
Domestic			$	1,040											$	963
Foreign			432												286
Total production			$	1,472					2.8		%				$	1,249					2.5 %

Loans to borrowers involved with automotive production, primarily Tier 1 and Tier 2 suppliers, totaled $1.5 billion and $1.2 billion at June 30, 2020 and December 31, 2019, respectively. These borrowers could face financial difficulties due to disruptions in auto production as well as their supply chains and logistics operations as a result of the COVID-19 pandemic. As such, management prudently continued to increase allocated reserves for this portfolio as of June 30, 2020.

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Nonaccrual loans to borrowers involved with automotive production totaled $9 million at June 30, 2020 and $10 million at December 31, 2019. Criticized automotive production loans were 21 percent of the automotive production portfolio at June 30, 2020, compared to 15 percent at December 31, 2019. Automotive production loan net charge-offs totaled $2 million in the six months ended June 30, 2020, compared to net recoveries of $1 million in the six months ended June 30, 2019.

Commercial Real Estate Lending

The following table summarizes the Corporation's commercial real estate loan portfolio by loan category.

			June 30, 2020																														December 31, 2019
(in millions)			Commercial Real Estate business line (a)						Other (b)						Total						Commercial Real Estate business line (a)						Other (b)						Total
Real estate construction loans			$	3,547					$	405					$	3,952					$	3,044					$	411					$	3,455
Commercial mortgage loans			2,292						7,633						9,925						2,176						7,383						9,559
Total commercial real estate			$	5,839					$	8,038					$	13,877					$	5,220					$	7,794					$	13,014

(a)Primarily loans to real estate developers.

(b)Primarily loans secured by owner-occupied real estate.

The Corporation limits risk inherent in its commercial real estate lending activities by monitoring borrowers directly involved in the commercial real estate markets and adhering to conservative policies on loan-to-value ratios for such loans. Commercial real estate loans, consisting of real estate construction and commercial mortgage loans, totaled $13.9 billion at June 30, 2020, an increase of $863 million compared to December 31, 2019, of which $5.8 billion, or 42 percent, were to borrowers in the Commercial Real Estate business line, including loans to real estate developers. The remaining $8.0 billion, or 58 percent, of commercial real estate loans in other business lines consisted primarily of owner-occupied commercial mortgages, which bear credit characteristics similar to non-commercial real estate business loans.

The real estate construction loan portfolio primarily contains loans made to long-tenured customers with satisfactory completion experience. Criticized real estate construction loans in the Commercial Real Estate business line totaled $17 million and $31 million at June 30, 2020 and December 31, 2019, respectively. In other business lines, there were $14 million criticized real estate construction loans at June 30, 2020, compared to none at December 31, 2019. There were no real estate construction loan charge-offs in either of the six-month periods ended June 30, 2020 and 2019.

Commercial mortgage loans are loans where the primary collateral is a lien on any real property and are primarily loans secured by owner-occupied real estate. Real property is generally considered primary collateral if the value of that collateral represents more than 50 percent of the commitment at loan approval. Loans in the commercial mortgage portfolio generally mature within three to five years. Criticized commercial mortgage loans in the Commercial Real Estate business line totaled $54 million and $55 million at June 30, 2020 and December 31, 2019, respectively. In other business lines, $422 million and $242 million of commercial mortgage loans were criticized at June 30, 2020 and December 31, 2019, respectively. Commercial mortgage loan net recoveries were $2 million for both the six months ended June 30, 2020 and 2019.

Residential Real Estate Lending

Residential real estate loans, which consist of traditional residential mortgages and home equity loans and lines of credit, totaled $3.6 billion, or 7 percent of total loans, at June 30, 2020. The following table summarizes the Corporation's residential mortgage and home equity loan portfolios by geographic market.

			June 30, 2020																																										December 31, 2019
(dollar amounts in millions)			Residential Mortgage Loans						% of Total						Home Equity Loans						% of Total						Residential Mortgage Loans						% of Total						Home Equity Loans						% of Total
Geographic market:
Michigan			$	440					23		%				$	570					34		%				$	412					22		%				$	603					35		%
California			953						51						700						42						932						51						699						41
Texas			260						14						338						20						275						15						346						20
Other Markets			233						12						61						4						226						12						63						4
Total			$	1,886					100		%				$	1,669					100		%				$	1,845					100		%				$	1,711					100		%

The residential real estate portfolio is principally located within the Corporation's primary geographic markets. Substantially all residential real estate loans past due 90 days or more are placed on nonaccrual status, and substantially all junior lien home equity loans that are current or less than 90 days past due are placed on nonaccrual status if full collection of the senior position is in doubt. At no later than 180 days past due, such loans are charged off to current appraised values less costs to sell.

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Residential mortgages totaled $1.9 billion at June 30, 2020, and were primarily larger, variable-rate mortgages originated and retained for certain private banking relationship customers. Of the $1.9 billion of residential mortgage loans outstanding, $24 million were on nonaccrual status at June 30, 2020. The home equity portfolio totaled $1.7 billion at June 30, 2020, of which $1.6 billion was outstanding under primarily variable-rate, interest-only home equity lines of credit, $88 million were in amortizing status and $20 million were closed-end home equity loans. Of the $1.7 billion of home equity loans outstanding, $21 million were on nonaccrual status at June 30, 2020. A majority of the home equity portfolio was secured by junior liens at June 30, 2020. 

Energy Lending

The Corporation has a portfolio of Energy loans included in commercial loans in the Consolidated Balance Sheets. Customers in the Corporation's Energy line of business (approximately 140 relationships) are engaged in three segments of the oil and gas business: exploration and production (E&P), midstream and energy services. E&P generally includes such activities as searching for potential oil and gas fields, drilling exploratory wells and operating active wells. Commitments to E&P borrowers are generally subject to semi-annual borrowing base re-determinations based on a variety of factors including updated pricing (reflecting market and competitive conditions), energy reserve levels and the impact of hedging. The midstream sector is generally involved in the transportation, storage and marketing of crude and/or refined oil and gas products. The Corporation's energy services customers provide products and services primarily to the E&P segment.

The following table summarizes information about loans in the Corporation's Energy business line.

			June 30, 2020																								December 31, 2019
(dollar amounts in millions)			Outstandings									Nonaccrual			Criticized (a)						Outstandings									Nonaccrual			Criticized (a)
Exploration and production (E&P)			$	1,662		80		%	$	102		$	750					$	1,741		78		%	$	43		$	289
Midstream			374			18			—			57						432			20			—			63
Services			50			2			—			34						48			2			—			14
Total Energy business line			$	2,086		100		%	$	102		$	841					$	2,221		100		%	$	43		$	366
As a percentage of total Energy loans															5		%	40		%										2		%	16		%

(a) Includes nonaccrual loans.

Loans in the Energy business line totaled $2.1 billion, or 4 percent of total loans at June 30, 2020, and $2.2 billion at December 31, 2019, a decrease of $135 million. Total exposure, including unused commitments to extend credit and letters of credit, was $3.4 billion and $4.3 billion at June 30, 2020 and December 31, 2019, respectively.

The decrease in total exposure in the Energy business line primarily reflected reduced borrowing bases as a result of lower oil and gas prices. At June 30, 2020, the Corporation had completed approximately 90 percent of the Spring borrowing base re-determinations, resulting in an average reduction to the borrowing bases of 20 percent. Utilization increased to 60 percent primarily as a result of the reduction in exposure at June 30, 2020. The value and coverage benefit of hedging contracts are dependent upon the oil/gas price in each contract, as well as the operational costs, which are different for each borrower. As of June 30, 2020, 73 percent of the Corporation's E&P customers had at least 50 percent of their oil and/or gas production hedged up to one year and 37 percent of customers had at least 50 percent of production hedged for two years or more.

The Corporation's allowance methodology considers the various risk elements within the loan portfolio. When merited, the Corporation may incorporate a qualitative reserve component for Energy loans. The allocation of reserves for Energy loans remained over 10 percent of the Energy portfolio at June 30, 2020 in response to oil market supply/demand imbalances as well as reduced capital market activity. The supply/demand imbalance has been exacerbated by the economic impacts from the COVID-19 pandemic, further stressing the Energy portfolio. Net credit-related Energy charge-offs were $45 million and $112 million for the three- and six-month periods ended June 30, 2020, respectively, compared to $25 million and $33 million for the same periods in 2019. Nonaccrual Energy loans increased $59 million to $102 million at June 30, 2020, compared to December 31, 2019. Criticized Energy loans increased $475 million to $841 million, or 25 percent of total criticized loans, at June 30, 2020.

Leveraged Loans

Certain loans in the Corporation's commercial portfolio are considered leveraged transactions. These loans are typically used for mergers, acquisitions, business recapitalizations, refinancing and equity buyouts. To help mitigate the risk associated with these loans, the Corporation focuses on middle market companies with highly capable management teams, strong sponsors and solid track records of financial performance. Industries prone to cyclical downturns and acquisitions with a high degree of integration risk are generally avoided. Other considerations include the sufficiency of collateral, the level of balance sheet leverage and the adequacy of financial covenants. During the underwriting process, cash flows are stress-tested to evaluate the borrowers' abilities to handle economic downturns and an increase in interest rates. Management considers the leveraged loan portfolio to be one of the most sensitive to economic impacts stemming from the COVID-19 pandemic and

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social distancing policies and has continued to set aside increased reserves for this portfolio as of June 30, 2020. Certain energy, automotive production and loans in other portfolios specifically identified as subject to additional stress due to COVID-19 impacts are also considered leveraged transactions.

The FDIC defines higher-risk commercial and industrial (HR C&I) loans for assessment purposes as loans generally with leverage of four times total debt to earnings before interest, taxes and depreciation (EBITDA) as well as three times senior debt to EBITDA, excluding certain collateralized loans.

The following table summarizes information about HR C&I loans.

(in millions)			June 30, 2020						December 31, 2019
Outstandings			$	2,436					$	2,553
Criticized			440						169
Net loan charge-offs			2020						2019
Three Months Ended June 30,			$	5					$	—
Six Months Ended June 30,			13						5

Other Sectors Most at Risk due to Economic Stress Resulting from COVID-19 Impacts

        The COVID-19 pandemic has negatively impacted the global economy, disrupted global supply chains and increased unemployment levels. The resulting temporary closure of many businesses and the implementation of social distancing and sheltering in place policies may impact many of the Corporation’s customers. In addition to the energy, automotive production and leveraged loan portfolios, the Corporation considers the following sectors of its loan portfolio to be most vulnerable to financial risks from business disruptions caused by the pandemic spread mitigation efforts. For further discussion, see Item 1.A "Risk Factors" on page 65 of this report.

			June 30, 2020
Sector based on NAICS category (dollar amounts in millions)			Loans						Percent of Total Loans						Percent Criticized (a)
Retail Commercial Real Estate (b)			$	784					1.5		%				—		%
Hotels/Casinos			748						1.4						5.4
Arts/Recreation			357						0.7						14.0
Sports Franchises			321						0.6						0.2
Retail Goods and Services			283						0.5						8.2
All other impacted sectors (c)			1,038						1.9						8.2
Total			$	3,531					6.6		%				5.6		%

(a)Sector criticized loans as a percentage of sector total loans.

(b)Loans in the retail commercial real estate sector are primarily included in the Corporation's commercial real estate portfolio.

(c)Includes airlines, restaurants and bars, childcare, coffee shops, cruise lines, education, gasoline and convenience stores, religious organizations, senior living, freight, as well as travel arrangements.

Market and Liquidity Risk

Market risk represents the risk of loss due to adverse movement in prices, including interest rates, foreign exchange rates, commodity prices and equity prices. Liquidity risk represents the risk that the Corporation does not have sufficient access to funds to maintain its normal operations at all times, or does not have the ability to raise or borrow funds at a reasonable cost at all times.

The Asset and Liability Policy Committee (ALCO) of the Corporation establishes and monitors compliance with the policies and risk limits pertaining to market and liquidity risk management activities. ALCO meets regularly to discuss and review market and liquidity risk management strategies and consists of executive and senior management from various areas of the Corporation, including treasury, finance, economics, lending, deposit gathering and risk management. Corporate Treasury mitigates market and liquidity risk under the direction of ALCO through the actions it takes to manage the Corporation's market, liquidity and capital positions.

In addition to assessing liquidity risk on a consolidated basis, Corporate Treasury also monitors the parent company's liquidity and has established limits for the minimum number of months into the future in which the parent company can meet existing and forecasted obligations without the support of additional dividends from subsidiaries. ALCO's liquidity policy requires the parent company to maintain sufficient liquidity to meet expected capital and debt obligations with a target of 24 months but no less than 18 months.

Corporate Treasury and the Enterprise Risk Division support ALCO in measuring, monitoring and managing interest rate risk as well as all other market risks. Key activities encompass: (i) providing information and analyses of the Corporation's

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balance sheet structure and measurement of interest rate and all other market risks; (ii) monitoring and reporting of the Corporation's positions relative to established policy limits and guidelines; (iii) developing and presenting analyses and strategies to adjust risk positions; (iv) reviewing and presenting policies and authorizations for approval; and (v) monitoring of industry trends and analytical tools to be used in the management of interest rate and all other market and liquidity risks.

Interest Rate Risk

Net interest income is the primary source of revenue for the Corporation. Interest rate risk arises in the normal course of business due to differences in the repricing and cash flow characteristics of assets and liabilities, primarily through the Corporation's core business activities of extending loans and acquiring deposits. The Corporation's balance sheet is predominantly characterized by floating-rate loans funded by core deposits. Including the impact of interest rate swaps converting floating-rate loans to fixed, the Corporation's loan composition at June 30, 2020 was 53 percent 30-day LIBOR, 8 percent other LIBOR (primarily 60-and 90-day), 13 percent prime and 26 percent fixed rate. This creates sensitivity to interest rate movements due to the imbalance between the faster repricing of the floating-rate loan portfolio versus deposit products. In addition, the growth and/or contraction in the Corporation's loans and deposits may lead to changes in sensitivity to interest rate movements in the absence of mitigating actions. Examples of such actions are purchasing fixed-rate investment securities, which provide liquidity to the balance sheet and act to mitigate the inherent interest sensitivity, as well as hedging with interest rate swaps and options. Other mitigating factors include interest rate floors on a portion of the loan portfolio. The Corporation actively manages its exposure to interest rate risk with the principal objective of optimizing net interest income and the economic value of equity while operating within acceptable limits established for interest rate risk and maintaining adequate levels of funding and liquidity.

Since no single measurement system satisfies all management objectives, a combination of techniques is used to manage interest rate risk. These techniques examine the impact of interest rate risk on net interest income and the economic value of equity under a variety of alternative scenarios, including changes in the level, slope and shape of the yield curve utilizing multiple simulation analyses. Simulation analyses produce only estimates of net interest income as the assumptions used are inherently uncertain. Actual results may differ from simulated results due to many factors, including, but not limited to, the timing, magnitude and frequency of changes in interest rates, market conditions, regulatory impacts and management strategies.

Sensitivity of Net Interest Income to Changes in Interest Rates

The analysis of the impact of changes in interest rates on net interest income under various interest rate scenarios is management's principal risk management technique. Management models a base-case net interest income under an unchanged interest rate environment. Existing derivative instruments entered into for risk management purposes as of the balance sheet dates are included in the analysis, but no additional hedging is forecasted. At June 30, 2020, these derivative instruments comprise interest rate swaps that convert $2.7 billion of fixed-rate medium- and long-term debt to variable rates through fair value hedges and convert $5.6 billion of variable-rate loans to fixed rates through cash flow hedges. This base-case net interest income is then compared against interest rate scenarios in which rates rise or decline 100 basis points (with a floor of zero percent) in a linear, non-parallel fashion from the base case over 12 months, resulting in an average increase or decrease in short-term interest rates of 50 basis points over the period.

Each scenario includes assumptions such as loan growth, investment security prepayment levels, depositor behavior, yield curve changes, loan and deposit pricing, and overall balance sheet mix and growth. In this low rate environment, depositors have maintained a higher level of liquidity and their historical behavior may be less indicative of future trends. As a result, the rising rate scenario reflects a greater decrease in deposits than experienced historically as rates rise. Changes in actual economic activity may result in a materially different interest rate environment as well as a balance sheet structure that is different from the changes management included in its simulation analysis.

The table below, as of June 30, 2020 and December 31, 2019, displays the estimated impact on net interest income during the next 12 months by relating the base case scenario results to those from the rising and declining rate scenarios described above.

			June 30, 2020																		December 31, 2019
(dollar amounts in millions)			Amount						%						Amount						%
Change in Interest Rates:												Change in Interest Rates:
Rising 100 basis points			$	130					7		%	Rising 100 basis points			$	90					4		%
Declining to zero percent			(32)						(2)			Declining 100 basis points			(135)						(6)

The change in sensitivity to interest rates from December 31, 2019 to June 30, 2020 was driven by growth in fixed-rate loans, as well as the addition of swaps converting variable-rate loans to fixed rates, partially offset by growth in core deposits. Also, decreased sensitivity to declining interest rates was related to limited downward movement in interest rates before hitting zero percent.

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Sensitivity of Economic Value of Equity to Changes in Interest Rates

In addition to the simulation analysis on net interest income, an economic value of equity analysis provides an alternative view of the interest rate risk position. The economic value of equity is the difference between the estimate of the economic value of the Corporation's financial assets, liabilities and off-balance sheet instruments, derived through discounting cash flows based on actual rates at the end of the period, and the estimated economic value after applying the estimated impact of rate movements. The Corporation primarily monitors the percentage change on the base-case economic value of equity. The economic value of equity analysis is based on an immediate parallel 100 basis point shock.

The table below, as of June 30, 2020 and December 31, 2019, displays the estimated impact on the economic value of equity from the interest rate scenario described above.

			June 30, 2020																		December 31, 2019
(dollar amounts in millions)			Amount						%						Amount						%
Change in Interest Rates:												Change in Interest Rates:
Rising 100 basis points			$	1,319					15		%	Rising 100 basis points			$	716					7		%
Declining to zero percent			(479)						(54)			Declining 100 basis points			(1,178)						(12)

The sensitivity of the economic value of equity to rising rates increased from December 31, 2019 to June 30, 2020 due to changes in deposit pay rates and expected lives. The sensitivity to declining rates decreased due to changes in balance sheet composition as well as limited remaining downward movement in rates before hitting modeled zero-percent floors.

LIBOR Transition

On July 27, 2017, the United Kingdom’s Financial Conduct Authority, which regulates LIBOR, publicly announced that it intends to stop persuading or compelling banks to submit LIBOR rates after 2021. The Corporation has substantial exposure to LIBOR-based products, including loans, securities, derivatives and hedges, and is preparing for a transition from LIBOR toward alternative rates. A dedicated program office and governance structure has been established, with direction and oversight from the Chief Executive Officer, Chief Financial Officer and Chief Risk Officer. A cross-functional implementation team has been tasked with execution of an enterprise LIBOR transition plan road map. Comerica’s enterprise transition milestones align with recommendations from the Alternative Reference Rates Committee (ARRC) for both best practices and recommended 2020 objectives. As of the second quarter of 2020, customer disclosure information for both consumer and commercial loans are being provided for new originations. Execution plans are in place to begin incorporating fallback language related to legacy LIBOR commercial loans by the end of 2020. Additional milestones for products originated on alternative reference rates will be executed in alignment with market and industry decisions. The Corporation continues to monitor market developments and regulatory updates, as well as collaborate with regulators and industry groups on the transition. For a discussion of the various risks facing the Corporation in relation to the transition away from LIBOR, refer to "Item 1A. Risk Factors" beginning on page 12 of the Corporation's 2019 Annual Report.

Wholesale Funding

The Corporation may access the purchased funds market when necessary, which includes a variety of funding sources. Capacity for incremental purchased funds at June 30, 2020 included short-term Federal Home Loan Bank (FHLB) advances, the ability to purchase federal funds, sell securities under agreements to repurchase as well as issue deposits through brokers. Purchased funds increased to $839 million at June 30, 2020 compared to $295 million at December 31, 2019, driven by increases in short-term FHLB advances. At June 30, 2020, the Bank had pledged loans totaling $21.2 billion which provided for up to $16.2 billion of available collateralized borrowing with the Federal Reserve Bank (FRB).

The Bank is a member of the FHLB of Dallas, Texas, which provides short- and long-term funding to its members through advances collateralized by real estate-related assets. Actual borrowing capacity is contingent on the amount of collateral available to be pledged to the FHLB. At June 30, 2020, $18.3 billion of real estate-related loans and $5.2 billion of investment securities were pledged to the FHLB as collateral for current and potential future borrowings. The Corporation had $3.6 billion of FHLB long-term advances, maturing between 2026 and 2028, as well as $750 million in short-term advances outstanding at June 30, 2020, and capacity for potential future borrowings of approximately $10.1 billion. The Corporation expects to repay $1.0 billion of its outstanding FHLB long-term advances in third quarter 2020.

Additionally, the Bank had the ability to issue up to $13.5 billion of debt at June 30, 2020 under an existing $15.0 billion note program which allows the issuance of debt with maturities between three months and 30 years. The Corporation also maintains a shelf registration statement with the Securities and Exchange Commission from which it may issue debt and/or equity securities.

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The ability of the Corporation and the Bank to raise funds at competitive rates may be impacted by rating agencies' views of the credit quality, liquidity, capital and earnings of the Corporation and the Bank. As of June 30, 2020, the three major rating agencies had assigned the ratings below to long-term senior unsecured obligations of the Corporation and the Bank. A security rating is not a recommendation to buy, sell, or hold securities and may be subject to revision or withdrawal at any time by the assigning rating agency. Each rating should be evaluated independently of any other rating.

Comerica Incorporated

Comerica Bank

June 30, 2020

Rating

Outlook

Rating

Outlook

Standard and Poor’s

BBB+

Negative

A-

Negative

Moody’s Investors Service

A3

Stable

A3

Stable

Fitch Ratings

A-

Stable

A-

Stable

The Corporation satisfies liquidity needs with either liquid assets or various funding sources. Liquid assets totaled $20.5 billion and $17.9 billion at June 30, 2020 and December 31, 2019, respectively. Liquid assets include cash and due from banks, federal funds sold, interest-bearing deposits with banks, other short-term investments and unencumbered investment securities.

The Corporation performs monthly liquidity stress testing to evaluate its ability to meet funding needs in hypothetical stressed environments. Such environments cover a series of broad events, distinguished in terms of duration and severity. The evaluation as of June 30, 2020 projected sufficient sources of liquidity were available under each series of events.

Total liquidity sources, comprised of liquid assets and remaining borrowing capacity with the FRB and the FHLB, totaled $46.8 billion at June 30, 2020.

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CRITICAL ACCOUNTING POLICIES

The Corporation’s consolidated financial statements are prepared based on the application of accounting policies, the most significant of which are described in Note 1 to the consolidated financial statements included in the Corporation's 2019 Annual Report. These policies require numerous estimates and strategic or economic assumptions, which may prove inaccurate or subject to variations. Changes in underlying factors, assumptions or estimates could have a material impact on the Corporation’s future financial condition and results of operations. At December 31, 2019, the most critical of these significant accounting policies were the policies related to the allowance for credit losses, fair value measurement, goodwill, pension plan accounting and income taxes. These policies were reviewed with the Audit Committee of the Corporation’s Board of Directors and are discussed more fully on pages F-34 through F-36 in the Corporation's 2019 Annual Report. Below are significant changes to the Corporation's critical accounting policies or estimates since the Corporation's 2019 Annual Report.

ALLOWANCE FOR CREDIT LOSSES

The Corporation adopted new accounting guidance for estimating credit losses, known as the CECL framework, in first quarter 2020. In accordance with CECL, the allowance for credit losses, which includes both the allowance for loan losses and the allowance for credit losses on lending-related commitments, is calculated with the objective of maintaining a reserve for current expected credit losses over the remaining contractual life of the portfolio.

In determining the allowance for credit losses for the majority of its lending portfolio, the Corporation uses reserve factors, based on estimated probability of default for internal risk ratings and loss given default. Management applies reserve factors to pools of loans and lending-related commitments with similar risk characteristics, calibrates these factors using economic forecasts and incorporates qualitative adjustments. For further discussion of the methodology used in the determination of the allowance for credit losses, refer to Note 1 to the consolidated financial statements. For further discussion on the economic forecast incorporated into the second quarter 2020 model, refer to the “Risk Management” section of this report.

Management's determination of the appropriateness of the allowance is based on periodic evaluations of the loan portfolio, lending-related commitments, current as well as forecasted economic factors and other relevant factors. The calculation is inherently subjective and requires management to exercise significant judgment in developing assumptions into the estimate, the most significant of which are the loan risk rating process, development of economic forecasts and application of qualitative adjustments. Sensitivities are disclosed to demonstrate how changes in loan risk ratings and economic forecast scenarios may impact the allowance for credit losses. Sensitivities only consider changes to each specific assumption in isolation and their impact to the quantitative modeled results; however, they do not contemplate impacts to the qualitative framework.

Loan Risk Rating Process

Loss factors are applied to pools of loans based on the Corporation's internal risk rating system; therefore, loss estimates are highly dependent on the accuracy of the risk rating assigned to each loan. The inherent imprecision in the risk rating system resulting from inaccuracy in assigning and/or entering risk ratings in the loan accounting system is monitored by the Corporation's asset quality review function. Changes to internal risk ratings, beyond the forecasted migration inherent in the credit models, would result in a different estimated allowance for credit losses. To illustrate, if five percent of the individual risk ratings were adjusted down by one rating across all pools, the allowance for loan losses as of June 30, 2020 would change by approximately $13 million.

Forecasted Economic Variables

Historical loss factor estimates are calibrated to economic forecasts over the reasonable and supportable forecast period based on the projected performance of specific economic variables that statistically correlate with the probability of default and loss given default pools. Loss estimates revert to historical loss experience for contractual lives beyond the forecast period. Management selects economic variables it believes to be most relevant based on the composition of the loan portfolio and customer base, including forecasted levels of employment, gross domestic product, corporate bond and treasury spreads, industrial production levels, consumer and commercial real estate price indices as well as housing statistics.

The allowance for credit losses is highly sensitive to the economic forecasts used to develop the estimate. Due to the high level of uncertainty regarding significant assumptions, such as the ultimate impact of the global pandemic and effectiveness of the government stimulus, the Corporation evaluated a range of economic scenarios, including a more severe economic forecast scenario, with varying speeds of recovery. The following table summarizes the more severe forecast scenario for the economic variables that are most impactful.

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Economic Variable			More Severe Forecast
Real GDP growth			Grows by 13 percent in third quarter 2020 followed by a short-term contraction, then reaches a growth rate of 7 percent as the forecast period ends part-way through an economic recovery.
Unemployment rate			Remains at elevated levels between 10 percent and 12 percent throughout the forecast period.
Corporate BBB bond to 10-year Treasury bond spreads			Remains between 3.75 percent and 4.15 percent in the near-term before normalizing into spreads below 2 percent by the end of the forecast period.
Oil Prices			Price remains low throughout the forecast period, improving to above $25 per barrel by the second quarter 2022.

Selecting a different forecast in the current environment could result in significantly different estimated allowance for credit losses. To illustrate, absent model overlays and other qualitative adjustments that are part of the quarterly reserving process, if the Corporation selected the more severe scenario to inform its models, the allowance for credit losses as of June 30, 2020 would increase by approximately $1.6 billion. However, factoring in model overlays and qualitative adjustments could result in a materially different estimate under a more severe scenario.

Qualitative Adjustments

The Corporation includes qualitative adjustments, as appropriate, intended to capture the impact of uncertainties not reflected in the quantitative estimate, including foresight risk, model imprecisions and input imprecisions. Qualitative adjustments for foresight risk, reflect the inherent imprecision in economic forecasts and may be included based on management’s evaluation of different forecast scenarios, ranging from more benign to more severe, and known recent events impacting the Corporation’s portfolio. Model imprecision adjustments and model overlays may be included to mitigate known limitations in the quantitative models. Input imprecision includes adjustments for portfolios where recent historical losses exceed expected losses or known recent events are expected to alter risk ratings once evidence is acquired, as well as a qualitative assessment of the lending environment, including underwriting standards, current economic and political conditions, and other factors affecting credit quality. Qualitative reserves at June 30, 2020 primarily included adjustments for uncertainties related to forecasted economic variables and model imprecision.

Other Considerations

To the extent actual outcomes differ from management estimates, additional provision for credit losses may be required that would adversely impact earnings in future periods. The allowance is assigned to business segments and any earnings impact resulting from actual outcomes differing from management estimates would primarily affect the Commercial Bank segment.

GOODWILL

Goodwill is initially recorded as the excess of the purchase price over the fair value of net assets acquired in a business combination and is subsequently evaluated at least annually for impairment. Goodwill impairment testing is performed at the reporting unit level, equivalent to a business segment or one level below. The Corporation has three reporting units: the Commercial Bank, the Retail Bank and Wealth Management. At June 30, 2020, goodwill totaled $635 million, including $473 million allocated to the Commercial Bank, $101 million allocated to the Retail Bank and $61 million allocated to Wealth Management.

The Corporation performs its annual evaluation of goodwill impairment in the third quarter of each year and may elect to perform a quantitative impairment analysis or first conduct a qualitative analysis to determine if a quantitative analysis is necessary. Additionally, the Corporation evaluates goodwill impairment on an interim basis if events or changes in circumstances between annual tests indicate additional testing may be warranted to determine if goodwill might be impaired.

In the first quarter of 2020, economic conditions deteriorated significantly with the spread of the coronavirus global pandemic. The outbreak resulted in social distancing requirements throughout the world, severely restricting the economy. In response to the crisis, the Federal Reserve lowered the Federal Funds rate in March 2020 to close to zero. Additionally, the U.S. government initiated numerous measures to support the economy, including the CARES Act. Given the economic deterioration in the first quarter of 2020, the Corporation assessed whether the events and circumstances resulted in it being more likely than not that the fair value of any reporting unit was less than its carrying value. Impairment indicators considered comprised economic conditions, including projections of the duration of current conditions and timing of a potential recovery; industry and market considerations; government intervention and regulatory updates; the impact of recent events to financial performance and cost factors of the reporting units; performance of the Corporation’s stock and other relevant events. The Corporation further considered the amount by which fair value exceeded book value for each unit in the most recent quantitative analysis

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and sensitivities performed. At the conclusion of the first quarter 2020 assessment, the Corporation determined that it was more likely than not that the fair value of each reporting unit exceeded its carrying value.

In second quarter 2020, the Corporation performed a quantitative goodwill impairment test in response to continued macroeconomic deterioration and the ongoing impacts to the banking industry and markets in which the Corporation operates. The estimated fair values of the reporting units were determined using a blend of two commonly used valuation techniques: the market approach and the income approach. For the market approach, valuations of reporting units considered a combination of earnings and equity multiples from companies with characteristics similar to the reporting unit. Since the fair values determined under the market approach are representative of noncontrolling interests, the valuations incorporated a control premium. For the income approach, estimated future cash flows were derived from internal forecasts and economic expectations for each reporting unit. In the short- and mid-term, forecasts incorporated current economic conditions and ongoing impacts of the global pandemic, including a federal funds target near zero and an elevated allowance for credit losses. Long-term projections reflected normalized rate and credit environments, as well as a long-term rate of return for each reporting unit. Projections were discounted using an applicable discount rate to calculate fair value. The discount rate was based on the imputed cost of equity capital appropriate for each reporting unit, which incorporates the risk-free rate of return, the level of non-diversified risk associated with companies with characteristics similar to the reporting unit, a size risk premium and a market equity risk premium. The discount rate further reflected the uncertainty of current economic conditions and potential impacts to the forecasted financial information. The combined fair value of all units was compared to the Corporation’s market capitalization for reasonableness. At the conclusion of the quantitative impairment test in second quarter 2020, the estimated fair values of all reporting units substantially exceeded their carrying amounts, including goodwill.

The test included evaluation of various factors that continue to rapidly evolve and for which significant uncertainty remains, including the impact of the coronavirus global pandemic to the economy and ongoing government intervention to mitigate that impact. Further weakening in the economic environment, such as continued decline in the performance of the reporting units or other factors, could cause the fair value of one or more of the reporting units to fall below their carrying value, resulting in a goodwill impairment charge. Additionally, new legislative or regulatory changes not anticipated in management's expectations may cause the fair value of one or more of the reporting units to fall below the carrying value, resulting in a goodwill impairment charge. Any impairment charge would not affect the Corporation's regulatory capital ratios, tangible common equity ratio or liquidity position.

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SUPPLEMENTAL FINANCIAL DATA

The Corporation believes non-GAAP measures are meaningful because they reflect adjustments commonly made by management, investors, regulators and analysts to evaluate the adequacy of common equity and our performance trends. Tangible common equity is used by the Corporation to measure the quality of capital and the return relative to balance sheet risk.

Common equity tier 1 capital ratio removes preferred stock from the Tier 1 capital ratio as defined by and calculated in conformity with bank regulations. The tangible common equity ratio removes the effect of intangible assets from capital and total assets. Tangible common equity per share of common stock removes the effect of intangible assets from common shareholders' equity per share of common stock.

The following table provides a reconciliation of non-GAAP financial measures and regulatory ratios used in this financial review with financial measures defined by GAAP.

(dollar amounts in millions)			June 30, 2020						December 31, 2019
Common Equity Tier 1 Capital (a):
Tier 1 capital			$	7,093					$	6,919
Less:
Fixed-rate reset non-cumulative perpetual preferred stock			395						—
Common equity tier 1 capital			$	6,698					$	6,919
Risk-weighted assets			$	67,156					$	68,273
Tier 1 capital ratio			10.56		%				10.13		%
Common equity tier 1 capital ratio			9.97						10.13
Tangible Common Equity Ratio:
Total shareholders' equity			$	7,802					$	7,327
Less:
Fixed-rate non-cumulative perpetual preferred stock			395						—
Goodwill			635						635
Other intangible assets			3						4
Tangible common equity			$	6,769					$	6,688
Total assets			$	84,397					$	73,402
Less:
Goodwill			635						635
Other intangible assets			3						4
Tangible assets			$	83,759					$	72,763
Common equity ratio			8.78		%				9.98		%
Tangible common equity ratio			8.08						9.19
Tangible Common Equity per Share of Common Stock:
Common shareholders' equity			$	7,407					$	7,327
Tangible common equity			6,769						6,688
Shares of common stock outstanding (in millions)			139						142
Common shareholders' equity per share of common stock			$	53.28					$	51.57
Tangible common equity per share of common stock			48.69						47.07

(a)Tier 1 capital as defined by regulation; estimated for June 30, 2020, reflects deferral of CECL model impact.  

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ITEM 3. Quantitative and Qualitative Disclosures about Market Risk

Quantitative and qualitative disclosures for the current period can be found in the "Market and Liquidity Risk" section of "Item 2. Management's Discussion and Analysis of Financial Condition and Results of Operations."

ITEM 4. Controls and Procedures

(a)Evaluation of Disclosure Controls and Procedures. The Corporation maintains a set of disclosure controls and procedures (as defined in Rules 13a-15(e) and 15d-15(e) under the Securities Exchange Act of 1934, as amended (the "Exchange Act")) that are designed to ensure that information required to be disclosed by the Corporation in the reports that it files or submits under the Exchange Act is recorded, processed, summarized and reported within the time periods specified in the Securities and Exchange Commission's rules and forms, and that such information is accumulated and communicated to the Corporation's management, including the Corporation's Chief Executive Officer and Chief Financial Officer, as appropriate, to allow timely decisions regarding required disclosure. Management has evaluated, with the participation of the Corporation's Chief Executive Officer and Chief Financial Officer, the effectiveness of the Corporation's disclosure controls and procedures as of the end of the period covered by this quarterly report (the "Evaluation Date"). Based on the evaluation, the Corporation's Chief Executive Officer and Chief Financial Officer have concluded that, as of the Evaluation Date, the Corporation's disclosure controls and procedures are effective.

(b)Changes in Internal Control Over Financial Reporting. During the period to which this report relates, there have not been any changes in the Corporation's internal control over financial reporting (as defined in Rules 13a-15(f) and 15d-15(f) under the Exchange Act) that have materially affected, or that are reasonably likely to materially affect, such controls.

PART II. OTHER INFORMATION

ITEM 1. Legal Proceedings

For information regarding the Corporation's legal proceedings, see "Part I. Item 1. Note 12 – Contingent Liabilities," which is incorporated herein by reference.

ITEM 1A. Risk Factors

        Other than as set forth below, there have been no material changes in the Corporation’s risk factors as previously disclosed in our Form 10-K for the fiscal year ended December 31, 2019 in response to Part I, Item 1A. of such Form 10-K. Such risk factors are incorporated herein by reference.  

        The following risk factor is added under "General Risk":

•The COVID-19 pandemic has impacted our business, and the ultimate impact on our business and financial results will depend on future developments, which are highly uncertain and cannot be predicted, including the scope and duration of the pandemic and actions taken by governmental authorities in response to the pandemic.

The COVID-19 pandemic has negatively impacted the global economy, disrupted global supply chains, lowered equity market valuations, created significant volatility and disruption in financial markets, and increased unemployment levels. In addition, the pandemic has resulted in temporary closures of many businesses and the institution of social distancing and sheltering in place requirements in many states and communities. As a result, the demand for our products and services may be significantly impacted. Furthermore, the pandemic has influenced and could further influence the recognition of credit losses in our loan portfolios and has increased and could further increase our allowance for credit losses, particularly as businesses remain closed and as more customers may draw on their lines of credit or seek additional loans to help finance their businesses. Similarly, because of changing economic and market conditions affecting issuers, the securities we hold may lose value. Our business operations may also be disrupted if significant portions of our workforce are unable to work effectively, including because of illness, quarantines, government actions, or other restrictions in connection with the pandemic, and we have already temporarily closed certain of our branches and offices. In response to the pandemic, we have also enacted hardship relief assistance for customers experiencing financial difficulty as a result of COVID-19, including fee and penalty waivers, loan deferrals or other scenarios that may help our customers. As well, we are a lender for the Small Business Administration's Paycheck Protection Program ("PPP") and other SBA, Federal Reserve or United States Treasury programs that have been or may be created in the future in response to the pandemic. These programs are new and

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their effects on Comerica's business are uncertain. The extent to which the COVID-19 pandemic impacts our business, results of operations, and financial condition, as well as our regulatory capital and liquidity ratios, will depend on future developments, which are highly uncertain and cannot be predicted, including the scope and duration of the pandemic and actions taken by governmental authorities and other third parties in response to the pandemic.

        Below we amend the following risk factor discussed under "Credit Risk" in Part II, "Item 1A. Risk Factors" in Part I, Item 1A. of our Form 10-K for the fiscal year ended December 31, 2019.

•Declines in the businesses or industries of Comerica's customers - in particular, the energy industry - could cause increased credit losses or decreased loan balances, which could adversely affect Comerica.

Comerica's business customer base consists, in part, of customers in volatile businesses and industries such as the automotive, commercial real estate, residential real estate and energy industries. These industries are sensitive to global economic conditions, supply chain factors and/or commodities prices. Any decline in one of these businesses or industries could cause increased credit losses, which in turn could adversely affect Comerica. Further, any decline in these businesses or industries could cause decreased borrowings, either due to reduced demand or reductions in the borrowing base available for each customer loan.

In particular, oil and gas prices have fallen since the beginning of 2020 due to global events. Loans in the Energy business line were $2.1 billion, or approximately 4 percent of total loans, at June 30, 2020. At June 30, 2020, the reserve allocation for Energy loans was over 10 percent of total Energy loans. If oil and gas prices continue to remain depressed for a prolonged period of time, Comerica's energy portfolio could experience increased credit losses, which could adversely affect Comerica's financial results. Furthermore, a prolonged period of low oil prices could also have a negative impact on the Texas economy, which could have a material adverse effect on Comerica’s business, financial condition and results of operations. For more information regarding Comerica's energy portfolio, please see “Energy Lending” beginning on page 56 of this report.

For more information regarding certain of Comerica's lines of business, please see "Concentration of Credit Risk," "Automotive Lending," "Commercial Real Estate Lending," "Residential Real Estate Lending" and “Energy Lending” on pages F-25 through F-27 of Comerica’s Form 10-K for the fiscal year ended December 31, 2019.  

ITEM 2. Unregistered Sales of Equity Securities and Use of Proceeds

For information regarding the Corporation's purchase of equity securities, see "Part I. Item 2. Management's Discussion and Analysis of Financial Condition and Results of Operations – Capital," which is incorporated herein by reference.

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ITEM 6. Exhibits

Exhibit No.						Description
3.1						Restated Certificate of Incorporation of Comerica Incorporated (filed as Exhibit 3.2 to Registrant's Current Report on Form 8-K dated August 4, 2010, and incorporated herein by reference).
3.2						Certificate of Amendment to Restated Certificate of Incorporation of Comerica Incorporated (filed as Exhibit 3.2 to Registrant's Quarterly Report on Form 10-Q for the quarter ended March 31, 2011, and incorporated herein by reference).
3.3						Amended and Restated Bylaws of Comerica Incorporated (filed as Exhibit 3.3 to Registrant's Current Report on Form 8-K dated April 9, 2020, and incorporated herein by reference).
3.4						Certificate of Designations of 5.625% Fixed-Rate Reset Non-Cumulative Perpetual Preferred Stock, Series A, dated May 26, 2020, of Comerica Incorporated (including the form of 5.625% Fixed-Rate Reset Non-Cumulative Perpetual Preferred Stock, Series A Certificate of Comerica Incorporated attached as Exhibit A thereto) (filed as Exhibit 3.1 to Registrant's Current Report on Form 8-K dated May 26, 2020, and incorporated herein by reference).
4						[In accordance with Regulation S-K Item No. 601(b)(4)(iii), the Registrant is not filing copies of instruments defining the rights of holders of long-term debt because none of those instruments authorizes debt in excess of 10% of the total assets of the registrant and its subsidiaries on a consolidated basis. The Registrant hereby agrees to furnish a copy of any such instrument to the SEC upon request.]
4.1						Deposit Agreement, dated May 26, 2020, among Comerica Incorporated, Computershare Inc., Computershare Trust Company, N.A. and the holders from time to time of the depositary receipts issued thereunder (including the form of depositary share receipt attached as Exhibit A thereto) (filed as Exhibit 4.1 to Registrant's Current Report on Form 8-K dated May 26, 2020, and incorporated herein by reference).
10.1H†						Form of Standard Comerica Incorporated Restricted Stock Agreement (cliff vesting) under the Comerica Incorporated 2018 Long-Term Incentive Plan (2-year version).
10.11†						Amended and Restated Comerica Incorporated Non-Employee Director Fee Deferral Plan (amended and restated effective July 1, 2020).
10.12†						Amended and Restated Comerica Incorporated Common Stock Non-Employee Director Fee Deferral Plan (amended and restated effective July 1, 2020).
31.1						Chairman, President and CEO Rule 13a-14(a)/15d-14(a) Certification of Periodic Report (pursuant to Section 302 of the Sarbanes-Oxley Act of 2002).
31.2						Executive Vice President and CFO Rule 13a-14(a)/15d-14(a) Certification of Periodic Report (pursuant to Section 302 of the Sarbanes-Oxley Act of 2002).
32						Section 1350 Certification of Periodic Report (pursuant to Section 906 of the Sarbanes-Oxley Act of 2002).
101						Financial statements from Quarterly Report on Form 10-Q of the Registrant for the quarter ended June 30, 2020, formatted in Inline XBRL: (i) the Consolidated Balance Sheets (unaudited), (ii) the Consolidated Statements of Comprehensive Income (unaudited), (iii) the Consolidated Statements of Changes in Shareholders' Equity (unaudited), (iv) the Consolidated Statements of Cash Flows (unaudited) and (v) the Notes to Consolidated Financial Statements (unaudited).
104						The cover page from the Registrant's Quarterly Report on Form 10-Q for the quarter ended June 30, 2020, formatted in Inline XBRL (included in Exhibit 101).
†						Management contract or compensatory plan or arrangement.

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SIGNATURE

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned thereunto duly authorized.

			COMERICA INCORPORATED
			(Registrant)
			/s/ Mauricio A. Ortiz
			Mauricio A. Ortiz
			Senior Vice President and
			Chief Accounting Officer and
			Duly Authorized Officer

Date: July 30, 2020

68

Exhibit 10.1H

COMERICA INCORPORATED

RESTRICTED STOCK UNIT AWARD AGREEMENT (CLIFF)

THIS AGREEMENT (this “Agreement”) between Comerica Incorporated (the “Company”) and XXXXXX (the “Participant”) is effective as of XXXXXX (the “Effective Date”). Any undefined terms appearing herein as defined terms shall have the same meaning as they do in the Comerica Incorporated 2018 Long-Term Incentive Plan, as amended and/or restated from time to time, or any successor plan thereto (the “Plan”). The Company shall provide a copy of the Plan to the Participant upon request.

WITNESSETH:

1.Award of Restricted Stock Units. Pursuant to the provisions of the Plan, the Company hereby awards the Participant, subject to the terms and conditions of the Plan (incorporated herein by reference), and subject further to the terms and conditions in this Agreement, XXXXXX restricted stock units (“RSUs”) (the “Award”). Each RSU shall represent an unfunded, unsecured right for the Participant to receive one (1) Share, as described in this Agreement.

2.Ownership Rights. The Participant shall have no voting or other ownership rights in the Company arising from the Award of RSUs under this Agreement prior to the delivery of Shares upon the vesting and settlement of RSUs underlying the Award.

3.Dividend Equivalents. If cash dividends are declared by the Board on the Common Stock on or after the Effective Date and prior to the Settlement Date (as defined below), cash dividend equivalents (the “Dividend Equivalents”) shall accrue on the Shares underlying RSUs, whether such RSUs are vested or unvested, which Dividend Equivalents shall be subject to vesting and forfeiture on the same terms and conditions as the underlying RSUs. Such Dividend Equivalents shall be in an amount of cash per RSU equal to the cash dividend paid with respect to each outstanding Share and shall be credited on the declaration date applicable to Shares. The Dividend Equivalents accrued prior to the Settlement Date shall be paid to the Participant with respect to all vested RSUs as soon as administratively feasible (and in no event more than forty-five (45) days) following the Settlement Date. The Dividend Equivalents accrued on Shares underlying RSUs that do not vest and are forfeited shall be forfeited for no consideration on the date such RSU is forfeited.

4.Vesting of Award.

a.General. Except as otherwise provided in the Plan and this Agreement, 100% of the RSUs covered by the Award shall vest on the second anniversary of the Effective Date (or, if such date is not a business day, the business day immediately preceding such date) (the “Vesting Date”), subject to the Participant’s continued employment by the Company or one of its Affiliates through the Vesting Date.

b.Death or Disability. In the event of the Participant’s Termination of Service due to death or Disability, prior to the Vesting Date, the Award shall immediately and fully vest effective as of the date of the Participant’s Termination of Service.

c.Change in Control. To the extent a Replacement Award is provided pursuant to Section 10(c) of the Plan, upon a Termination of Service of the Participant by the Company other than for Cause or by the Participant for Good Reason (as defined below), in each case, prior to the Vesting Date and within twenty-four (24) months following a Change in Control, the Award shall immediately and fully vest effective as of the date of the Participant’s Termination of Service. If a Replacement Award is not provided in respect of the Award, the vesting provisions set forth in Section 10(b) of the Plan shall apply.

Notwithstanding any provision of the Plan or any other agreement to the contrary, for purposes of this Agreement, the term “Good Reason” means the occurrence of any of the following without the Participant’s consent: (i) a material reduction in the Participant’s annual base salary or target short-term incentive compensation opportunity, in each case, from that in effect immediately prior to the Change in Control; or (ii) a mandatory relocation of the Participant’s principal location of employment to a location that is more than fifty (50) miles from his or her principal employment location immediately prior to the Change in Control and increases the distance between the Participant’s home and principal employment

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location. In order to invoke a termination for Good Reason, the Participant shall provide written notice to the Company of the existence of one or more of the conditions described in clauses (i) or (ii) within ninety (90) days following the Participant’s knowledge of the initial existence of such condition or conditions, and the Company shall have thirty (30) days following receipt of such written notice (the “Cure Period”) during which it may cure the condition, if curable. If the Company fails to cure the condition constituting Good Reason during the Cure Period, the Participant must terminate employment, if at all, within one (1) year following the end of the Cure Period in order for such termination to constitute a termination for Good Reason. The Participant’s mental or physical incapacity following the occurrence of an event described above in clauses (i) or (ii) shall not affect the Participant’s ability to terminate employment for Good Reason.

d.All Other Terminations. Except as provided in this Section 4, if the Participant’s Termination of Service occurs prior to the Vesting Date, the Award shall be forfeited for no consideration effective immediately as of the date of Termination of Service, unless the Committee determines otherwise.

5.Special Vesting and Forfeiture Terms.

a.Forfeiture Resulting from Acts Occurring During the Grant Year. Notwithstanding any other provision of this Agreement, if it shall be determined at any time subsequent to the Effective Date and prior to the Settlement Date (or, in the case of a termination due to death or Disability, the date of Termination of Service) that the Participant has, during the calendar year in which the Effective Date occurs (the “Grant Year”), (i) failed to comply with Company policies and procedures, including the Code of Business Conduct and Ethics or the Senior Financial Officer Code of Ethics (if applicable), (ii) violated any law or regulation, (iii) engaged in negligent or willful misconduct, (iv) engaged in activity resulting in a significant or material Sarbanes-Oxley control deficiency, or (v) demonstrated poor risk management or lack of judgment in discharge of Company duties, and such failure, violation, misconduct, activity or behavior (1) demonstrates an inadequate sensitivity to the inherent risks of Participant’s business line or functional area, and (2) results in, or is reasonably likely to result in, a material adverse impact (whether financial or reputational) on the Company or Participant’s business line or functional area, all or part of the Award granted under this Agreement that has not yet become vested at the time of such determination may be cancelled and forfeited. “Inadequate sensitivity” to risk is demonstrated by imprudent activities that subject the Company to risk outcomes in future periods, including risks that may not be apparent at the time the activities are undertaken.

b.Forfeiture of Award for Acts Occurring in Years Other Than the Grant Year. Notwithstanding any other provisions of this Agreement, if the Participant receives one or more equity awards in any calendar years other than the Grant Year (an “Other Grant Year”) pursuant to an Award Agreement that contains a clause substantially similar to Section 5(a) above, and it shall be determined that Participant, as a result of risk-related behavior, should be subject to the forfeiture of all or part of any such award granted in such Other Grant Year in accordance with the terms of such clause, then the unvested portion of the Award granted under this Agreement shall be subject to forfeiture to the extent necessary to equal the Unsatisfied Forfeiture Value (as defined below). The term “Unsatisfied Forfeiture Value” shall mean the value (as determined by the Committee in its absolute discretion) of any portion of the Award determined by the Committee to be subject to forfeiture with respect to the Other Grant Year (without regard to whether or not some portion thereof has already vested) that has in fact vested prior to such determination by the Committee. All or a portion of the RSUs granted under this Agreement that have not yet become vested shall be subject to forfeiture in order to satisfy as much as possible of the Unsatisfied Forfeiture Value, and the valuation of the Award for such purpose shall be determined in the absolute discretion of the Committee.

6.Settlement. Once vested, the Award shall be settled as follows:

a.In General. Subject to the terms of the Plan and this Agreement, the Award shall be settled in Common Stock as soon as reasonably practicable (and in no event more than forty-five (45) days) following the date on which the Award vests (the “Settlement Date”). On the Settlement Date, the Company shall issue to the Participant (or, in the case of the Participant’s death, to the Participant’s designated beneficiary pursuant to Section 13(f) of the Plan, as applicable or, in the case of the Participant’s

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Restricted Stock Unit Award Agreement (Cliff)			Page 3 of 5

Disability, to the Participant’s guardian or legal representative, if applicable and if permissible under applicable law) a number of whole Shares equal to the aggregate number of RSUs in respect of the Award (the “Settlement Shares”). Nothing herein shall preclude the Company from settling the RSUs upon a Section 409A CIC, if they are not replaced by a Replacement Award, to the extent such settlement is effectuated in accordance with Treas. Regs. § 1.409A-3(j)(4)(ix)(B).

b.Termination of Rights. Upon the issuance of the Settlement Shares in settlement of the vested RSUs in respect of the Award, the Award shall be settled in full and the Participant (or his or her designated beneficiary pursuant to Section 13(f) of the Plan, in the case of death) shall have no further rights with respect to the Award, other than with respect to the payment of the Dividend Equivalents accrued with respect to such vested RSUs.

7.Withholding. The Participant authorizes the Company to withhold from his or her compensation, including RSUs subject to the Award and the Settlement Shares issuable hereunder, to satisfy any income and employment tax withholding obligations in connection with the Award. No later than the date as of which an amount first becomes includible in the gross income of the Participant for Federal income tax purposes with respect to any Settlement Shares subject to the Award, the Participant shall pay to the Company, or make arrangements satisfactory to the Company regarding the payment of, all Federal, state and local income and employment taxes that are required by applicable laws and regulations to be withheld with respect to such amount. The Participant agrees that the Company may delay delivery of the Settlement Shares until proper payment of such taxes has been made by the Participant. If required pursuant to the Company’s policy as applied to the Participant or elected by the Participant, to the extent permitted by law, tax withholding obligations in respect of the Award shall be satisfied by authorizing the Company to withhold (provided the amount withheld does not exceed the maximum statutory tax rate in the Participant’s applicable tax jurisdiction or such lesser amount as is necessary to avoid adverse accounting treatment for the Company) from the Settlement Shares otherwise issuable to the individual pursuant to the settlement of the Award, a number of Shares having a Fair Market Value, as of the date the obligation to withhold such taxes arises, which will satisfy the amount of the withholding tax obligation. Further, unless determined otherwise by the Committee, the Participant may satisfy such obligations under this Section 7 by any other method authorized under Section 13(d) of the Plan.

8.Section 409A of the Code.

a.The Award is intended to qualify for the “short-term deferral” exception under Section 409A of the Code. To the extent that the Award is construed to be nonqualified deferred compensation subject to Section 409A of the Code, the Company shall use its reasonable efforts to operate, administer, construe and interpret this Agreement in a manner that minimizes adverse tax consequences to the Participant and is consistent with the requirements of Section 409A of the Code. Each payment of compensation under this Agreement shall be treated as a separate payment of compensation. In no event may the Participant, directly or indirectly, designate the calendar year of any payment or distribution under this Agreement. Notwithstanding any other provision of the Plan or this Agreement to the contrary, if the Participant is a “specified employee” within the meaning of Section 409A of the Code (as determined in accordance with the methodology established by the Company), amounts that constitute “nonqualified deferred compensation” subject to Section 409A of the Code that would otherwise be payable by reason of the Participant's Termination of Service during the six (6)-month period immediately following such Termination of Service shall instead be paid or provided on the first business day following the date that is six (6) months following the Participant’s Termination of Service. If the Participant dies following the Termination of Service and prior to the payment of any amounts delayed on account of Section 409A of the Code, such amounts shall be paid to the designated beneficiary of the Participant pursuant to Section 13(f) of the Plan within forty-five (45) days following the date of the Participant's death.

b.This Agreement shall be subject to amendment, with or without advance notice to the Participant, and on a prospective or retroactive basis, including, but not limited to, amendment in a manner that adversely affects the rights of the Participant, to the extent necessary to effect compliance with Section 409A of the Code. Notwithstanding anything contained in this Agreement or the Plan, the Company shall have no liability whatsoever for or in respect of any decision to take action to attempt to comply with Section 409A of the Code, any omission to take such action or for the failure of any such action taken by the Company to so comply.

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9.Cancellation of Award. The Committee has the right to cancel for no consideration all or any portion of the Award in accordance with Section 2(d) of the Plan if the Committee determines in good faith that the Participant has done any of the following: (i) been convicted of, or plead guilty or nolo contendere to, a charge of commission of a felony under federal law or the law of the state in which such action occurred; (ii) committed fraud; (iii) embezzled; (iv) disclosed confidential information or trade secrets; (v) was terminated for Cause; (vi) engaged in any activity in competition with the business of the Company or any Subsidiary or Affiliate of the Company; or (vii) engaged in conduct that adversely affected the Company.

The Delegate shall have the power and authority to suspend the vesting of or the right to receive the Settlement Shares in respect of all or any portion of the Award if the Delegate makes in good faith the determination described in the preceding sentence. Any such suspension of an Award shall remain in effect until the suspension shall be presented to and acted on by the Committee at its next meeting. This Section 9 shall have no application following a Change in Control.

10.Compliance with Laws and Regulations. The Award and the obligation of the Company to deliver the Settlement Shares subject to the Award are subject to compliance with all applicable laws, rules and regulations, to receipt of any approvals by any government or regulatory agency as may be required, and to any determinations the Company may make regarding the application of all such laws, rules and regulations.

11.Binding Nature of Plan. The Award is subject to the Plan. The Participant agrees to be bound by all terms and provisions of the Plan and related administrative rules and procedures, including, without limitation, terms and provisions and administrative rules and procedures adopted and/or modified after the granting of the Award. If any provisions hereof are inconsistent with those of the Plan, the provisions of the Plan shall control, except to the extent expressly modified herein pursuant to authority granted under the Plan.

12.Notices. Any notice to the Company under this Agreement shall be in writing to the following address or facsimile number: Human Resources - Total Rewards, Comerica Incorporated, 1717 Main Street, MC 6515, Dallas, TX 75201; Facsimile Number: 214-462-4430. The Company shall address any notice to the Participant to his or her current address according to the Company’s personnel files. All written notices provided in accordance with this Section 12 shall be deemed to be given when (a) delivered to the appropriate address(es) by hand or by a nationally recognized overnight courier service (costs prepaid); (b) sent by facsimile to the appropriate facsimile number, with confirmation by telephone of transmission receipt; or (c) received by the addressee, if sent by U.S. mail to the appropriate address or by Company inter-office mail to the appropriate mail code. Either party may designate in writing some other address or facsimile number for notice under this Agreement.

13.Force and Effect. The various provisions of this Agreement are severable in their entirety. Any judicial or legal determination of invalidity or unenforceability of any one provision shall have no effect on the continuing force and effect of the remaining provisions.

14.Successors. This Agreement shall be binding upon and inure to the benefit of the successors of the respective parties.

15.No Right to Continued Employment. Nothing in the Plan or this Agreement shall confer on the Participant any right to continue in the employment of the Company or its Affiliates for any given period or on any specified terms nor in any way affect the Company’s or its Affiliates’ right to terminate the Participant’s employment without prior notice at any time for any reason or for no reason.

16.Voluntary Participation. Participation in the Plan is voluntary. The value of the Award is an extraordinary item of compensation outside the scope of the Participant’s employment contract, if any. As such, the Award is not part of normal or expected compensation for purposes of calculating any severance, resignation, redundancy, end of service payments, bonuses, long-service awards, pension or retirement benefits or similar payments.

17.Recoupment. In addition to the cancellation provisions of Sections 5 and 9, RSUs granted pursuant to this Agreement shall be subject to the terms of the recoupment (clawback) policy adopted by the Company as in effect from time to time, as well as any recoupment/forfeiture provisions required by law and applicable to the Company or its subsidiaries; provided, however, unless prohibited by applicable law, the Company’s recoupment (clawback) policy shall have no application to the Award following a Change in Control.

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IN WITNESS WHEREOF, this Agreement has been executed by an appropriate officer of Comerica Incorporated and accepted by the Participant, both as of the day and year first above written.

COMERICA INCORPORATED

By:________________________
Name:
Title:

Exhibit 10.11

Governance, Compensation and Nominating Committee Approval: June 24, 2020

Board Approval: July 28, 2020

AMENDED AND RESTATED COMERICA INCORPORATED

NON-EMPLOYEE DIRECTOR FEE DEFERRAL PLAN

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AMENDED AND RESTATED COMERICA INCORPORATED

NON-EMPLOYEE DIRECTOR FEE DEFERRAL PLAN

TABLE OF CONTENTS

SECTION I PURPOSE			1
SECTION II DEFINITIONS			1
SECTION III ELIGIBILITY			3
SECTION IV PROCEDURES RELATING TO DEFERRALS			3
SECTION V CREDITING AND ADJUSTING ACCOUNTS			4
SECTION VI DISTRIBUTION OF DEFERRED FEES			6
SECTION VII DESIGNATION OF BENEFICIARY			9
SECTION VIII AMENDMENT AND TERMINATION			9
SECTION IX MISCELLANEOUS PROVISIONS			10

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AMENDED AND RESTATED COMERICA INCORPORATED

NON-EMPLOYEE DIRECTOR FEE DEFERRAL PLAN

SECTION I

PURPOSE

The purpose of the Amended and Restated Comerica Incorporated Non-Employee Director Fee Deferral Plan (the "Plan") is to allow Eligible Directors to defer their Director Fees, under the conditions provided herein, into an Investment Fund Unit Account. Eligible directors of the Corporation, directors of any Subsidiary or directors of any Advisory Board may defer all or any portion of their Director Fees into an Investment Fund Unit Account, as requested by such director.

The Plan was originally established as the "Comerica Incorporated Plan for Deferring the Payment of Director's Fees." In 1997, such plan was amended and restated as the "Comerica Incorporated Director Fee Deferral Plan." Then on May 21, 1999, the plan was divided into two plans, one of which became the "Comerica Incorporated 1999 Discretionary Director Fee Deferral Plan," and which was subsequently amended and restated on November 26, 2002 as the "Comerica Incorporated Director Fee Deferral Plan," and on January 27, 2004 as the "Comerica Incorporated Non-Employee Director Fee Deferral Plan".¹ Subsequently, on November 18, 2008, the Plan was amended and restated, effective December 31, 2008, to accurately reflect its administration and to comply with the requirements of Code Section 409A. The Plan was again amended on June 16, 2010, effective as of January 1, 2010, was further amended and restated on January 27, 2015 and was again amended and restated as of July 1, 2020.

SECTION II

DEFINITIONS

The following words and phrases, wherever capitalized, shall have the following meanings respectively:

A. "Advisory Board" means a special board of directors appointed to advise a Subsidiary or unit of the Corporation.

B. "Aggregated Plan" means all agreements methods, programs, and other arrangements sponsored by the Corporation that would be aggregated with this Plan under Section 1.409A-1(c) of the Regulations.

¹ The second plan which resulted from the division was named the "Comerica Incorporated 1999 Common Stock Director Fee Deferral Plan," which was amended and restated on November 26, 2002 as the "Comerica Incorporated Common Stock Director Fee Deferral Plan" and was further amended and restated on January 27, 2004 as the "Amended and Restated Comerica Incorporated Common Stock Non-Employee Director Fee Deferral Plan" and again amended and restated, effective November 18, 2008.

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C. "Beneficiary(ies)" means such individual(s) or entity(ies) designated on the most recent valid Beneficiary Designation Form that the Participant has properly submitted to the Corporation or in accordance with Section VII of this Plan, if there is no valid Beneficiary designation.

D. "Beneficiary Designation Form" is the form used to designate the Participant's Beneficiary(ies), as modified by the Plan Administrator or the Committee from time to time.

E. "Code" means the Internal Revenue Code of 1986, as amended, or any successor statute.

F. "Committee" means the Governance, Compensation and Nominating Committee of the Board of Directors of the Corporation, or any successor committee duly authorized by the Board of Directors of the Corporation.

G. "Corporation" means Comerica Incorporated, a Delaware corporation, and its successors and assigns.

H. "Deferral Election Form" is the form used to defer the payment of unearned Director Fees timely submitted by a Participant, as modified by the Plan Administrator or the Committee from time to time.

I. "Director Fees" means the fees paid in connection with the performance of duties as an Eligible Director, including attendance fees, retainer fees and fees for serving as chair or vice-chair of any committee of the board of the Corporation or its Subsidiaries or an Advisory Board.

J. "Eligible Director" means a director of the Corporation, a Subsidiary or Advisory Board who is not an employee of the Corporation or any Subsidiary.

K. "Investment Fund Unit" means a unit equivalent to a fund share that is maintained for the benefit of a Participant in an Investment Fund Unit Account of such Participant.

L. "Investment Fund Unit Account" means an account established under Section V of this Plan, solely for bookkeeping purposes, in the name of each Participant to record those Director Fees that have been deferred to such account and the earnings thereon.

M. "Participant" means an Eligible Director for whom an Investment Fund Unit Account is maintained under the Plan.

N. "Plan" means the Amended and Restated Comerica Incorporated Non-Employee Director Fee Deferral Plan, the provisions of which are set forth herein, as it may be further amended and restated from time to time.

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O. "Plan Administrator" means one or more individuals appointed by the Committee to handle the day-to-day administration of the Plan.

P. "Regulations" means the Treasury Regulations promulgated under the Code.

Q. "Retirement" means the date of the next annual shareholder's meeting of the Corporation immediately following the Director's 72nd birthday.

R. "Subsidiary" means any corporation, partnership or other entity, a majority of whose stock or interests is or are owned by the Corporation.

S. "Unforeseeable Emergency" means a severe financial hardship to the Participant resulting from a sudden and unexpected illness or accident of the Participant, the Participant's spouse, or a dependent (as defined in Code Section 152, without regard to Section 152(b)(1), (b)(2), and (d)(1)(B)) of the Participant; loss of the Participant's property due to casualty (including the need to rebuild a home following damage to a home not otherwise covered by insurance, for example not as a result of a natural disaster); or other similar extraordinary and unforeseeable circumstances arising as a result of events beyond the control of the Participant. This definition shall be construed in a manner that is consistent with Code Section 409A and the Regulations promulgated thereunder.

SECTION III

ELIGIBILITY

Each Eligible Director shall be eligible to participate in the Plan.

SECTION IV

PROCEDURES RELATING TO DEFERRALS

A. Deferral of Director Fees. Eligible Directors may defer any portion (0% - 100%) of their Director Fees under this Plan.

1. Deferral Period. Director Fees may be deferred pursuant to this Section IV(A) for the period specified by the Eligible Director or Participant in a Deferral Election Form. The minimum deferral period for Director Fees deferred pursuant to this Section IV(A) shall be the lesser of the number of years remaining before Retirement, as defined in Section II(R), or five (5) years from the date of service for which the Director Fees became payable, notwithstanding the deferral election under this Plan. With respect to a Director whose service commences during a calendar year, the deferral period with respect to Director Fees earned during such year shall include the full calendar year in which his or her services commence.

2. Deferred Director Fees. Once Director Fees are deferred under this Plan, the Participant may not receive distributions of such deferred amounts, except in accordance with Section VI of this Plan.

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B. Deferral Procedures. Any Eligible Director wishing to defer Director Fees must submit a Deferral Election Form to the Plan Administrator within the time frame permitted by the Plan Administrator, which shall in no event be later than the last business date preceding the calendar year during which the Director Fees are to be earned. However, any newly-appointed or newly-elected director may submit a Deferral Election Form with respect to unearned Director Fees within thirty (30) days of his or her appointment or election. A deferral election pursuant to this Plan may cover all or a portion (0% - 100%) of the Director Fees which may be deferred, and shall designate into which investment fund and in what proportions the Director Fees should be recorded.

In the event a Participant does not indicate an appropriate minimum deferral period in a Deferral Election Form, such Participant's applicable Director Fees shall be deferred for a period of five (5) years from the date of service for which the Director Fees became payable, notwithstanding the deferral election under this Plan. If a Participant does not indicate the method of deferral, such Director Fees shall be paid out in a single lump sum at the end of the deferral period.

C. Modifications/Irrevocability. The Participant's deferral election shall remain in effect with respect to all unearned Director Fees unless the Participant modifies such election prior to the date on which the election becomes irrevocable with respect to such fees. Except to the extent expressly provided under the Plan or permitted under Code Section 409A and the Regulations promulgated thereunder, the provisions of the Deferral Election Form relating to an election to defer Director Fees and the selection of the deferral period and manner of payment of the deferrals shall be irrevocable as of the last date on which such Deferral Election Form may be submitted in accordance with Article IV(B). If a director has submitted a Deferral Election Form relating to Director Fees to be earned in the future, he or she may modify or cancel such election by submitting a new Deferral Election Form at any time prior to the date on which such election is irrevocable with respect to such fees.

D. Subsequent Elections. A Director is not permitted to make a subsequent election with respect to the timing or form of payment of any Director Fees deferred under this Plan pursuant to a Deferral Election Form that has become irrevocable in accordance with Article IV(C)above.

SECTION V

CREDITING AND ADJUSTING ACCOUNTS

A. Value of Investment Fund Unit Account. Director Fees which have been deferred under this Plan, and deemed earnings thereon, shall be credited to Investment Fund Unit Accounts created by and recorded on the books of the Corporation from time to time. Each Investment Fund Unit Account shall be adjusted as follows:

1. Each Participant's Investment Fund Unit Account shall be deemed to be invested in one or more of the investment funds offered for investment and designated by such Participant in the manner determined by the Plan

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Administrator. No Participant shall have any right to vote any shares of the investment funds held in the rabbi trust or otherwise owned by the Corporation in respect of its obligations hereunder.

The deemed purchase price for Investment Fund Units under this Plan shall be based upon the closing price for the corresponding investment fund shares on the exchange on which the relevant investment fund is listed or the market on which such investment fund is traded on the day that the Director Fees would have otherwise been paid to the Participant had they not been deferred.

2. Participant's Investment Fund Unit Account shall be charged each business day with any distributions made on such day. Such Investment Fund Unit Account shall also be credited with deemed earnings, gains and losses each business day, using the closing price for the designated investment fund on the exchange on which such investment fund is listed or the market on which such investment fund is traded as of the most recent prior trading day.  Dividends shall be deemed to be reinvested in like investment funds and shall be credited at the time actual dividends are paid, with the number of Investment Fund Units attributable to a dividend being calculated by dividing the dollar amount of the dividend by the closing price of a share of the designated investment fund on the dividend payment date; provided that if the Corporation, in its sole and absolute discretion, has established a rabbi trust for its own benefit to fund the Corporation's obligations under this Plan, or otherwise purchased shares to be held in its own name, or for its own account (as general assets of the Corporation), that may be used for meeting its obligations to provide benefits under this Plan, then dividends shall be credited based on the purchase price(s) for the investment fund shares, as determined under Section V.A.1. above. Finally, a Participant's Investment Fund Unit Account shall be credited with the amount, if any, of Director Fees deferred and designated to be credited to such account during each quarter, or on a more frequent basis if deemed appropriate by the Committee.

B. Reallocation of Existing Account Balances. Each Participant may reallocate all or a portion of his or her existing Investment Fund Unit Account to an alternate investment fund or funds, as an investment option with respect to existing deferred Director Fees, in the manner designated by the Corporation for this purpose. To the extent the Corporation has purchased investment fund shares on the open market that may be used for meeting its obligations to provide benefits under this Plan, whether such shares are held in a rabbi trust established in the Corporation's sole and absolute discretion for its own benefit to fund the Corporation's obligations under this Plan or otherwise held in the Corporation's own name or for its own account (as general assets of the Corporation), (1) the Plan Administrator may delay any reallocation request because of a trading blackout period or any other trading restriction which may be imposed on the Corporation, whether voluntary or involuntary, and (2) no transfers between investment options will be allowed if prohibited by the rules applicable to the particular investment fund from or to which a transfer is to be made or by rules adopted by the Plan Administrator and communicated to the Participants.

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C. Reallocation of Future Deferral Elections. Each Participant may reallocate all or a portion of his or her Investment Fund Unit Account to change prospectively the percentage(s) of an investment and/or designate an alternate investment fund or funds, as an investment option with respect to future deferred Director Fees in the manner designated by the Corporation for this purpose. To the extent the Corporation purchases investment fund shares on the open market that may be used for meeting its obligations to provide benefits under this Plan, whether such shares are held in a rabbi trust established in the Corporation's sole and absolute discretion for its own benefit to fund the Corporation's obligations under this Plan or otherwise held in the Corporation's own name or for its own account (as general assets of the Corporation), the Plan Administrator may delay any reallocation request because of a trading blackout period or any other trading restriction which may be imposed on the Corporation, whether voluntary or involuntary.

SECTION VI

DISTRIBUTION OF DEFERRED FEES

A. Time and Manner. Subject to the provisions of Section IV of this Plan, distribution of the Participant's Investment Fund Unit Account shall be made in cash at such time and in such manner, i.e., a lump sum or installments, as the Participant has specified in the Deferral Election Form.

1. Lump Sum Distributions. If the Participant elects to receive a lump sum distribution, the Corporation shall make a single payment of the amounts subject to that election in the applicable Deferral Election Form in the calendar year following the calendar year in which the deferral period ends. If a Participant fails to indicate a payment method, the Participant shall be deemed to have elected a lump sum distribution.

2. Installment Distributions. If the Participant elects to receive installment distributions, the Corporation shall make installment payments of the amounts subject to that election in the applicable Deferral Election Form over a period of time as specified by the Participant on the applicable Deferral Election Form. Installment payments shall commence in the calendar year following the calendar year in which the deferral period ends. A Participant may choose an applicable installment period from the options designated by the Corporation on the Deferral Election Form, which shall not exceed ten (10) years from the date of distribution of the first installment. The amount of each installment payment shall be determined by multiplying the amounts subject to such Deferral Election Form on the date the installment is scheduled to be paid by a fraction, the numerator of which is one and the denominator of which is the number of unpaid installments remaining at such time.

a. Less than $10,000. If, at the time an installment distribution of an Investment Fund Unit Account is scheduled to commence, the fair market value of all the Investment Fund Units in such Investment Fund Unit Account does not exceed $10,000, notwithstanding an election by the

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Participant that such account be distributed in installments, the balance of such account shall be distributed to the Participant in a lump sum, in cash.

B. Death. Notwithstanding any other provision of the Plan, upon the death of a Participant, the remaining balance of his or her Investment Fund Unit Account shall be distributed in one lump sum to the Participant's Beneficiary(ies) within ninety (90) days after the date of the Participant's death.

C. Hardship Distributions. In the event of an Unforeseeable Emergency prior to distribution of the entire balance of the Participant's Investment Fund Unit Account, the Committee may, in its sole discretion, direct a distribution to the Participant, within ninety (90) days following such Unforeseeable Emergency, in an amount reasonably necessary, in the judgment of the Committee, to satisfy the financial hardship occasioned by the Unforeseeable Emergency, plus amounts necessary to pay any Federal, state, local or foreign income taxes anticipated as a result of the distribution or cancel a future deferral election with respect to the amount reasonably necessary, in the judgment of the Committee, to alleviate such financial hardship. However, no distribution will be made on account of an Unforeseeable Emergency to the extent that such emergency is or may be relieved through reimbursement or compensation from insurance or otherwise, by liquidation of the Participant's assets, to the extent the liquidation of such assets would not cause severe financial hardship, or by cessation of deferrals under the Plan. Any Participant desiring a distribution under the Plan on account of an Unforeseeable Emergency shall submit to the Committee a written request for such distribution which sets forth in reasonable detail the Unforeseeable Emergency which would cause the Participant severe financial hardship, and the amount which the Participant believes to be necessary to alleviate the financial hardship. Any Participant who receives a hardship distribution shall have his deferral election cancelled hereunder and shall not again be eligible to submit a deferral election until the next enrollment period after the calendar year in which the hardship distribution is made.

D. Distribution in the Event of Income Inclusion Under Code Section 409A. If any portion of a Participant's Investment Fund Unit Account is required to be included in income by the Participant prior to receipt due to a failure of this Plan or any Aggregated Plan to comply with the requirements of Code Section 409A and the Regulations, the Committee may determine that such Participant shall receive a distribution from the Plan in an amount equal to the lesser of: (i) the portion of the Participant's Investment Fund Unit Account required to be included in income as a result of the failure of the Plan or any Aggregated Plan to comply with the requirements of Code Section 409A and the Regulations, or (ii) the balance of the Participant's Investment Fund Unit Account.

E. Delay for Payments in Violation of Federal Securities Laws or Other Applicable Law. In the event the Corporation reasonably anticipates that the payment of benefits as specified hereunder would violate Federal securities laws or other applicable law, the Committee may delay the payment under this Section VI until the earliest date at which the Corporation reasonably anticipates that making of such payment would not cause such violation.

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F. Delay for Insolvency or Compelling Business Reasons. In the event the Corporation determines that the making of any payment of benefits on the date specified hereunder would jeopardize the ability of the Corporation to continue as a going concern, the Committee may delay the payment of benefits under this Section VI until the first calendar year in which the Corporation notifies the Committee that the payment of benefits would not have such effect.

G. Administrative Delay in Payment. The payment of benefits hereunder shall begin at the date specified in accordance with the provisions of the foregoing paragraphs of this Section VI; provided that, in the case of administrative necessity, the payment of such benefits may be delayed up to the later of the last day of the calendar year in which payment would otherwise be made or the 15th day of the third calendar month following the date on which payment would otherwise be made. Further, if, as a result of events beyond the control of the Participant (or following the Participant's death, the Participant's Beneficiary), it is not administratively practicable for the Plan Administrator to calculate the amount of benefits due to Participant as of the date on which payment would otherwise be made, the payment may be delayed until the first calendar year in which calculation of the amount is administratively practicable.

H. No Participant Election. Notwithstanding the foregoing provisions, if the period during which payment of benefits hereunder will be made occurs, or will occur, in two calendar years, the Participant shall not be permitted to elect the calendar year in which the payment shall be made.

SECTION VII

DESIGNATION OF BENEFICIARY

Upon becoming a Participant of the Plan, each director shall submit to the Plan Administrator a Beneficiary Designation Form designating one or more Beneficiaries to whom distributions otherwise due the Participant, shall be made in a lump sum payment in the event of the Participant's death before distribution of the Participant's Investment Fund Unit Account has been completed. A Beneficiary Designation Form will be effective only if it is validly submitted by the Participant to the Plan Administrator before the Participant's death. Any subsequent Beneficiary Designation Form properly submitted will supersede any previous Beneficiary Designation Form so submitted. If a Participant designates a spouse as a Beneficiary, such designation shall automatically terminate and be of no effect following the divorce of the Participant and such individual, unless ratified in writing post-divorce.

If the primary Beneficiary shall predecease the Participant, or the primary Beneficiary and the Participant die in a common disaster under such circumstances that it is impossible to determine who survived the other, the portion of the Investment Fund Unit Account that remains undistributed at the time of the Participant's death shall be distributed to the alternate Beneficiary(ies) who survive(s) the Participant in the manner set forth in the Beneficiary Designation Form. If there are no alternate Beneficiaries living or in existence at the date of the Participant's death, or if the Participant has not submitted a valid Beneficiary Designation Form to the Corporation, the balance of the

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account shall be paid in a lump sum distribution to the legal representative for the benefit of the Participant's estate.

SECTION VIII

AMENDMENT AND TERMINATION

A. Amendment of Plan. This Plan may be amended at any time in the sole discretion of the Board or Committee, by a written resolution, to the extent that such amendment complies with applicable laws including Code Section 409A and the Regulations promulgated thereunder. No such amendment shall affect the time of distribution of any of the Incentive Awards earned prior to the time of such amendment except as the Committee may determine to be necessary to carry out the purpose of the Plan.

B. Termination of Plan. The Plan may be terminated at any time in the sole discretion of the Board or Committee by a written resolution of its members. Following the termination of the Plan, the Investment Fund Unit Accounts may be liquidated in accordance with one of the following:

1. the termination and liquidation of the Plan within twelve (12) months of a complete dissolution of the Corporation taxed under Section 331 of the Code or with the approval of a bankruptcy court pursuant to 11 U.S.C. § 503(b)(1)(A); provided that the amounts deferred under this Plan are included in the Participants' gross incomes in the latest of the following years (or, if earlier, the taxable year in which the amount is actually or constructively received): (i) the calendar year in which the Plan is terminated; (ii) the first calendar year in which the amount is no longer subject to a substantial risk of forfeiture; or (iii) the first calendar year in which the payment is administratively practicable.

2. the termination and liquidation of the Plan pursuant to irrevocable action taken by the Committee or the Corporation within the thirty (30) days preceding or the twelve (12) months following a change in control event (as such term is defined in Section 1.409A-3(i)(5) of the Regulations; provided that all Aggregated Plans are terminated and liquidated with respect to each Participant that experienced the change in control, so that under the terms of the termination and liquidation, all such Participants are required to receive all amounts of deferred compensation under this Plan and any other Aggregated Plans within twelve (12) months of the date the Committee or the Corporation irrevocably takes all necessary action to terminate and liquidate this Plan and the date the Committee (or the Corporation, as the case may be) irrevocably takes all necessary action to terminate and liquidate such other Aggregated Plans;

3. the termination and liquidation of the Plan, provided that: (i) the termination and liquidation does not occur proximate to a downturn in the Corporation's financial health; (ii) the Committee or the Corporation, as the case may be, terminates and liquidates all Aggregated Plans; (iii) no payments in liquidation of this Plan are made within twelve (12) months of the date the

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Committee or the Corporation irrevocably takes all necessary action to terminate and liquidate this Plan, other than payments that would be payable under the terms of this Plan if the action to terminate and liquidate this Plan had not occurred; (iv) all payments are made within twenty four (24) months of the date on which the Committee or the Corporation irrevocably takes all action necessary to terminate and liquidate this Plan; and (iv) the Corporation does not adopt a new Aggregated Plan at any time within three (3) years following the date on which the Committee or the Corporation irrevocably takes all action necessary to terminate and liquidate the Plan.

SECTION IX

MISCELLANEOUS PROVISIONS

A. Participant Consent. By electing to defer compensation pursuant to the Plan, Participants shall be deemed conclusively to have accepted and consented to all terms of the Plan as amended from time to time, and all actions or decisions made or to be made by the Corporation, the Board of Directors, the Committee or the Plan Administrator with regard to the Plan. Such terms and consent shall also apply to, and be binding upon, the Beneficiaries, distributees and personal representatives and other successors in interest of each Participant.

B. Notice. Any election made, or notice given by a Participant pursuant to the Plan shall be in writing to the Committee, or to such representative as may be designated by the Committee for such purpose. Notice shall be deemed to have been made or given on the date received by the Committee or its designated representative.

C. Competency. If the Committee determines that any person to whom a payment is due hereunder is a minor, or is adjudicated incompetent by reason of physical or mental disability, the Committee shall have the power to cause the payments becoming due to such person to be made to the legal guardian for the benefit of the minor or incompetent, without responsibility of the Corporation or the Committee to see to the application of such payment, unless prior to such payment claim is made therefore by a duly appointed legal representative. Payments made pursuant to such power shall operate as a complete discharge of the Corporation, the Board of Directors and the Committee.

D. Nonalienation of Benefits. Neither the Participant nor any Beneficiary designated by him or her shall have any right to alienate, assign, or encumber any benefits that are or may be distributed hereunder, nor may any such amount be subject to attachment, garnishment, levy, execution or other legal or equitable process for the debts, contracts, liabilities, engagements or acts of any Participant or Beneficiary.

E. Administration of Plan. Full power and authority to construe, interpret, and administer the Plan shall be vested in the Committee. To the extent permitted by law, the Committee may delegate any authority it possesses to the Plan Administrator. To

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the extent the Committee has delegated authority concerning a matter to the Plan Administrator, any reference in the Plan to the "Committee" insofar as it pertains to such matter, shall refer likewise to the Plan Administrator. Decisions of the Committee shall be final, conclusive, and binding upon all parties.

F. Fees and Expenses of Administration. If the Committee so determines, reasonable trustee's fees (if applicable) and reasonable out-of-pocket expenses of administering the Plan may be ratably deducted (using average balances) on an annual basis from Investment Fund Unit Accounts. In the event the Corporation, in its sole and absolute discretion, has established a rabbi trust for its own benefit to fund the Corporation's obligations under this Plan, or otherwise purchased shares to be held in its own name, or for its own account (as general assets of the Corporation), that may be used for meeting its obligations to provide benefits under this Plan and fees of any kind, including, without limitation, redemption fees, are assessed or imposed thereto by an investment fund company in connection with any purchase or sale, including, without limitation, a Participant's early trading activity, such fees shall be charged to the applicable Participant's Investment Fund Unit Account.

G. Effective Date. The terms of this Plan shall apply to all Director Fees deferred under this Plan or one of its predecessors on and after July 1, 2020, except to the extent that retroactive application would adversely affect the rights of a Participant or Beneficiary to the amounts in the applicable Investment Fund Unit Account at the time of the adoption of this amendment and restatement of the Plan.

H. Statements to Participants. Statements will be provided to Participants under the Plan on at least an annual basis.

I. Nonforfeitability of Participant Accounts. Each Participant shall be fully vested in his or her Investment Fund Unit Account, and the right to receive the amounts in the Investment Fund Unit Account shall be nonforfeitable.

J. Successors Bound. The contractual agreement between the Corporation and each Participant resulting from the execution of a Deferral Election Form shall be binding upon and inure to the benefit of the Corporation, its successors and assigns, and to the Participant and to the Participant's beneficiaries, heirs, executors, administrators and other legal representatives.

K. Governing Law and Rules of Construction. This Plan shall be governed in all respects, whether as to construction, validity or otherwise, by the laws of the State of Delaware unless preempted by Federal law.

L. Compliance & Severability. It is the Corporation's intent to comply with all applicable tax and other laws, including Code Section 409A and the Regulations promulgated thereunder, so that all rights under the Plan will be limited as necessary in the judgment of the Committee to conform therewith. Therefore, consistent with the effectuation of the purposes hereof, each provision of this Plan shall be treated as severable, to the end that, if any one or more provisions shall be adjudged or declared

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illegal, invalid or unenforceable, this Plan shall be interpreted, and shall remain in full force and effect, as though such provision or provisions had never been contained herein. It is the intention of the Corporation that the Plan established hereunder be "unfunded" for income tax purposes, whether or not the Corporation establishes a rabbi trust, and the provisions hereof shall be construed in a manner to carry out that intention.

M. Ownership of Deferred Director Fees and Continued Director Status. Title to and beneficial ownership of any assets, of whatever nature, which may be allocated by the Corporation to any Investment Fund Unit Account in the name of any Participant shall at all times remain with the Corporation and its Subsidiaries, and no Participant or Beneficiary shall have any property interest whatsoever in any specific assets of the Corporation or its Subsidiaries by reason of the establishment of the Plan. The rights of each Participant and Beneficiary hereunder shall be limited to enforcing the unfunded, unsecured promise of the Corporation and its Subsidiaries to pay benefits under the Plan, and the status of any Participant or Beneficiary shall be that of an unsecured general creditor of the Corporation and its Subsidiaries. Neither the establishment of the Plan nor the distribution of any benefits hereunder or any action of the Corporation, its Board of Directors or any committee thereto, shall be held or construed to confer upon any person the legal right to remain a director of the Corporation or any Subsidiary or any Advisory Board beyond the term for which he or she was elected or appointed to the board(s) on which he or she serves.

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Exhibit 10.12

Governance, Compensation and Nominating Committee Approval: June 24, 2020

Board Approval: July 28, 2020

AMENDED AND RESTATED COMERICA INCORPORATED

COMMON STOCK NON-EMPLOYEE DIRECTOR FEE DEFERRAL PLAN

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AMENDED AND RESTATED COMERICA INCORPORATED

COMMON STOCK NON-EMPLOYEE DIRECTOR FEE DEFERRAL PLAN

TABLE OF CONTENTS

SECTION I  PURPOSE.............................................................			1
SECTION II  DEFINITIONS........................................................			1
SECTION III ELIGIBILITY...........................................................			3
SECTION IV  PROCEDURES RELATING TO DEFERRALS......			3
SECTION V  CREDITING AND ADJUSTING ACCOUNTS........			4
SECTION VI  DISTRIBUTION OF DEFERRED FEES................			6
SECTION VII  DESIGNATION OF BENEFICIARY........................			8
SECTION VIII  AMENDMENT AND TERMINATION......................			9
SECTION IX  MISCELLANEOUS PROVISIONS.........................			10

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AMENDED AND RESTATED COMERICA INCORPORATED

COMMON STOCK NON-EMPLOYEE DIRECTOR FEE DEFERRAL PLAN

SECTION I

PURPOSE

The purpose of the Amended and Restated Comerica Incorporated Common Stock Non-Employee Director Fee Deferral Plan (the "Common Stock Plan") is to allow Eligible Directors to defer their Director Fees, under the conditions provided herein, into a Corporation Stock Unit Account. Eligible Directors may defer all or any portion of their Director Fees into a Corporation Stock Unit Account as requested by such director.

The Common Stock Plan was originally established as the "Comerica Incorporated Plan for Deferring the Payment of Director's Fees." In 1997, such plan was amended and restated as the "Comerica Incorporated Director Fee Deferral Plan." Then on May 21, 1999, the plan was divided into two plans, one of which became the "Comerica Incorporated 1999 Common Stock Director Fee Deferral Plan," and which was subsequently amended and restated on November 26, 2002 as the "Comerica Incorporated Common Stock Director Fee Deferral Plan," and on January 27, 2004 as the "Amended and Restated Comerica Incorporated Common Stock Non-Employee Director Fee Deferral Plan". Subsequently, on November 18, 2008, the Plan was amended and restated, effective December 31, 2008, to accurately reflect its administration and to comply with the requirements of Code Section 409A. The Plan was again amended on June 16, 2010, effective as of January 1, 2010, was further amended and restated on January 27, 2015 and was again amended and restated as of July 1, 2020.

SECTION II

DEFINITIONS

The following words and phrases, wherever capitalized, shall have the following meanings respectively:

i."Advisory Board" means a special board of directors appointed to advise a Subsidiary or unit of the Corporation.

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B. "Aggregated Plan" means all agreements methods, programs, and other arrangements sponsored by the Corporation that would be aggregated with the Common Stock Plan under Section 1.409A-1(c) of the Regulations.

C. "Beneficiary(ies)" means such individual(s) or entity(ies) designated on the most recent valid Beneficiary Designation Form that the Participant has properly submitted to the Corporation, or in accordance with Section VII of this Common Stock Plan, if there is no valid Beneficiary designation.

D. "Beneficiary Designation Form" is the form used to designate the Participant's Beneficiary(ies), as modified by the Plan Administrator or the Committee from time to time.

E. "Code" means the Internal Revenue Code of 1986, as amended, or any successor statute.

F. "Committee" means the Governance, Compensation and Nominating Committee of the Board of Directors of the Corporation, or any successor committee duly authorized by the Board of Directors of the Corporation.

G. "Common Stock" means the common stock of the Corporation, par value $5.00 per share.

H. "Common Stock Plan" means the Amended and Restated Comerica Incorporated Common Stock Non-Employee Director Fee Deferral Plan, the provisions of which are set forth herein, as it may be further amended and restated from time to time.

I. "Corporation" means Comerica Incorporated, a Delaware corporation, and its successors and assigns.

J. "Corporation Stock Unit Account" means an account established under Section V of this Common Stock Plan, solely for bookkeeping purposes, in the name of each Participant to record those Director Fees that are deferred under this Common Stock Plan on the Participant's behalf and the earnings and dividends thereon.

K. "Deferral Election Form" is the form used to defer the payment of unearned Director Fees timely submitted by a Participant, as modified by the Plan Administrator or the Committee from time to time.

L. "Director Fees" means the fees paid in connection with the performance of duties as an Eligible Director, including attendance fees, retainer fees and fees for serving as chair or vice-chair of any committee of the board of the Corporation or its Subsidiaries or an Advisory Board.

M. "Eligible Director" means a director of the Corporation, a Subsidiary or Advisory Board who is not an employee of the Corporation or any Subsidiary.

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N. "Participant" means an Eligible Director for whom a Corporation Stock Unit Account is maintained under the Common Stock Plan.

O. "Plan Administrator" means one or more individuals appointed by the Committee to handle the day-to-day administration of the Common Stock Plan.

P. "Regulations" means the Treasury Regulations promulgated under the Code.

Q. "Retirement" means the date of the next annual shareholder's meeting of the Corporation immediately following the Director's 72nd birthday.

R. "Stock Unit" means a unit equivalent to a share of Common Stock that is maintained for the benefit of a Participant in the Corporation Stock Unit Account of such Participant.

S. "Subsidiary" means any corporation, partnership or other entity, a majority of whose stock or interests is or are owned by the Corporation.

T. "Unforeseeable Emergency" means a severe financial hardship to the Participant resulting from a sudden and unexpected illness or accident of the Participant, the Participant's spouse, or a dependent (as defined in Code Section 152, without regard to Section 152(b)(1), (b)(2), and (d)(1)(B)) of the Participant; loss of the Participant's property due to casualty (including the need to rebuild a home following damage to a home not otherwise covered by insurance, for example not as a result of a natural disaster); or other similar extraordinary and unforeseeable circumstances arising as a result of events beyond the control of the Participant. This definition shall be construed in a manner that is consistent with Code Section 409A and the Regulations promulgated thereunder.

SECTION III

ELIGIBILITY

Each Eligible Director shall be eligible to participate in the Plan.

SECTION IV

PROCEDURES RELATING TO DEFERRALS

A. Deferral of Director Fees. Eligible Directors may defer any portion (0% – 100%) of their Director Fees under this Common Stock Plan.

1. Deferral Period. Director Fees may be deferred pursuant to this Section IV(A) for the period specified by the Eligible Director or Participant in a Deferral Election Form. The minimum deferral period for Director Fees deferred pursuant to this Section IV(A) shall be the lesser of the number of years remaining before Retirement, as defined in Section II(R), or five (5) years from the date of service for which the Director Fees became payable, notwithstanding the deferral election under this Common Stock Plan. With respect to a Director

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whose service commences during a calendar year, the deferral period with respect to Director Fees earned during such year shall include the full calendar year in which his or her services commence.

2. Deferred Director Fees. Once Director Fees are deferred under this Common Stock Plan, a Participant may not receive distributions of such deferred amounts, except in accordance with Section VI of this Common Stock Plan.

B. Deferral Procedures. Any Eligible Director wishing to defer Director Fees must submit a Deferral Election Form to the Plan Administrator within the time frame permitted by the Plan Administrator, which shall in no event be later than the last business date preceding the calendar year during which the Director Fees are to be earned. However, any newly-appointed or newly-elected director may submit a Deferral Election Form, with respect to unearned Director Fees, within thirty (30) days of his or her appointment or election. A deferral election pursuant to this Common Stock Plan may cover all or a portion (0% – 100%) of the Director Fees which may be deferred.

In the event a Participant does not indicate an appropriate minimum deferral period in a Deferral Election Form, such Participant's applicable Director Fees shall be deferred for a period of five (5) years from the date of service for which the Director Fees became payable, notwithstanding the deferral election under this Common Stock Plan. If a Participant does not indicate the method of deferral, such Director Fees shall be paid out in a single lump sum at the end of the deferral period.

C. Modifications/Irrevocability. The Participant's deferral election shall remain in effect with respect to all unearned Director Fees unless the Participant modifies such election prior to the date on which the election becomes irrevocable with respect to such fees. Except to the extent expressly provided under the Plan or permitted under Code Section 409A and the Regulations promulgated thereunder, the provisions of the Deferral Election Form relating to an election to defer Director Fees and the selection of the deferral period and manner of payment of the deferrals shall be irrevocable as of the last date on which such Deferral Election Form may be submitted in accordance with Article IV(B). If a director has submitted a Deferral Election Form relating to Director Fees to be earned in the future, he or she may modify or cancel such election by submitting a new Deferral Election Form at any time prior to the date on which such election is irrevocable with respect to such fees.

D. Subsequent Elections. A Director is not permitted to make a subsequent election with respect to the timing or form of payment of any Director Fees deferred under this Plan pursuant to a Deferral Election Form that has become irrevocable in accordance with Article IV(C) above.

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SECTION V

CREDITING AND ADJUSTING ACCOUNTS

A. Director Fees, which have been deferred under the Common Stock Plan, and deemed earnings thereon, shall be credited to a Corporation Stock Unit Account created by and recorded on the books of the Corporation from time to time. The Corporation Stock Unit Account shall be adjusted as follows:

1. A Participant's Corporation Stock Unit Account shall be deemed to be invested in Common Stock. In the event the Corporation, in its sole and absolute discretion, has purchased shares of Common Stock that may be used for meeting its obligations to provide benefits under this Common Stock Plan, whether such shares are held in a rabbi trust for its own benefit to fund the Corporation's obligations under this Common Stock Plan, or held in the Corporation's own name or for its own account (as general assets of the Corporation), the purchase price for the Stock Units shall be the actual price of the corresponding shares of Common Stock that the Corporation purchases on the open market, provided such purchase(s) occurs within two (2) business days of the date the Director Fees would have otherwise been paid to the director had they not been deferred.

2. In the event that the Corporation, in its sole and absolute discretion, has not purchased shares of Common Stock that may be used for meeting its obligations to provide benefits under this Common Stock Plan within the designated time frame, then the purchase price of Stock Units shall be based upon the closing price for the Common Stock on the New York Stock Exchange on the day that the Director Fees would have otherwise been paid to the director had they not been deferred.

3. To the extent the Corporation, in its sole and absolute discretion, has purchased shares of Common Stock that may be used for meeting its obligations to provide benefits under this Common Stock Plan, whether such shares are held in a rabbi trust for its own benefit to fund the Corporation's obligations under this Common Stock Plan, or held in the Corporation's own name or for its own account (as general assets of the Corporation), no Participant shall have any right to vote any shares of Common Stock held in the rabbi trust or otherwise owned by the Corporation in respect of its obligations hereunder.

4. A Participant's Corporation Stock Unit Account shall be charged each business day with any distributions made on such day. Such Corporation Stock Unit Account shall also be credited with deemed earnings, gains and losses each business day, using the closing price for Common Stock on the New York Stock Exchange as of the most recent prior trading day. Dividends shall be deemed to be reinvested in Common Stock and shall be credited at the time actual dividends are paid, with the number of Stock Units attributable to a dividend being calculated by dividing the dollar amount of the dividend by the

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closing price of the Common Stock on the dividend payment date; provided that if the Corporation, in its sole and absolute discretion, has established a rabbi trust for its own benefit to fund the Corporation's obligations under this Common Stock Plan, or otherwise purchased shares to be held in its own name, or for its own account (as general assets of the Corporation), that may be used for meeting its obligations to provide benefits under this Common Stock Plan, then dividends shall be credited based on the purchase price(s) for the shares of Common Stock determined as in Section V(A) above. Finally, a Participant's Corporation Stock Unit Account shall be credited with the amount, if any, of Director Fees deferred and designated to be credited to such account during each quarter, or on a more frequent basis if deemed appropriate by the Committee.

B. Changes in Capitalization. The shares of Common Stock in the Corporation Stock Unit Accounts shall be subject to adjustment or substitution, as determined in the sole discretion of the Board of Directors of the Corporation, in the event of any change in corporate capitalization, such as a stock split or a corporate transaction, such as any merger, consolidation, separation, including a spin off, or other distribution of stock or property of the Corporation, any reorganization (whether or not such reorganization comes within the definition of such term in Section 368 of the Code) or any partial or complete liquidation of the Corporation.

SECTION VI

DISTRIBUTION OF DEFERRED FEES

A. Time and Manner. Subject to the provisions of Section IV of this Common Stock Plan, distribution of the Participant's Corporation Stock Unit Account shall be made in Common Stock at such time and in such manner, i.e., a lump sum or installments, as the Participant has specified in the Deferral Election Form. Fractional shares of Common Stock shall be paid in cash.

1. Lump Sum Distributions. If the Participant elects to receive a lump sum distribution, the Corporation shall make a single payment of the amounts subject to that election in the applicable Deferral Election Form in the calendar year following the calendar year in which the deferral period ends. If a Participant fails to indicate a payment method, the Participant shall be deemed to have elected a lump sum distribution.

2. Installment Distributions. If the Participant elects to receive installment distributions, the Corporation shall make installment payments of the amounts subject to that election in the applicable Deferral Election Form over a period of time as specified by the Participant on the applicable Deferral Election Form. Installment distributions shall commence in the calendar year following the calendar year in which the deferral period ends. A Participant may choose an applicable installment period from the options designated by the Corporation on the Deferral Election Form, which shall not exceed ten (10) years from the date of distribution of the first installment. The number of shares of Common Stock distributable in each installment shall be determined by multiplying the

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amounts subject to the Deferral Election Form on the date the installment is scheduled to be distributed by a fraction, the numerator of which is one and the denominator of which is the number of unpaid installments remaining at such time.

a. Less than $10,000. If, at the time an installment distribution is scheduled to commence, the fair market value of the Participant's Corporation Stock Unit Account does not exceed $10,000, notwithstanding an election by the Participant that such account be distributed in installments, the Stock Units in such account shall be distributed in shares of Common Stock to the Participant in a lump sum.

B. Death. Notwithstanding any other provision of the Common Stock Plan, upon the death of a Participant, the remaining balance of his or her Corporation Stock Unit Account shall be distributed in one lump sum to the Participant's Beneficiary(ies) within ninety (90) days after the date of the Participant's death.

C. Hardship Distributions. In the event of an Unforeseeable Emergency prior to distribution of the entire balance of the Participant's Corporation Stock Unit Account, the Committee may, in its sole discretion, direct a distribution to the Participant, within ninety (90) days following such Unforeseeable Emergency, of the number of shares of Common Stock with a fair market value equal to an amount reasonably necessary, in the judgment of the Committee, to satisfy the financial hardship occasioned by the Unforeseeable Emergency, plus amounts necessary to pay any Federal, state, local or foreign income taxes anticipated as a result of the distribution or cancel a future deferral election with respect to the amount reasonably necessary, in the judgment of the Committee, to alleviate such financial hardship. However, no distribution will be made on account of an Unforeseeable Emergency to the extent that such emergency is or may be relieved through reimbursement or compensation from insurance or otherwise, by liquidation of the Participant's assets, to the extent the liquidation of such assets would not cause severe financial hardship, or by cessation of deferrals under the Plan. Any Participant desiring a distribution under the Common Stock Plan on account of an Unforeseeable Emergency shall submit to the Committee a written request for such distribution which sets forth in reasonable detail the Unforeseeable Emergency which would cause the Participant severe financial hardship, and the amount which the Participant believes to be necessary to alleviate the financial hardship. Any Participant who receives a hardship distribution shall have his deferral election cancelled hereunder and shall not again be eligible to submit a deferral election until the next enrollment period after the calendar year in which the hardship distribution is made.

D. Distribution in the Event of Income Inclusion Under Code Section 409A. If any portion of a Participant's Corporation Stock Unit Account is required to be included in income by the Participant prior to receipt due to a failure of this Common Stock Plan or any Aggregated Plan to comply with the requirements of Code Section 409A and the Regulations, the Committee may determine that such Participant shall receive a distribution from the Plan in an amount equal to the lesser of: (i) the portion of the Participant's Corporation Stock Unit Account required to be included in income as a

7

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result of the failure of the Common Stock Plan or any Aggregated Plan to comply with the requirements of Code Section 409A and the Regulations, or (ii) the balance of the Participant's Corporation Stock Unit Account.

E. Delay for Payments in Violation of Federal Securities Laws or Other Applicable Law. In the event the Corporation reasonably anticipates that the payment of benefits as specified hereunder would violate Federal securities laws or other applicable law, the Committee may delay the payment under this Section VI until the earliest date at which the Corporation reasonably anticipates that making of such payment would not cause such violation.

F. Delay for Insolvency or Compelling Business Reasons. In the event the Corporation determines that the making of any payment of benefits on the date specified hereunder would jeopardize the ability of the Corporation to continue as a going concern, the Committee may delay the payment of benefits under this Section VI until the first calendar year in which the Corporation notifies the Committee that the payment of benefits would not have such effect.

G. Administrative Delay in Payment. The payment of benefits hereunder shall begin at the date specified in accordance with the provisions of the foregoing paragraphs of this Section VI; provided that, in the case of administrative necessity, the payment of such benefits may be delayed up to the later of the last day of the calendar year in which payment would otherwise be made or the 15th day of the third calendar month following the date on which payment would otherwise be made. Further, if, as a result of events beyond the control of the Participant (or following the Participant's death, the Participant's Beneficiary), it is not administratively practicable for the Plan Administrator to calculate the amount of benefits due to Participant as of the date on which payment would otherwise be made, the payment may be delayed until the first calendar year in which calculation of the amount is administratively practicable.

H. No Participant Election. Notwithstanding the foregoing provisions, if the period during which payment of benefits hereunder will be made occurs, or will occur, in two calendar years, the Participant shall not be permitted to elect the calendar year in which the payment shall be made.

SECTION VII

DESIGNATION OF BENEFICIARY

Upon becoming a Participant of the Common Stock Plan, each director shall submit to the Plan Administrator a Beneficiary Designation Form designating one or more Beneficiaries to whom distributions otherwise due the Participant shall be made in a lump sum payment in the event of the Participant's death before distribution of the Participant's Corporation Stock Unit Account has been completed. A Beneficiary Designation Form will be effective only if it is validly submitted by the Participant to the Plan Administrator before the Participant's death. Any subsequent Beneficiary Designation Form properly submitted will supersede any previous Beneficiary Designation Form so submitted. If a Participant designates a spouse as a Beneficiary,

8

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such designation shall automatically terminate and be of no effect following the divorce of the Participant and such individual, unless ratified in writing post-divorce.

If the primary Beneficiary shall predecease the Participant or the primary Beneficiary and the Participant die in a common disaster under such circumstances that it is impossible to determine who survived the other, the undistributed Stock Units in the Participant's Corporation Stock Unit Account remaining at the time of the Participant's death shall be distributed in shares to the alternate Beneficiary(ies) who survive(s) the Participant in the manner set forth in the Beneficiary Designation Form. If there are no alternate Beneficiaries living or in existence at the date of the Participant's death, or if the Participant has not submitted a valid Beneficiary Designation Form to the Corporation, the remaining Stock Units in the Participant's Corporation Stock Unit Account shall be distributed in shares in a single distribution to the legal representative for the benefit of the Participant's estate.

SECTION VIII

AMENDMENT AND TERMINATION

A. Amendment of Plan. The Common Stock Plan may be amended at any time in the sole discretion of the Committee or the Board, by written resolution, to the extent that such amendment complies with applicable laws including Code Section 409A and the Regulations promulgated thereunder. No such amendment shall affect the time of distribution of any of the Incentive Awards earned prior to the time of such amendment except as the Committee may determine to be necessary to carry out the purpose of the Common Stock Plan.

B. Termination of Plan. The Common Stock Plan may be terminated at any time in the sole discretion of the Board or Committee by a written resolution of its members. Following the termination of the Common Stock Plan, the Corporation Stock Unit Accounts may be liquidated in accordance with one of the following:

1. the termination and liquidation of the Common Stock Plan within twelve (12) months of a complete dissolution of the Corporation taxed under Section 331 of the Code or with the approval of a bankruptcy court pursuant to 11 U.S.C. § 503(b)(1)(A); provided that the amounts deferred under the Common Stock Plan are included in the Participants' gross incomes in the latest of the following years (or, if earlier, the taxable year in which the amount is actually or constructively received): (i) the calendar year in which the Common Stock Plan is terminated; (ii) the first calendar year in which the amount is no longer subject to a substantial risk of forfeiture; or (iii) the first calendar year in which the payment is administratively practicable.

2. the termination and liquidation of the Common Stock Plan pursuant to irrevocable action taken by the Committee or the Corporation within the thirty (30) days preceding or the twelve (12) months following a change in control event (as such term is defined in Section 1.409A-3(i)(5) of the Regulations; provided that all Aggregated Plans are terminated and liquidated with respect to

9

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each Participant that experienced the change in control, so that under the terms of the termination and liquidation, all such Participants are required to receive all amounts of deferred compensation under this Plan and any other Aggregated Plans within twelve (12) months of the date the Committee or the Corporation irrevocably takes all necessary action to terminate and liquidate this Plan and the Committee or the Corporation, as the case may be, irrevocably takes all necessary action to terminate and liquidate such other Aggregated Plans;

3. the termination and liquidation of the Common Stock Plan, provided that: (i) the termination and liquidation does not occur proximate to a downturn in the Corporation's financial health; (ii) the Committee or the Corporation, as the case may be, terminates and liquidates all Aggregated Plans; (iii) no payments in liquidation of the Common Stock Plan are made within twelve (12) months of the date the Committee or the Corporation irrevocably takes all necessary action to terminate and liquidate the Common Stock Plan, other than payments that would be payable under the terms of the Common Stock Plan if the action to terminate and liquidate the Common Stock Plan had not occurred; (iv) all payments are made within twenty four (24) months of the date on which the Committee or the Corporation irrevocably takes all action necessary to terminate and liquidate the Common Stock Plan; and (v) the Corporation does not adopt a new Aggregated Plan at any time within three (3) years following the date on which the Committee or the Corporation irrevocably takes all action necessary to terminate and liquidate the Common Stock Plan.

SECTION IX

MISCELLANEOUS PROVISIONS

A. Participant Consent. By electing to defer compensation pursuant to the Common Stock Plan, Participants shall be deemed conclusively to have accepted and consented to all terms of the Common Stock Plan, as amended from time to time, and all actions or decisions made or to be made by the Corporation, the Board of Directors, the Committee or the Plan Administrator with regard to the Common Stock Plan. Such terms and consent shall also apply to, and be binding upon, the Beneficiaries, distributees and personal representatives and other successors in interest of each Participant.

B. Notice. Any election made, or notice given by a Participant pursuant to the Common Stock Plan shall be in writing to the Committee, or to such representative as may be designated by the Committee for such purpose. Notice shall be deemed to have been made or given on the date received by the Committee or its designated representative.

C. Competency. If the Committee determines that any person to whom a payment is due hereunder is a minor, or is adjudicated incompetent by reason of physical or mental disability, the Committee shall have the power to cause the payments becoming due to such person to be made to the legal guardian for the benefit of the minor or incompetent, without responsibility of the Corporation or the Committee

10

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to see to the application of such payment, unless prior to such payment claim is made therefore by a duly appointed legal representative. Payments made pursuant to such power shall operate as a complete discharge of the Corporation, the Board of Directors and the Committee.

D. Nonalienation of Benefits. Neither the Participant nor any Beneficiary designated by him or her shall have any right to alienate, assign, or encumber any benefits that are or may be distributed hereunder, nor may any such amounts be subject to attachment, garnishment, levy, execution or other legal or equitable process for the debts, contracts, liabilities, engagements or acts of any Participant or Beneficiary.

E. Administration of Common Stock Plan. Full power and authority to construe, interpret, and administer the Common Stock Plan shall be vested in the Committee. To the extent permitted by law, the Committee may delegate any authority it possesses to the Plan Administrator. To the extent the Committee has delegated authority concerning a matter to the Plan Administrator, any reference in the Common Stock Plan to the "Committee" insofar as it pertains to such matter, shall refer likewise to the Plan Administrator. Decisions of the Committee shall be final, conclusive, and binding upon all parties.

F. Fees and Expenses of Administration. If the Committee so determines, reasonable trustee's fees (if applicable) and reasonable out-of-pocket expenses of administering the Common Stock Plan may be ratably deducted (using average balances) on an annual basis from Corporation Stock Unit Accounts.

G. Effective Date. The terms of this Common Stock Plan, as amended and restated, shall apply to all Director Fees deferred under this Common Stock Plan or one of its predecessors on and after July 1, 2020, except to the extent that retroactive application would adversely affect the rights of a Participant or Beneficiary to the amounts in the applicable Corporation Stock Unit Account at the time of the adoption of this amendment and restatement of the Common Stock Plan.

H. Statements to Participants. Statements will be provided to Participants under the Common Stock Plan on at least an annual basis.

I. Nonforfeitability of Participant Accounts. Each Participant shall be fully vested in his or her Corporation Stock Unit Account, and the right to receive the amounts in the Corporation Stock Unit Account shall be nonforfeitable.

J. Successors Bound. The contractual agreement between the Corporation and each Participant resulting from the execution of a Deferral Election Form shall be binding upon and inure to the benefit of the Corporation, its successors and assigns, and to the Participant and to the Participant's beneficiaries, heirs, executors, administrators and other legal representatives.

11

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K. Governing Laws and Rules of Construction. This Common Stock Plan shall be governed in all respects, whether as to construction, validity or otherwise, by the laws of the State of Delaware unless preempted by Federal law.

L. Compliance & Severability. It is the Corporation's intent to comply with all applicable tax and other laws, including Code Section 409A and the Regulations promulgated thereunder, so that all rights under the Plan will be limited as necessary in the judgment of the Committee to conform therewith. Therefore, consistent with the effectuation of the purposes hereof, each provision of this Common Stock Plan shall be treated as severable, to the end that, if any one or more provisions shall be adjudged or declared illegal, invalid or unenforceable, this Common Stock Plan shall be interpreted, and shall remain in full force and effect, as though such provision or provisions had never been contained herein. It is the intention of the Corporation that the Common Stock Plan established hereunder be "unfunded" for income tax purposes, whether or not the Corporation establishes a rabbi trust, and the provisions hereof shall be construed in a manner to carry out that intention.

M. Ownership of Deferred Director Fees and Continued Director Status. Title to and beneficial ownership of any assets, of whatever nature, which may be allocated by the Corporation to any Corporation Stock Unit Account in the name of any Participant, shall at all times remain with the Corporation and its Subsidiaries, and no Participant or Beneficiary shall have any property interest whatsoever in any specific assets of the Corporation or its Subsidiaries by reason of the establishment of the Common Stock Plan. The rights of each Participant and Beneficiary hereunder shall be limited to enforcing the unfunded, unsecured promise of the Corporation and its Subsidiaries to pay benefits under the Common Stock Plan, and the status of any Participant or Beneficiary shall be that of an unsecured general creditor of the Corporation and its Subsidiaries. Neither the establishment of the Common Stock Plan nor the distribution of any benefits hereunder or any action of the Corporation, its Board of Directors, or any committee thereto, shall be held or construed to confer upon any person the legal right to remain a director of the Corporation or any Subsidiary or any Advisory Board beyond the term for which he or she was elected or appointed to the board(s) on which he or she serves.

12

Exhibit 31.1

Chairman, President and CEO Rule 13a-14(a)/15d-14(a) Certification of Periodic Report (pursuant to Section 302 of the Sarbanes-Oxley Act of 2002)

CERTIFICATION OF PERIODIC REPORT

PURSUANT TO SECTION 302 OF THE SARBANES-OXLEY ACT OF 2002

I, Curtis C. Farmer, certify that:

1.I have reviewed this report on Form 10-Q for the quarterly period ended June 30, 2020 of Comerica Incorporated (the “Registrant”);

2.Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report;

3.Based on my knowledge, the financial statements, and other financial information included in this report, fairly present in all material respects the financial condition, results of operations and cash flows of the Registrant as of, and for, the periods presented in this report;

4.The Registrant's other certifying officer and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal control over financial reporting (as defined in Exchange Act Rules 13a-15(f) and 15(d)-15(f)) for the Registrant and have:

(a)Designed such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under our supervision, to ensure that material information relating to the Registrant, including its consolidated subsidiaries, is made known to us by others within those entities, particularly during the period in which this report is being prepared;

(b)Designed such internal control over financial reporting, or caused such internal control over financial reporting to be designed under our supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles;

(c)Evaluated the effectiveness of the Registrant's disclosure controls and procedures and presented in this report our conclusions about the effectiveness of the disclosure controls and procedures, as of the end of the period covered by this report based on such evaluation; and

(d)Disclosed in this report any change in the Registrant's internal control over financial reporting that occurred during the Registrant's most recent fiscal quarter (the Registrant's fourth fiscal quarter in the case of an annual report) that has materially affected, or is reasonably likely to materially affect, the Registrant's internal control over financial reporting; and

5.The Registrant's other certifying officer and I have disclosed, based on our most recent evaluation of internal control over financial reporting, to the Registrant's auditors and the audit committee of the Registrant's board of directors (or persons performing the equivalent functions):

(a)All significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which are reasonably likely to adversely affect the Registrant's ability to record, process, summarize and report financial information; and

(b)Any fraud, whether or not material, that involves management or other employees who have a significant role in the Registrant's internal control over financial reporting.

Date:			July 30, 2020			/s/ Curtis C. Farmer
						Curtis C. Farmer
						Chairman, President and Chief Executive Officer

Exhibit 31.2

Executive Vice President and CFO Rule 13a-14(a)/15d-14(a) Certification of Periodic Report (pursuant to Section 302 of the Sarbanes-Oxley Act of 2002)

CERTIFICATION OF PERIODIC REPORT

PURSUANT TO SECTION 302 OF THE SARBANES-OXLEY ACT OF 2002

I, James J. Herzog, certify that:

1.I have reviewed this report on Form 10-Q for the quarterly period ended June 30, 2020 of Comerica Incorporated (the “Registrant”);

2.Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report;

3.Based on my knowledge, the financial statements, and other financial information included in this report, fairly present in all material respects the financial condition, results of operations and cash flows of the Registrant as of, and for, the periods presented in this report;

4.The Registrant's other certifying officer and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal control over financial reporting (as defined in Exchange Act Rules 13a-15(f) and 15(d)-15(f)) for the Registrant and have:

(a)Designed such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under our supervision, to ensure that material information relating to the Registrant, including its consolidated subsidiaries, is made known to us by others within those entities, particularly during the period in which this report is being prepared;

(b)Designed such internal control over financial reporting, or caused such internal control over financial reporting to be designed under our supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles;

(c)Evaluated the effectiveness of the Registrant's disclosure controls and procedures and presented in this report our conclusions about the effectiveness of the disclosure controls and procedures, as of the end of the period covered by this report based on such evaluation; and

(d)Disclosed in this report any change in the Registrant's internal control over financial reporting that occurred during the Registrant's most recent fiscal quarter (the Registrant's fourth fiscal quarter in the case of an annual report) that has materially affected, or is reasonably likely to materially affect, the Registrant's internal control over financial reporting; and

5.The Registrant's other certifying officer and I have disclosed, based on our most recent evaluation of internal control over financial reporting, to the Registrant's auditors and the audit committee of the Registrant's board of directors (or persons performing the equivalent functions):

(a)All significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which are reasonably likely to adversely affect the Registrant's ability to record, process, summarize and report financial information; and

(b)Any fraud, whether or not material, that involves management or other employees who have a significant role in the Registrant's internal control over financial reporting.

Date:			July 30, 2020			/s/ James J. Herzog
						James J. Herzog
						Executive Vice President and Chief Financial Officer

Exhibit 32

Section 1350 Certification of Periodic Report (pursuant to Section 906 of the Sarbanes-Oxley Act of 2002)

CERTIFICATION OF PERIODIC REPORT

PURSUANT TO SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

The undersigned, Curtis C. Farmer, Chairman, President and Chief Executive Officer, and James J. Herzog, Executive Vice President and Chief Financial Officer, of Comerica Incorporated (the “Company”), certify, pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, 18 U.S.C. Section 1350, that:

(1)the Quarterly Report on Form 10-Q of the Company for the quarterly period ended June 30, 2020 (the “Report”) fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934 (15 U.S.C. 78m or 78o(d)); and

(2)the information contained in the Report fairly presents, in all material respects, the financial condition and results of operations of the Company.

Dated:			July 30, 2020			/s/ Curtis C. Farmer
						Curtis C. Farmer
						Chairman, President and Chief Executive Officer
						/s/ James J. Herzog
						James J. Herzog
						Executive Vice President and Chief Financial Officer

v3.20.2

Document And Entity Information - shares	6 Months Ended
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Entity Central Index Key	0000028412
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q2
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Entity Address, Address Line One	1717 Main Street, MC 6404
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City Area Code	(214)
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Security Exchange Name	NYSE

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v3.20.2

Consolidated Balance Sheets - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
ASSETS
Cash and due from banks	$ 1,048	$ 973
Interest-bearing deposits with banks	12,263	4,845
Other short-term investments	153	155
Investment securities available-for-sale	12,759	12,398
Commercial loans	33,826	31,473
Real estate construction loans	3,952	3,455
Commercial mortgage loans	9,925	9,559
Lease financing	589	588
International loans	1,104	1,009
Residential mortgage loans	1,886	1,845
Consumer loans	2,164	2,440
Total loans	53,446	50,369
Less allowance for loan losses	(1,007)	(637)
Net loans	52,439	49,732
Premises and equipment	450	457
Accrued income and other assets	5,285	4,842
Total assets	84,397	73,402
LIABILITIES AND SHAREHOLDERS' EQUITY
Noninterest-bearing deposits	35,582	27,382
Money market and interest-bearing checking deposits	26,895	24,527
Savings deposits	2,500	2,184
Customer certificates of deposit	2,656	2,978
Other time deposits	0	133
Foreign office time deposits	87	91
Total interest-bearing deposits	32,138	29,913
Total deposits	67,720	57,295
Short-term borrowings	752	71
Accrued expenses and other liabilities	1,602	1,440
Medium- and long-term debt	6,521	7,269
Total liabilities	76,595	66,075
Fixed rate reset non-cumulative perpetual preferred stock, series A, no par value, $100,000 liquidation preference per share: Authorized - 4,000 shares, Issued - 4,000 shares at 6/30/2020	395	0
Common stock - $5 par value: Authorized - 325,000,000 shares; Issued - 228,164,824 shares	1,141	1,141
Capital surplus	2,173	2,174
Accumulated other comprehensive income (loss)	158	(235)
Retained earnings	9,404	9,538
Less cost of common stock in treasury - 89,124,560 shares at 6/30/20 and 86,069,234 shares at 12/31/19	(5,469)	(5,291)
Total shareholders' equity	7,802	7,327
Total liabilities and shareholders' equity	$ 84,397	$ 73,402

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v3.20.2

Consolidated Balance Sheets (Parenthetical) - $ / shares	Jun. 30, 2020	Dec. 31, 2019
Statement of Financial Position [Abstract]
Preferred Stock, No Par Value	$ 0
Preferred Stock, Shares Authorized	4,000
Preferred Stock, Shares Issued	4,000
Common stock, par value	$ 5	$ 5
Common stock, authorized shares	325,000,000	325,000,000
Common stock, issued shares	228,164,824	228,164,824
Shares in treasury	89,124,560	86,069,234

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- Definition Number of common and preferred shares that were previously issued and that were repurchased by the issuing entity and held in treasury on the financial statement date. This stock has no voting rights and receives no dividends. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.29,30) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 30 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6405813&loc=d3e23239-112655 + Details Name: us-gaap_TreasuryStockShares Namespace Prefix: us-gaap_ Data Type: xbrli:sharesItemType Balance Type: na Period Type: instant

v3.20.2

Consolidated Statements Of Comprehensive Income - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
INTEREST INCOME
Interest and fees on loans		$ 434	$ 635	$ 951	$ 1,256
Interest on investment securities		74	75	148	147
Interest on short-term investments		3	17	21	34
Total interest income		511	727	1,120	1,437
INTEREST EXPENSE
Interest on deposits		20	67	76	119
Interest on short-term borrowings		1	6	1	7
Interest on medium- and long-term debt	[1]	19	51	59	102
Total interest expense		40	124	136	228
Net interest income		471	603	984	1,209
Provision for credit losses		138	44	549	31
Net interest income after provision for credit losses		333	559	435	1,178
NONINTEREST INCOME
Card Fees		68	65	127	128
Fiduciary income		52	52	106	101
Service charges on deposit accounts		42	51	91	102
Commercial lending fees		17	21	34	43
Foreign exchange income		9	11	20	22
Bank-owned life insurance		9	11	21	20
Letter of credit fees		9	10	18	19
Brokerage fees		5	7	12	14
Net securities losses		1	0	0	(8)
Other noninterest income		35	22	55	47
Total noninterest income		247	250	484	488
NONINTEREST EXPENSES
Salaries and benefits expense		249	245	491	510
Outside processing fee expense		62	65	119	128
Occupancy expense		37	37	74	74
Software expense		39	28	76	57
Equipment expense		12	12	24	24
Advertising expense		8	9	15	14
FDIC insurance expense		8	6	16	11
Other noninterest expenses		25	22	50	39
Total noninterest expenses		440	424	865	857
Income before income taxes		140	385	54	809
Provision for income taxes		27	87	6	172
Net income		113	298	48	637
Less income allocated to participating securities		1	1	1	3
Net income attributable to common shares		$ 112	$ 297	$ 47	$ 634
Basic earnings per common share		$ 0.81	$ 1.95	$ 0.34	$ 4.10
Diluted earnings per common share		$ 0.80	$ 1.94	$ 0.34	$ 4.06
Comprehensive income		$ 97	$ 429	$ 441	$ 864
Cash dividends declared on common stock		$ 98	$ 100	$ 192	$ 205
Cash dividends declared per common share		$ 0.68	$ 0.67	$ 1.36	$ 1.34
[1] Includes the effects of hedging.

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- Definition The amount of expense incurred during the period from fees for services performed by outside vendors. + References No definition available. + Details Name: cma_OutsideProcessingFeeExpense Namespace Prefix: cma_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: duration

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- Definition The amount of expense incurred during the period from amortization of computer software and fees for software maintenance and rental. + References No definition available. + Details Name: cma_SoftwareExpenses Namespace Prefix: cma_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: duration

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- Definition Amount charged to advertising expense for the period, which are expenses incurred with the objective of increasing revenue for a specified brand, product or product line. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 720 -SubTopic 35 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6420018&loc=d3e36677-107848 + Details Name: us-gaap_AdvertisingExpense Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: duration

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- Definition Earnings on or other increases in the value of the cash surrender value of bank owned life insurance policies. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 220 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-04.13) -URI http://asc.fasb.org/extlink&oid=120399700&loc=SL114874048-224260 + Details Name: us-gaap_BankOwnedLifeInsuranceIncome Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: credit Period Type: duration

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- Definition Aggregate dividends declared during the period for each share of common stock outstanding. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.3-04) -URI http://asc.fasb.org/extlink&oid=120397183&loc=d3e187085-122770 + Details Name: us-gaap_CommonStockDividendsPerShareDeclared Namespace Prefix: us-gaap_ Data Type: num:perShareItemType Balance Type: na Period Type: duration

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- Definition Amount after tax of increase (decrease) in equity from transactions and other events and circumstances from net income and other comprehensive income. Excludes changes in equity resulting from investments by owners and distributions to owners. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 810 -SubTopic 10 -Section 55 -Paragraph 4K -URI http://asc.fasb.org/extlink&oid=120409616&loc=SL4591552-111686 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 1A -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=121641772&loc=SL7669619-108580 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 220 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-04(20)) -URI http://asc.fasb.org/extlink&oid=120400993&loc=SL114874131-224263 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 810 -SubTopic 10 -Section 45 -Paragraph 19 -URI http://asc.fasb.org/extlink&oid=108774443&loc=SL4569616-111683 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 1B -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=121641772&loc=SL7669625-108580 Reference 6: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03(22)) -URI http://asc.fasb.org/extlink&oid=120395209&loc=SL114868664-224227 Reference 7: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 220 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-04(24)) -URI http://asc.fasb.org/extlink&oid=120399700&loc=SL114874048-224260 + Details Name: us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: credit Period Type: duration

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v3.20.2

Consolidated Statements Of Changes In Shareholders' Equity - USD ($) shares in Millions, $ in Millions	Total	Preferred Stock	Common Stock	Capital Surplus	Accumulated Other Comprehensive Loss	Retained Earnings	Treasury Stock
BALANCE (in shares) at Dec. 31, 2018			160.1
BALANCE at Dec. 31, 2018	$ 7,507		$ 1,141	$ 2,148	$ (609)	$ 8,781	$ (3,954)
Net income	637					637
Other comprehensive income (loss), net of tax	227				227
Cash dividends declared on common stock	(205)					(205)
Purchase of common stock	859			0			859
Purchase of common stock (in shares)			(10.9)
Issuance of preferred stock	0
Net issuance of common stock under employee stock plans	2			12		23	33
Net issuance of common stock under employee stock plans (in shares)			0.6
Share-based compensation	32			32
BALANCE at Jun. 30, 2019	7,323		$ 1,141	2,168	(382)	9,176	(4,780)
BALANCE (in shares) at Jun. 30, 2019			149.8
BALANCE (in shares) at Mar. 31, 2019			155.4
BALANCE at Mar. 31, 2019	7,409		$ 1,141	2,159	(513)	8,979	(4,357)
Net income	298					298
Other comprehensive income (loss), net of tax	131				131
Cash dividends declared on common stock	(100)					(100)
Purchase of common stock	425						425
Purchase of common stock (in shares)			(5.7)
Net issuance of common stock under employee stock plans	2			1		1	2
Net issuance of common stock under employee stock plans (in shares)			0.1
Share-based compensation	8			8
BALANCE at Jun. 30, 2019	7,323		$ 1,141	2,168	(382)	9,176	(4,780)
BALANCE (in shares) at Jun. 30, 2019			149.8
BALANCE (in shares) at Dec. 31, 2019			142.1
BALANCE at Dec. 31, 2019	7,327		$ 1,141	2,174	(235)	9,538	(5,291)
Net income	48					48
Other comprehensive income (loss), net of tax	393				393
Cash dividends declared on common stock	(192)					(192)
Purchase of common stock	194			0			194
Purchase of common stock (in shares)			(3.4)
Issuance of preferred stock	395	$ 395
Net issuance of common stock under employee stock plans	0			13		3	16
Net issuance of common stock under employee stock plans (in shares)			0.3
Share-based compensation	12			12
BALANCE at Jun. 30, 2020	7,802	395	$ 1,141	2,173	158	9,404	(5,469)
BALANCE (in shares) at Jun. 30, 2020			139.0
BALANCE (in shares) at Mar. 31, 2020			139.0
BALANCE at Mar. 31, 2020	7,402		$ 1,141	2,168	174	9,389	(5,470)
Net income	113					113
Other comprehensive income (loss), net of tax	(16)				(16)
Cash dividends declared on common stock	(98)					(98)
Purchase of common stock	1						1
Issuance of preferred stock	395	395
Net issuance of common stock under employee stock plans	1			1
Share-based compensation	4			4
BALANCE at Jun. 30, 2020	$ 7,802	$ 395	$ 1,141	$ 2,173	$ 158	$ 9,404	$ (5,469)
BALANCE (in shares) at Jun. 30, 2020			139.0

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v3.20.2

Consolidated Statements Of Changes In Shareholders' Equity (Parenthetical) - $ / shares	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Statement of Stockholders' Equity [Abstract]
Cash dividends declared on stock, per common share	$ 0.68	$ 0.67	$ 1.36	$ 1.34

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v3.20.2

Consolidated Statements Of Cash Flows - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
OPERATING ACTIVITIES
Net income	$ 48	$ 637
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for credit losses	549	31
Benefit for deferred income taxes	(95)	(4)
Depreciation and amortization	55	57
Net periodic defined benefit credit	(13)	(14)
Share-based compensation expense	12	32
Net amortization of securities	1	1
Net securities losses	0	8
Net change in accrued income receivable	43	(12)
Net change in accrued expenses payable	(64)	(86)
Other, net	208	(225)
Net cash provided by operating activities	744	425
INVESTING ACTIVITIES
Maturities and redemptions of investment securities available-for-sale	1,311	991
Sales of investment securities available-for-sale	0	987
Purchases of investment securities available-for-sale	(1,387)	(2,043)
Net change in loans	(3,229)	(1,685)
Proceeds from sales of foreclosed property	1	0
Net increase in premises and equipment	(29)	(29)
Purchases of Federal Home Loan Bank stock	(51)	(49)
Redemptions of Federal Home Loan Bank stock	30	0
Proceeds from bank-owned life insurance settlements	10	7
Net cash used in investing activities	(3,344)	(1,821)
FINANCING ACTIVITIES
Net change in deposits	10,327	(209)
Net change in short-term borrowings	681	1,689
Maturities and redemptions of medium- and long-term debt	(925)	(350)
Issuances and advances of medium- and long-term debt	0	350
Issuance of preferred stock	395	0
Repurchases of common stock	(199)	(872)
Cash dividends paid on common stock	(191)	(203)
Issuances of common stock under employee stock plans	5	11
Net cash provided by financing activities	10,093	416
Net increase (decrease) in cash and cash equivalents	7,493	(980)
Cash and cash equivalents at beginning of period	5,818	4,561
Cash and cash equivalents at end of period	13,311	3,581
Interest paid	152	220
Income tax paid	77	161
Noncash investing and financing activities:
Loans transferred to other real estate	$ 1	$ 2

X

- Definition The net cash inflow (outflow) from purchases, sales and disposals of property, plant, and equipment. + References No definition available. + Details Name: cma_NetIncreaseInFixedAssets Namespace Prefix: cma_ Data Type: xbrli:monetaryItemType Balance Type: credit Period Type: duration

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- Definition The sum of the periodic adjustments of the differences between securities' face values and purchase prices that are charged against earnings. This is called accretion if the security was purchased at a discount and amortization if it was purchased at premium. As a noncash item, this element is an adjustment to net income when calculating cash provided by or used in operations using the indirect method. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3602-108585 + Details Name: us-gaap_AccretionAmortizationOfDiscountsAndPremiumsInvestments Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: credit Period Type: duration

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- Definition Amount of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Excludes cash and cash equivalents within disposal group and discontinued operation. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3044-108585 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section 45 -Paragraph 1 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=121566466&loc=d3e6676-107765 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.1) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 + Details Name: us-gaap_CashAndCashEquivalentsAtCarryingValue Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: instant

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- Definition Amount of increase (decrease) in cash, cash equivalents, and cash and cash equivalents restricted to withdrawal or usage; including effect from exchange rate change. Cash includes, but is not limited to, currency on hand, demand deposits with banks or financial institutions, and other accounts with general characteristics of demand deposits. Cash equivalents include, but are not limited to, short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 830 -SubTopic 230 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=98513438&loc=d3e33268-110906 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 24 -URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3521-108585 + Details Name: us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: duration

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- References No definition available. + Details Name: us-gaap_CashFlowNoncashInvestingAndFinancingActivitiesDisclosureAbstract Namespace Prefix: us-gaap_ Data Type: xbrli:stringItemType Balance Type: na Period Type: duration

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- Definition Amount of unrealized and realized gain (loss) on investment in debt and equity securities. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03(9)(a)) -URI http://asc.fasb.org/extlink&oid=120395209&loc=SL114868664-224227 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03(7)(c)) -URI http://asc.fasb.org/extlink&oid=120395209&loc=SL114868664-224227 + Details Name: us-gaap_DebtAndEquitySecuritiesGainLoss Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: credit Period Type: duration

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- Definition Amount of deferred income tax expense (benefit) pertaining to income (loss) from continuing operations. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SAB Topic 6.I.7) -URI http://asc.fasb.org/extlink&oid=116825942&loc=d3e330036-122817 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SAB Topic 6.I.Fact.1) -URI http://asc.fasb.org/extlink&oid=116825942&loc=d3e330036-122817 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.4-08(h)) -URI http://asc.fasb.org/extlink&oid=120395691&loc=d3e23780-122690 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SAB Topic 6.I.Fact.2) -URI http://asc.fasb.org/extlink&oid=116825942&loc=d3e330036-122817 Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3602-108585 Reference 6: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 9 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32639-109319 + Details Name: us-gaap_DeferredIncomeTaxExpenseBenefit Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: duration

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- Definition Amount of net periodic benefit cost (credit) for defined benefit plan. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 6 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e2709-114920 Reference 2: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 55 -Paragraph 17 -URI http://asc.fasb.org/extlink&oid=118257860&loc=d3e4179-114921 Reference 3: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 55 -Paragraph 18 -URI http://asc.fasb.org/extlink&oid=118257860&loc=d3e4587-114921 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (h) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 + Details Name: us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: duration

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- Definition The current period expense charged against earnings on long-lived, physical assets not used in production, and which are not intended for resale, to allocate or recognize the cost of such assets over their useful lives; or to record the reduction in book value of an intangible asset over the benefit period of such asset; or to reflect consumption during the period of an asset that is not used in production. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 360 -SubTopic 10 -Section 50 -Paragraph 1 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=6391035&loc=d3e2868-110229 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3602-108585 + Details Name: us-gaap_DepreciationAndAmortization Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: duration

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- Definition The amount of cash paid during the current period to foreign, federal, state, and local authorities as taxes on income, net of any cash received during the current period as refunds for the overpayment of taxes. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=121583591&loc=d3e4297-108586 + Details Name: us-gaap_IncomeTaxesPaidNet Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: credit Period Type: duration

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- Definition The increase (decrease) during the reporting period in the aggregate amount of expenses incurred but not yet paid. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3602-108585 + Details Name: us-gaap_IncreaseDecreaseInAccruedLiabilities Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: duration

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- Definition The net cash inflow or outflow for the increase (decrease) in the beginning and end of period deposits balances. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3095-108585 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 230 -Section 45 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=121551529&loc=d3e60009-112784 + Details Name: us-gaap_IncreaseDecreaseInDeposits Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: duration

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- Definition The increase (decrease) during the reporting period in the aggregate amount due to the entity in the form of unpaid interest and dividends. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3602-108585 + Details Name: us-gaap_IncreaseDecreaseInInterestAndDividendsReceivable Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: credit Period Type: duration

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- Definition Amount of increase (decrease) in operating assets after deduction of operating liabilities classified as other. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3602-108585 + Details Name: us-gaap_IncreaseDecreaseInOtherOperatingCapitalNet Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: credit Period Type: duration

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- Definition Amount of cash paid for interest, including, but not limited to, capitalized interest and payment to settle zero-coupon bond attributable to accreted interest of debt discount and debt instrument with insignificant coupon interest rate in relation to effective interest rate of borrowing attributable to accreted interest of debt discount; classified as operating and investing activities. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=121583591&loc=d3e4297-108586 + Details Name: us-gaap_InterestPaid Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: credit Period Type: duration

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- Definition Amount of cash inflow (outflow) from financing activities, including discontinued operations. Financing activity cash flows include obtaining resources from owners and providing them with a return on, and a return of, their investment; borrowing money and repaying amounts borrowed, or settling the obligation; and obtaining and paying for other resources obtained from creditors on long-term credit. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 24 -URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3521-108585 + Details Name: us-gaap_NetCashProvidedByUsedInFinancingActivities Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: duration

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- References No definition available. + Details Name: us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract Namespace Prefix: us-gaap_ Data Type: xbrli:stringItemType Balance Type: na Period Type: duration

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- Definition Amount of cash inflow (outflow) from investing activities, including discontinued operations. Investing activity cash flows include making and collecting loans and acquiring and disposing of debt or equity instruments and property, plant, and equipment and other productive assets. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 24 -URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3521-108585 + Details Name: us-gaap_NetCashProvidedByUsedInInvestingActivities Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: duration

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- References No definition available. + Details Name: us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract Namespace Prefix: us-gaap_ Data Type: xbrli:stringItemType Balance Type: na Period Type: duration

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- Definition Amount of cash inflow (outflow) from operating activities, including discontinued operations. Operating activity cash flows include transactions, adjustments, and changes in value not defined as investing or financing activities. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 25 -URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3536-108585 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 24 -URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3521-108585 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3602-108585 + Details Name: us-gaap_NetCashProvidedByUsedInOperatingActivities Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: na Period Type: duration

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- References No definition available. + Details Name: us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract Namespace Prefix: us-gaap_ Data Type: xbrli:stringItemType Balance Type: na Period Type: duration

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- Definition The net cash outflow or inflow for the increase (decrease) in the beginning and end of period of loan and lease balances which are not originated or purchased specifically for resale. Includes cash payments and proceeds associated with (a) loans held-for-investment, (b) leases held-for-investment, and (c) both. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 3 -Subparagraph (SX 210.12-04(a)) -URI http://asc.fasb.org/extlink&oid=120395691&loc=d3e24072-122690 + Details Name: us-gaap_PaymentsForProceedsFromLoansAndLeases Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: credit Period Type: duration

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- Definition The cash outflow to reacquire common stock during the period. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 15 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3291-108585 + Details Name: us-gaap_PaymentsForRepurchaseOfCommonStock Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: credit Period Type: duration

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- Definition Amount of cash outflow in the form of ordinary dividends to common shareholders of the parent entity. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 15 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3291-108585 + Details Name: us-gaap_PaymentsOfDividendsCommonStock Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: credit Period Type: duration

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- Definition The cash outflow to acquire debt and equity securities not classified as either held-to-maturity securities or trading securities which would be classified as available-for-sale securities and reported at fair value, with unrealized gains and losses excluded from earnings and reported in a separate component of shareholders' equity. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 45 -Paragraph 11 -URI http://asc.fasb.org/extlink&oid=121553693&loc=d3e26853-111562 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 13 -Subparagraph (a),(b) -URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3213-108585 + Details Name: us-gaap_PaymentsToAcquireAvailableForSaleSecurities Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: credit Period Type: duration

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- Definition Amount of cash outflow to acquire Federal Home Loan Bank (FHLB) stock. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 13 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3213-108585 + Details Name: us-gaap_PaymentsToAcquireFederalHomeLoanBankStock Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: credit Period Type: duration

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- Definition The cash inflow from the additional capital contribution to the entity. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 14 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3255-108585 + Details Name: us-gaap_ProceedsFromIssuanceOfCommonStock Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: duration

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- Definition The cash inflow from a debt initially having maturity due after one year or beyond the operating cycle, if longer. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 14 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3255-108585 + Details Name: us-gaap_ProceedsFromIssuanceOfLongTermDebt Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: duration

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- Definition Amount of cash inflow for proceeds from settlement of corporate-owned life insurance policy, classified as investing activities. Includes, but is not limited to, bank-owned life insurance policy. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 21C -URI http://asc.fasb.org/extlink&oid=121586364&loc=SL94080552-108585 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 12 -URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3179-108585 + Details Name: us-gaap_ProceedsFromLifeInsurancePolicies Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: duration

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- Definition Amount of cash inflow from maturity, prepayment and call of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 45 -Paragraph 11 -URI http://asc.fasb.org/extlink&oid=121553693&loc=d3e26853-111562 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 11 -URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3151-108585 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 12 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3179-108585 + Details Name: us-gaap_ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: duration

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- Definition The net cash inflow or outflow for borrowing having initial term of repayment within one year or the normal operating cycle, if longer. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 3 -Subparagraph (SX 210.12-04(a)) -URI http://asc.fasb.org/extlink&oid=120395691&loc=d3e24072-122690 + Details Name: us-gaap_ProceedsFromRepaymentsOfShortTermDebt Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: duration

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- Definition The cash inflow associated with the sale of debt and equity securities classified as available-for-sale securities. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 45 -Paragraph 11 -URI http://asc.fasb.org/extlink&oid=121553693&loc=d3e26853-111562 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 12 -Subparagraph (a),(b) -URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3179-108585 + Details Name: us-gaap_ProceedsFromSaleOfAvailableForSaleSecurities Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: duration

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- Definition The cash inflow from the sale assets received in full or partial satisfaction of a receivable including real and personal property; equity interests in corporations, partnerships, and joint ventures; and beneficial interests in trusts. Foreclosed assets also include loans that are treated as if the underlying collateral had been foreclosed because the institution has taken possession of the collateral, even though legal foreclosure or repossession proceedings have not taken place. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 12 -URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3179-108585 + Details Name: us-gaap_ProceedsFromSaleOfForeclosedAssets Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: duration

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- Definition The consolidated profit or loss for the period, net of income taxes, including the portion attributable to the noncontrolling interest. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.4-08(g)(1)(ii)) -URI http://asc.fasb.org/extlink&oid=120395691&loc=d3e23780-122690 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 1A -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=121641772&loc=SL7669619-108580 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 205 -SubTopic 20 -Section 50 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=109222650&loc=SL51721683-107760 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting 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- Definition Amount of expense related loan transactions, lease transactions, credit loss from transactions other than loan and lease transactions, and other loss based on assessment of uncollectability from the counterparty to reduce the account to their net realizable value. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 11B -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=121611835&loc=SL6953423-111524 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 220 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-04.11) -URI http://asc.fasb.org/extlink&oid=120399700&loc=SL114874048-224260 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3602-108585 + Details Name: us-gaap_ProvisionForLoanLeaseAndOtherLosses Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: duration

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- Definition The cash outflow during the period from the repayment of aggregate short-term and long-term debt. Excludes payment of capital lease obligations. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 15 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3291-108585 + Details Name: us-gaap_RepaymentsOfDebt Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: credit Period Type: duration

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- Definition Amount of cash outflow for repayment of Federal Home Loan Bank (FHLBank) borrowing, classified as financing activity. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 15 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3291-108585 + Details Name: us-gaap_RepaymentsOfFederalHomeLoanBankBorrowings Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: credit Period Type: duration

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v3.20.2

Basis of Presentation and Accounting Policies	6 Months Ended
	Jun. 30, 2020
Accounting Policies [Abstract]
Basis of Presentation and Accounting Policies	BASIS OF PRESENTATION AND ACCOUNTING POLICIES Organization The accompanying unaudited consolidated financial statements were prepared in accordance with United States (U.S.) generally accepted accounting principles (GAAP) for interim financial information and with the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, the statements do not include all of the information and footnotes required by GAAP for complete financial statements. In the opinion of management, all adjustments (consisting of normal recurring accruals) considered necessary for a fair presentation were included. The results of operations for the six months ended June 30, 2020 are not necessarily indicative of the results that may be expected for the year ending December 31, 2020. Certain items in prior periods were reclassified to conform to the current presentation. For further information, refer to the consolidated financial statements and footnotes thereto included in the Annual Report of Comerica Incorporated and Subsidiaries (the Corporation) on Form 10-K for the year ended December 31, 2019. Allowance for Credit Losses         The allowance for credit losses includes both the allowance for loan losses and the allowance for credit losses on lending-related commitments.         The Corporation disaggregates the loan portfolio into segments for purposes of determining the allowance for credit losses. These segments are based on the level at which the Corporation develops, documents and applies a systematic methodology to determine the allowance for credit losses. The Corporation's portfolio segments are business loans and retail loans. Business loans include the commercial, real estate construction, commercial mortgage, lease financing and international loan portfolios. Retail loans consist of residential mortgage and consumer loans, including home equity loans.         Effective January 1, 2020, the Corporation adopted the provisions of Accounting Standards Update (ASU) No. 2016-13, "Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments," commonly referred to as the current expected credit loss (CECL) model, for all financial assets, except those accounted for at fair value through net income, using the modified retrospective approach.         Under Topic 326, current expected credit losses are estimated over the contractual life of the loan portfolio, considering all available relevant information, including historical and current conditions as well as reasonable and supportable forecasts of future events. The previous accounting principle estimated probable, estimable losses inherent in the portfolio.         At adoption, the Corporation’s estimate of current expected credit losses in accordance with Topic 326 resulted in a $17 million day-one decrease in the overall allowance for credit losses, from $668 million at December 31, 2019 under the incurred loss model. The Corporation recognized a corresponding $13 million increase to retained earnings and a $4 million reduction to deferred tax assets. A similar adjustment at December 31, 2019 would have caused a 2-basis-point increase in the Common Equity Tier 1 (CET1) capital ratio. Business loans, comprising approximately 91 percent of the Corporation’s total loan portfolio at transition, consist of loans and lending arrangements with generally short contractual maturities. As a result, the allowance for credit losses for business loans decreased $42 million. The allowance for credit losses increased $25 million for retail loans, given their longer contractual maturities.         Topic 326 also requires expected credit losses on available-for-sale (AFS) debt securities to be recorded as an allowance for credit losses. For certain types of debt securities, such as U.S. Treasuries and other securities with government guarantees, entities may expect zero credit losses. The zero-loss expectation applies to all the Corporation’s securities and no allowance for credit losses was recorded on its AFS securities portfolio at transition. Allowance for Loan Losses         The allowance for loan losses is estimated on a quarterly basis and represents management’s estimates of current expected credit losses in the Corporation’s loan portfolio. Pools of loans with similar risk characteristics are collectively evaluated while loans that no longer share risk characteristics with loan pools are evaluated individually.         Collective loss estimates are determined by applying reserve factors, designed to estimate current expected credit losses, to amortized cost balances over the remaining contractual life of the collectively evaluated portfolio. Loans with similar risk characteristics are aggregated into homogeneous pools. Business loans are assigned to pools based primarily on business line and the Corporation’s internal risk rating system. For retail loans, pools are based on loan type, past due status and credit scores. Reserve factors are based on estimated probability of default for each pool, set to a default horizon based on contractual life, and loss given default. Historical estimates are calibrated to economic forecasts over the reasonable and supportable forecast period based on the projected performance of specific economic variables that statistically correlate with each of the probability of default and loss given default pools.         The calculation of current expected credit losses is inherently subjective, as it requires management to exercise judgment in determining appropriate factors used to determine the allowance. Some of the most significant factors in the quantitative allowance estimate are assigning internal risk ratings to loans, selecting the economic forecasts used to calibrate the reserve factors and determining the reasonable and supportable forecast period. •Internal Risk Ratings: Loss factors are dependent on loan risk ratings for business loans. Risk ratings are assigned at origination, based on inherent credit risk, and may be updated based on new information that becomes available, periodic reviews of credit quality, a change in borrower performance or modifications to lending agreements. •Economic Forecasts: Management selects economic variables it believes to be most relevant based on the composition of the loan portfolio and customer base, including forecasted levels of employment, gross domestic product, corporate bond and treasury spreads, industrial production levels, consumer and commercial real estate price indices as well as housing statistics. Different economic forecast scenarios ranging from more benign to more severe are evaluated each reporting period to forecast losses over the contractual life of the loan portfolio. •Forecast Period: Economic forecasts are applied over the period management believes it can estimate reasonable and supportable forecasts. Forecast periods may be adjusted in response to changes in the economic environment. To estimate losses for contractual periods that extend beyond the forecast horizon, the Corporation reverts to an average historical loss experience. The Corporation typically forecasts economic variables over a two-year horizon, followed by an immediate reversion to an average historical loss experience that generally incorporates a full economic cycle. Management reviews this methodology on at least an annual basis.         The allowance for loan losses also includes qualitative adjustments to bring the allowance to the level management believes is appropriate based on factors that have not otherwise been fully accounted for, including adjustments for foresight risk, input imprecision and model imprecision. Foresight risk reflects the inherent imprecision in forecasting economic variables, including determining the depth and duration of economic cycles and their impact to relevant economic variables. The Corporation may make qualitative adjustments based on its evaluation of different forecast scenarios and known recent events impacting relevant economic variables. Input imprecision factors address the risk that certain model inputs may not reflect all available information including (i) risk factors that have not been fully addressed in internal risk ratings, (ii) changes in lending policies and procedures, (iii) changes in the level and quality of experience held by lending management, (iv) imprecision in the risk rating system and (v) limitations in data available for certain loan portfolios. Model imprecision considers known model limitations and model updates not yet fully reflected in the quantitative estimate.          The determination of the appropriate qualitative adjustment is based on management's analysis of current and expected economic conditions and their impact to the portfolio, as well as internal credit risk movements and a qualitative assessment of the lending environment, including underwriting standards. Management recognizes the sensitivity of various assumptions made in the quantitative modeling of expected losses and may adjust reserves depending upon the level of uncertainty that currently exists in one or more assumptions.         Credit losses for loans that no longer share risk characteristics with the loan pools are estimated on an individual basis. Individual credit loss estimates are typically performed for nonaccrual loans and modified loans classified as troubled debt restructurings (TDRs) and are based on one of several methods, including the estimated fair value of the underlying collateral, observable market value of similar debt or the present value of expected cash flows. The Corporation considers certain loans to be collateral-dependent if the borrower is experiencing financial difficulty and management expects repayment for the loan to be substantially through the operation or sale of the collateral. For collateral-dependent loans, loss estimates are based on the fair value of collateral, less estimated cost to sell (if applicable). Collateral values supporting individually evaluated loans are assessed quarterly and appraisals are typically obtained at least annually.         The total allowance for loan losses is sufficient to absorb expected credit losses over the contractual life of the portfolio. Unanticipated events impacting the economy, including political instability or global events affecting the U.S. economy, could cause changes to expectations for current conditions and economic forecasts that result in an unanticipated increase in the allowance. Significant increases in current portfolio exposures or changes in credit characteristics could also increase the amount of the allowance. Such events, or others of similar nature, may result in the need for additional provision for credit losses in order to maintain an allowance that complies with credit risk and accounting policies.         Loans deemed uncollectible are charged off and deducted from the allowance. Recoveries on loans previously charged off are added to the allowance.         Credit losses are not estimated for accrued interest receivable as interest that is deemed uncollectible is written off through interest income. Allowance for Credit Losses on Lending-Related Commitments The allowance for credit losses on lending-related commitments estimates current expected credit losses on collective pools of letters of credit and unused commitments to extend credit based on reserve factors, determined in a manner similar to business loans, multiplied by a probability of draw estimate, based on historical experience and credit risk, applied to commitment amounts. The allowance for credit losses on lending-related commitments is included in accrued expenses and other liabilities on the Consolidated Balance Sheets, with the corresponding charge included in the provision for credit losses on the Consolidated Statements of Comprehensive Income. Goodwill         Effective January 1, 2020, the Corporation prospectively adopted the provisions of ASU No. 2017-04, “Intangibles - Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment,” (ASU 2017-04), eliminating the second step of goodwill impairment testing, under which the implied fair value of goodwill was determined as if the reporting unit were being acquired in a business combination. Under ASU 2017-04, the Corporation will compare the fair value of a reporting unit with its carrying amount and recognize an impairment charge for any amount by which the carrying amount exceeds the reporting unit’s fair value, to the extent that the loss recognized does not exceed the amount of goodwill allocated to that reporting unit. The adoption of ASU 2017-04 did not impact the Corporation’s current financial condition or results of operations.         Goodwill, included in accrued income and other assets on the Consolidated Balance Sheets, is initially recorded as the excess of the purchase price over the fair value of net assets acquired in a business combination and is subsequently evaluated at least annually for impairment. Goodwill impairment testing is performed at the reporting unit level, equivalent to a business segment or one level below. The Corporation has three reporting units: the Commercial Bank, the Retail Bank and Wealth Management.         The Corporation performs its annual evaluation of goodwill impairment in the third quarter of each year and may elect to perform a quantitative impairment analysis or first conduct a qualitative analysis to determine if a quantitative analysis is necessary. Additionally, the Corporation evaluates goodwill impairment on an interim basis if events or changes in circumstances between annual tests indicate additional testing may be warranted to determine if goodwill might be impaired. Factors considered in the assessment of the likelihood of impairment include macroeconomic conditions, industry and market considerations, stock performance of the Corporation and its peers, financial performance of the reporting units, and previous results of goodwill impairment tests, amongst other factors. Based on the results of the qualitative analysis, the Corporation determines whether a quantitative test is deemed necessary. The quantitative test compares the estimated fair value of identified reporting units with their carrying amount, including goodwill. If the estimated fair value of the reporting unit is less than the carrying value, an impairment charge would be recorded for the excess, not to exceed the amount of goodwill allocated to the reporting unit. Software         Effective January 1, 2020, the Corporation adopted the provisions of ASU No. 2018-15, “Intangibles - Goodwill and Other - Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract," using a prospective approach for implementation costs incurred subsequent to the adoption of the standard. Amortization expense from capitalized implementation costs of hosting arrangements that are service contracts and fees associated with the hosting elements of the arrangements, are included in software expense in the Consolidated Statements of Comprehensive Income, along with other software-related expenses. For the three- and six-month periods ended June 30, 2020, software expense included $8 million and $15 million of hosting fees that would have previously been included in outside processing fee expense.         Capitalized software, stated at cost less accumulated amortization, includes purchased software, capitalizable application development costs associated with internally developed software and cloud computing arrangements, including capitalizable implementation costs associated with hosting arrangements that are service contracts. Amortization, computed on the straight-line method, is charged to software expense in the Consolidated Statements of Comprehensive Income over the estimated useful life of the software, generally 5 years, or the term of the hosting arrangement for implementation costs related to service contracts.         Cloud computing arrangements include software as a service (SaaS), platform as a service (PaaS), infrastructure as a service (IaaS) and other similar hosting arrangements. The Corporation primarily utilizes SaaS and IaaS arrangements.         Capitalized implementation costs of hosting arrangements that are service contracts were insignificant for the three- and six-month periods ended June 30, 2020. Reference Rate Reform         In March 2020, the Financial Accounting Standards Board (FASB) issued ASU No. 2020-04, “Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting,” (ASU 2020-04), to provide temporary optional guidance to ease the potential accounting burden of reference rate reform. ASU 2020-04 is effective for eligible contract modifications from January 1, 2020 through December 31, 2022. Approximately 72 percent of the Corporation’s loans at June 30, 2020 were tied to the London Interbank Offered Rate (LIBOR). The Corporation uses interest rate swaps to convert variable-LIBOR rate loans to fixed rates for approximately 11 percent of the loan portfolio. Additional contracts with exposure to LIBOR include swaps converting fixed-rate long-term debt to variable LIBOR rates. The Corporation adopted the provisions of ASU 2020-04 for loan contract modifications as of January 1, 2020 and for all existing hedging relationships as of that date or entered into in the first quarter of 2020.

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- Definition The entire disclosure for the basis of presentation and significant accounting policies concepts. Basis of presentation describes the underlying basis used to prepare the financial statements (for example, US Generally Accepted Accounting Principles, Other Comprehensive Basis of Accounting, IFRS). Accounting policies describe all significant accounting policies of the reporting entity. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -URI http://asc.fasb.org/topic&trid=2122369 + Details Name: us-gaap_BasisOfPresentationAndSignificantAccountingPoliciesTextBlock Namespace Prefix: us-gaap_ Data Type: nonnum:textBlockItemType Balance Type: na Period Type: duration

v3.20.2

Fair Value Measurements	6 Months Ended
	Jun. 30, 2020
Fair Value Disclosures [Abstract]
Fair Value Measurements	FAIR VALUE MEASUREMENTS The Corporation utilizes fair value measurements to record fair value adjustments to certain assets and liabilities and to determine fair value disclosures. The determination of fair values of financial instruments often requires the use of estimates. In cases where quoted market values in an active market are not available, the Corporation uses present value techniques and other valuation methods to estimate the fair values of its financial instruments. These valuation methods require considerable judgment and the resulting estimates of fair value can be significantly affected by the assumptions made and methods used. Investment securities available-for-sale, derivatives, deferred compensation plans and equity securities with readily determinable fair values (primarily money market mutual funds) are recorded at fair value on a recurring basis. Additionally, from time to time, the Corporation may be required to record other assets and liabilities at fair value on a nonrecurring basis, such as nonaccrual loans and loans classified as TDRs, other real estate (primarily foreclosed property), nonmarketable equity securities and certain other assets and liabilities. These nonrecurring fair value adjustments typically involve write-downs of individual assets or application of lower of cost or fair value accounting. Refer to Note 1 to the consolidated financial statements in the Corporation's Annual Report on Form 10-K for the year ended December 31, 2019 for further information about the fair value hierarchy, descriptions of the valuation methodologies and key inputs used to measure financial assets and liabilities recorded at fair value, as well as a description of the methods and significant assumptions used to estimate fair value disclosures for financial instruments not recorded at fair value in their entirety on a recurring basis. Assets and Liabilities Recorded at Fair Value on a Recurring Basis The following tables present the recorded amount of assets and liabilities measured at fair value on a recurring basis as of June 30, 2020 and December 31, 2019. (in millions) Total Level 1 Level 2 Level 3 June 30, 2020 Deferred compensation plan assets $ 92    $ 92    $ —    $ —    Equity securities 50    50    —    —    Investment securities available-for-sale: U.S. Treasury and other U.S. government agency securities 2,852    2,852    —    —    Residential mortgage-backed securities (a) 9,907    —    9,907    —    Total investment securities available-for-sale 12,759    2,852    9,907    —    Derivative assets: Interest rate contracts 649    —    605    44    Energy derivative contracts 271    —    271    —    Foreign exchange contracts 15    —    15    —    Total derivative assets 935    —    891    44    Total assets at fair value $ 13,836    $ 2,994    $ 10,798    $ 44    Derivative liabilities: Interest rate contracts $ 73    $ —    $ 73    $ —    Energy derivative contracts 263    —    263    —    Foreign exchange contracts 15    —    15    —    Total derivative liabilities 351    —    351    —    Deferred compensation plan liabilities 92    92    —    —    Total liabilities at fair value $ 443    $ 92    $ 351    $ —    December 31, 2019 Deferred compensation plan assets $ 95    $ 95    $ —    $ —    Equity securities 54    54    —    —    Investment securities available-for-sale: U.S. Treasury and other U.S. government agency securities 2,792    2,792    —    —    Residential mortgage-backed securities (a) 9,606    —    9,606    —    Total investment securities available-for-sale 12,398    2,792    9,606    —    Derivative assets: Interest rate contracts 211    —    189    22    Energy derivative contracts 96    —    96    —    Foreign exchange contracts 10    —    10    —    Total derivative assets 317    —    295    22    Total assets at fair value $ 12,864    $ 2,941    $ 9,901    $ 22    Derivative liabilities: Interest rate contracts $ 39    $ —    $ 39    $ —    Energy derivative contracts 92    —    92    —    Foreign exchange contracts 10    —    10    —    Total derivative liabilities 141    —    141    —    Deferred compensation plan liabilities 95    95    —    —    Total liabilities at fair value $ 236    $ 95    $ 141    $ —    (a)Issued and/or guaranteed by U.S. government agencies or U.S. government-sponsored enterprises.         There were no transfers of assets or liabilities recorded at fair value on a recurring basis into or out of Level 3 fair value measurements during each of the three- and six-month periods ended June 30, 2020 and 2019. The following table summarizes the changes in Level 3 assets and liabilities measured at fair value on a recurring basis for the three- and six-month periods ended June 30, 2020 and 2019. Net Realized/Unrealized Gains (Losses) (Pretax) Recorded in Earnings (a) Balance  at Beginning of Period Balance at End of Period Payments, Sales and Redemptions (in millions) Realized Unrealized Three Months Ended June 30, 2020 Derivative assets: Interest rate contracts $ 43    $ —    $ 1    $ —    $ 44    Three Months Ended June 30, 2019 Derivative assets: Interest rate contracts $ 14    $ —    $ 7    $ —    $ 21    Six Months Ended June 30, 2020 Derivative assets: Interest rate contracts $ 22    $ —    $ 22    $ —    $ 44    Six Months Ended June 30, 2019 Derivative assets: Interest rate contracts $ 9    $ —    $ 12    $ —    $ 21    (a)Realized and unrealized gains and losses due to changes in fair value are recorded in other noninterest income on the Consolidated Statements of Comprehensive Income. Assets and Liabilities at Fair Value on a Nonrecurring Basis The Corporation may be required to record certain assets and liabilities at fair value on a nonrecurring basis. These include assets that are recorded at the lower of cost or fair value, and were recognized at fair value since it was less than cost at the end of the period. The following table presents assets recorded at fair value on a nonrecurring basis at June 30, 2020 and December 31, 2019. No liabilities were recorded at fair value on a nonrecurring basis at June 30, 2020 and December 31, 2019. (in millions) Level 3 June 30, 2020 Loans: Commercial $ 146    Total assets at fair value $ 146    December 31, 2019 Loans: Commercial $ 70    Total assets at fair value $ 70    Level 3 assets recorded at fair value on a nonrecurring basis at June 30, 2020 and December 31, 2019 included both nonaccrual loans and TDRs for which a specific allowance was established based on the fair value of collateral. The unobservable inputs were the additional adjustments applied by management to the appraised values to reflect such factors as non-current appraisals and revisions to estimated time to sell. These adjustments are determined based on qualitative judgments made by management on a case-by-case basis and are not quantifiable inputs, although they are used in the determination of fair value. Estimated Fair Values of Financial Instruments Not Recorded at Fair Value on a Recurring Basis The Corporation typically holds the majority of its financial instruments until maturity and thus does not expect to realize many of the estimated fair value amounts disclosed. The disclosures also do not include estimated fair value amounts for items that are not defined as financial instruments, but which have significant value. These include such items as core deposit intangibles, the future earnings potential of significant customer relationships and the value of trust operations and other fee generating businesses. The Corporation believes the imprecision of an estimate could be significant. The carrying amount and estimated fair value of financial instruments not recorded at fair value in their entirety on a recurring basis on the Corporation’s Consolidated Balance Sheets are as follows:   Carrying Amount Estimated Fair Value (in millions) Total Level 1 Level 2 Level 3 June 30, 2020 Assets Cash and due from banks $ 1,048    $ 1,048    $ 1,048    $ —    $ —    Interest-bearing deposits with banks 12,263    12,263    12,263    —    —    Loans held-for-sale 11    11    —    11    —    Total loans, net of allowance for loan losses (a) 52,439    52,273    —    —    52,273    Customers’ liability on acceptances outstanding 2    2    2    —    —    Restricted equity investments 269    269    269    —    —    Nonmarketable equity securities (b) 5    10    Liabilities Demand deposits (noninterest-bearing) 35,582    35,582    —    35,582    —    Interest-bearing deposits 29,482    29,482    —    29,482    —    Customer certificates of deposit 2,656    2,662    —    2,662    —    Total deposits 67,720    67,726    —    67,726    —    Short-term borrowings 752    752    752    —    —    Acceptances outstanding 2    2    2    —    —    Medium- and long-term debt 6,521    6,465    —    6,465    —    Credit-related financial instruments (81)   (81)   —    —    (81)   December 31, 2019 Assets Cash and due from banks $ 973    $ 973    $ 973    $ —    $ —    Interest-bearing deposits with banks 4,845    4,845    4,845    —    —    Loans held-for-sale 6    6    —    6    —    Total loans, net of allowance for loan losses (a) 49,732    49,975    —    —    49,975    Customers’ liability on acceptances outstanding 2    2    2    —    —    Restricted equity investments 248    248    248    —    —    Nonmarketable equity securities (b) 5    10    Liabilities Demand deposits (noninterest-bearing) 27,382    27,382    —    27,382    —    Interest-bearing deposits 26,802    26,802    —    26,802    —    Certificates of deposit 2,978    2,968    —    2,968    —    Other time deposits 133    133    —    133    —    Total deposits 57,295    57,285    —    57,285    —    Short-term borrowings 71    71    71    —    —    Acceptances outstanding 2    2    2    —    —    Medium- and long-term debt 7,269    7,316    —    7,316    —    Credit-related financial instruments (57)   (57)   —    —    (57)   (a)Included $146 million and $70 million of loans recorded at fair value on a nonrecurring basis at June 30, 2020 and December 31, 2019, respectively. (b)Certain investments that are measured at fair value using the net asset value have not been classified in the fair value hierarchy. The fair value amounts presented in the table are intended to permit reconciliation of the fair value hierarchy to the amounts presented in the Consolidated Balance Sheets.

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- Definition The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258 + Details Name: us-gaap_FairValueDisclosuresTextBlock Namespace Prefix: us-gaap_ Data Type: nonnum:textBlockItemType Balance Type: na Period Type: duration

v3.20.2

Investment Securities	6 Months Ended
	Jun. 30, 2020
Investments, Debt and Equity Securities [Abstract]
Investment Securities	INVESTMENT SECURITIES A summary of the Corporation’s investment securities follows: (in millions) Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value June 30, 2020 Investment securities available-for-sale: U.S. Treasury and other U.S. government agency securities $ 2,747    $ 105    $ —    $ 2,852    Residential mortgage-backed securities (a) 9,641    266    —    9,907    Total investment securities available-for-sale $ 12,388    $ 371    $ —    $ 12,759    December 31, 2019 Investment securities available-for-sale: U.S. Treasury and other U.S. government agency securities $ 2,745    $ 47    $ —    $ 2,792    Residential mortgage-backed securities (a) 9,568    66    28    9,606    Total investment securities available-for-sale $ 12,313    $ 113    $ 28    $ 12,398    (a)Issued and/or guaranteed by U.S. government agencies or U.S. government-sponsored enterprises. A summary of the Corporation’s investment securities in an unrealized loss position as of June 30, 2020 and December 31, 2019 follows:   Temporarily Impaired   Less than 12 Months 12 Months or more Total (in millions) Fair Value Unrealized Losses Fair Value Unrealized Losses Fair Value Unrealized Losses June 30, 2020 Residential mortgage-backed securities (a) $ 1    $ —    $ —    $ —    $ 1    $ —    Total temporarily impaired securities $ 1    $ —    $ —    $ —    $ 1    $ —    December 31, 2019 Residential mortgage-backed securities (a) $ 1,494    $ 7    $ 1,906    $ 21    $ 3,400    $ 28    Total temporarily impaired securities $ 1,494    $ 7    $ 1,906    $ 21    $ 3,400    $ 28    (a)Issued and/or guaranteed by U.S. government agencies or U.S. government-sponsored enterprises. Unrealized losses resulted from changes in market interest rates and liquidity. The Corporation’s portfolio is comprised of securities issued or guaranteed by the U.S. government or government-sponsored enterprises. As such, it is expected that the securities would not be settled at a price less than the amortized cost of the investments. Further, the Corporation does not intend to sell the investments, and it is not more likely than not that it will be required to sell the investments before recovery of amortized costs. Interest receivable on investment securities totaled $19 million at June 30, 2020 and $20 million at December 31, 2019 and was included in accrued income and other assets on the Consolidated Balance Sheets. Sales, calls and write-downs of investment securities available-for-sale resulted in the following gains and losses recorded in net securities gains (losses) on the Consolidated Statements of Comprehensive Income, computed based on the adjusted cost of the specific security. Three Months Ended June 30, Six Months Ended June 30, (in millions) 2020 2019 2020 2019 Securities gains $ 1    $ —    $ 1    $ —    Securities losses —    —    (1)   (8)   Net securities gains (losses) $ 1    $ —    $ —    $ (8)   The following table summarizes the amortized cost and fair values of debt securities by contractual maturity. Securities with multiple maturity dates are classified in the period of final maturity. Expected maturities will differ from contractual maturities because borrowers may have the right to call or prepay obligations with or without call or prepayment penalties. (in millions) June 30, 2020 Amortized Cost Fair Value Contractual maturity Within one year $ 780    $ 796    After one year through five years 2,115    2,212    After five years through ten years 872    898    After ten years 8,621    8,853    Total investment securities $ 12,388    $ 12,759    Included in the contractual maturity distribution in the table above were residential mortgage-backed securities with a total amortized cost of $9.6 billion and a fair value of $9.9 billion. The actual cash flows of mortgage-backed securities may differ as borrowers of the underlying loans may exercise prepayment options. At June 30, 2020, investment securities with a carrying value of $5.7 billion were pledged where permitted or required by law, including $5.2 billion pledged to the Federal Home Loan Bank (FHLB) as collateral for potential future borrowings of approximately $5.0 billion and $506 million to secure $432 million of liabilities, primarily public and other deposits of state and local government agencies as well as derivative instruments. For information on FHLB borrowings, refer to Note 7.

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- Definition The entire disclosure for investments in certain debt and equity securities. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 320 -URI http://asc.fasb.org/subtopic&trid=2209399 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 946 -SubTopic 320 -URI http://asc.fasb.org/subtopic&trid=2324412 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -URI http://asc.fasb.org/topic&trid=2196928 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 940 -SubTopic 320 -URI http://asc.fasb.org/subtopic&trid=2176304 + Details Name: us-gaap_InvestmentsInDebtAndMarketableEquitySecuritiesAndCertainTradingAssetsDisclosureTextBlock Namespace Prefix: us-gaap_ Data Type: nonnum:textBlockItemType Balance Type: na Period Type: duration

v3.20.2

Credit Quality And Allowance For Credit Losses	6 Months Ended
	Jun. 30, 2020
Credit Quality And Allowance For Credit Losses [Abstract]
Credit Quality And Allowance For Credit Losses	CREDIT QUALITY AND ALLOWANCE FOR CREDIT LOSSES The following table presents an aging analysis of the amortized cost basis of loans. Loans Past Due and Still Accruing       (in millions) 30-59 Days 60-89  Days 90 Days or More Total Nonaccrual Loans Current Loans (a) Total  Loans June 30, 2020 Business loans: Commercial $ 48    $ 53    $ 24    $ 125    $ 200    $ 33,501    $ 33,826    Real estate construction: Commercial Real Estate business line (b) 16    —    —    16    $ —    3,531    3,547    Other business lines (c) —    3    —    3    —    402    405    Total real estate construction 16    3    —    19    —    3,933    3,952    Commercial mortgage: Commercial Real Estate business line (b) 1    9    —    10    $ 3    2,279    2,292    Other business lines (c) 25    2    6    33    18    7,582    7,633    Total commercial mortgage 26    11    6    43    21    9,861    9,925    Lease financing —    —    —    —    1    588    589    International —    —    5    5    —    1,099    1,104    Total business loans 90    67    35    192    222    48,982    49,396    Retail loans: Residential mortgage 27    9    —    36    24    1,826    1,886    Consumer: Home equity 12    1    —    13    21    1,635    1,669    Other consumer 1    —    6    7    —    488    495    Total consumer 13    1    6    20    21    2,123    2,164    Total retail loans 40    10    6    56    45    3,949    4,050    Total loans $ 130    $ 77    $ 41    $ 248    $ 267    $ 52,931    $ 53,446    December 31, 2019 Business loans: Commercial $ 27    $ 7    $ 17    $ 51    $ 148    $ 31,274    $ 31,473    Real estate construction: Commercial Real Estate business line (b) 6    —    —    6    —    3,038    3,044    Other business lines (c) —    7    —    7    —    404    411    Total real estate construction 6    7    —    13    —    3,442    3,455    Commercial mortgage: Commercial Real Estate business line (b) 9    —    —    9    2    2,165    2,176    Other business lines (c) 16    18    9    43    12    7,328    7,383    Total commercial mortgage 25    18    9    52    14    9,493    9,559    Lease financing 1    —    —    1    —    587    588    International —    5    —    5    —    1,004    1,009    Total business loans 59    37    26    122    162    45,800    46,084    Retail loans: Residential mortgage 15    2    —    17    20    1,808    1,845    Consumer: Home equity 4    5    —    9    17    1,685    1,711    Other consumer 2    3    —    5    —    724    729    Total consumer 6    8    —    14    17    2,409    2,440    Total retail loans 21    10    —    31    37    4,217    4,285    Total loans $ 80    $ 47    $ 26    $ 153    $ 199    $ 50,017    $ 50,369    (a)Includes $4.5 billion of loans with deferred payments not considered past due in accordance with the Coronavirus Aid, Relief, and Economic Security Act (CARES Act) at June 30, 2020. (b)Primarily loans to real estate developers. (c)Primarily loans secured by owner-occupied real estate. The following table presents loans by credit quality indicator (CQI) and vintage year. CQI is based on internal risk ratings assigned to each business loan at the time of approval and subjected to subsequent reviews, generally at least annually, and to pools of retail loans with similar risk characteristics. Vintage year is the year of origination or major modification. June 30, 2020 December 31, 2019 Vintage Year (in millions) 2020 2019 2018 2017 2016 Prior Revolvers Revolvers Converted to Term Total Total Business loans: Commercial: Pass (a) $ 5,029    (b) $ 2,673    $ 1,876    $ 1,259    $ 572    $ 966    $ 18,708    $ 16    $ 31,099    $ 29,785    Criticized (c) 30    305    239    147    104    205    1,695    2    2,727    1,688    Total commercial 5,059    2,978    2,115    1,406    676    1,171    20,403    18    33,826    31,473    Real estate construction Pass (a) 127    878    1,293    795    458    218    152    —    3,921    3,424    Criticized (c) —    2    4    24    —    1    —    —    31    31    Total real estate construction 127    880    1,297    819    458    219    152    —    3,952    3,455    Commercial mortgage Pass (a) 1,058    1,713    1,220    1,254    915    2,790    499    —    9,449    9,262    Criticized (c) 31    96    32    47    47    215    8    —    476    297    Total commercial mortgage 1,089    1,809    1,252    1,301    962    3,005    507    —    9,925    9,559    Lease financing Pass (a) 63    131    84    56    17    213    —    —    564    579    Criticized (c) 1    18    3    2    1    —    —    —    25    9    Total lease financing 64    149    87    58    18    213    —    —    589    588    International Pass (a) 272    185    129    13    3    75    374    —    1,051    972    Criticized (c) 5    —    —    10    8    2    28    —    53    37    Total international 277    185    129    23    11    77    402    —    1,104    1,009    Total business loans 6,616    6,001    4,880    3,607    2,125    4,685    21,464    18    49,396    46,084    Retail loans: Residential mortgage Pass (a) 355    251    149    305    255    538    —    —    1,853    1,823    Criticized (c) —    —    5    4    3    21    —    —    33    22    Total residential mortgage 355    251    154    309    258    559    —    —    1,886    1,845    Consumer: Home equity Pass (a) —    —    —    —    —    19    1,544    82    1,645    1,682    Criticized (c) —    —    —    —    —    1    17    6    24    29    Total home equity —    —    —    —    —    20    1,561    88    1,669    1,711    Other consumer Pass (a) 13    79    19    4    6    58    306    —    485    722    Criticized (c) —    1    3    —    —    —    6    —    10    7    Total other consumer 13    80    22    4    6    58    312    —    495    729    Total consumer 13    80    22    4    6    78    1,873    88    2,164    2,440    Total retail loans 368    331    176    313    264    637    1,873    88    4,050    4,285    Total loans $ 6,984    $ 6,332    $ 5,056    $ 3,920    $ 2,389    $ 5,322    $ 23,337    $ 106    $ 53,446    $ 50,369    (a)Includes all loans not included in the categories of special mention, substandard or nonaccrual. (b)Includes $3.8 billion of Small Business Administration Paycheck Protection Program (PPP) loans at June 30, 2020. (c)Includes loans with an internal rating of special mention, substandard loans for which the accrual of interest has not been discontinued and nonaccrual loans. Special mention loans have potential credit weaknesses that deserve management’s close attention, such as loans to borrowers who may be experiencing financial difficulties that may result in deterioration of repayment prospects from the borrower at some future date. Accruing substandard loans have a well-defined weakness, or weaknesses, such as loans to borrowers who may be experiencing losses from operations or inadequate liquidity of a degree and duration that jeopardizes the orderly repayment of the loan. Substandard loans are also distinguished by the distinct possibility of loss in the future if these weaknesses are not corrected. Nonaccrual loans are loans for which the accrual of interest has been discontinued. For further information regarding nonaccrual loans, refer to the Nonperforming Assets subheading in Note 1 - Basis of Presentation and Accounting Policies - on page F-51 in the Corporation's 2019 Annual Report. These categories are generally consistent with the "special mention" and "substandard" categories as defined by regulatory authorities. A minority of nonaccrual loans are consistent with the "doubtful" category. Loan interest receivable totaled $132 million and $172 million at June 30, 2020 and December 31, 2019, respectively, and was included in accrued income and other assets on the Consolidated Balance Sheets. Allowance for Credit Losses The following table details the changes in the allowance for credit losses.   2020 2019 (in millions) Business Loans Retail Loans Total Business Loans Retail Loans Total Three Months Ended June 30 Balance at beginning of period: Allowance for loan losses $ 861    $ 55    $ 916    $ 608    $ 39    $ 647    Allowance for credit losses on lending-related commitments 52    10    62    27    3    30    Allowance for credit losses 913    65    978    635    42    677    Loan charge-offs (56)   (1)   (57)   (43)   (1)   (44)   Recoveries on loans previously charged-off 6    1    7    10    1    11    Net loan charge-offs (50)   —    (50)   (33)   —    (33)   Provision for credit losses: Provision for loan losses 132    9    141    43    —    43    Provision for credit losses on lending-related commitments (2)   (1)   (3)   1    —    1    Provision for credit losses 130    8    138    44    —    44    Balance at end of period: Allowance for loan losses 943    64    1,007    618    39    657    Allowance for credit losses on lending-related commitments 50    9    59    28    3    31    Allowance for credit losses $ 993    $ 73    $ 1,066    $ 646    $ 42    $ 688    Six Months Ended June 30 Balance at beginning of period Allowance for loan losses $ 601    $ 36    $ 637    $ 627    $ 44    $ 671    Allowance for credit losses on lending-related commitments 28    3    31    26    4    30    Allowance for credit losses 629    39    668    653    48    701    Cumulative effect of change in accounting principle (42)   25    (17)   —    —    —    Loan charge-offs (143)   (3)   (146)   (62)   (2)   (64)   Recoveries on loans previously charged-off 11    1    12    18    2    20    Net loan charge-offs (132)   (2)   (134)   (44)   —    (44)   Provision for credit losses: Provision for loan losses 516    5    521    35    (5)   30    Provision for credit losses on lending-related commitments 22    6    28    2    (1)   1    Provision for credit losses 538    11    549    37    (6)   31    Balance at end of period: Allowance for loan losses 943    64    1,007    618    39    657    Allowance for credit losses on lending-related commitments 50    9    59    28    3    31    Allowance for credit losses $ 993    $ 73    $ 1,066    $ 646    $ 42    $ 688    Allowance for loan losses as a percentage of total loans 1.91  % 1.59  % 1.88  % 1.30  % 0.89  % 1.27  % Allowance for loan losses as a percentage of total loans excluding PPP loans 2.07  % n/a 2.03  % n/a n/a n/a Allowance for credit losses as a percentage of total loans 2.01  % 1.82  % 1.99  % 1.36  % 0.96  % 1.33  % Allowance for credit losses as a percentage of total loans excluding PPP loans 2.18  % n/a 2.15  % n/a n/a n/a n/a - not applicable Nonaccrual Loans The following table presents additional information regarding nonaccrual loans. No interest income was recognized on nonaccrual loans for the three- and six-month periods ended June 30, 2020 and 2019, respectively. (in millions) Nonaccrual Loans with No Related Allowance Nonaccrual Loans with Related Allowance Total Nonaccrual Loans June 30, 2020 Business loans: Commercial $ 32    $ 168    $ 200    Commercial mortgage: Commercial Real Estate business line (a) 2    1    3    Other business lines (b) 6    12    18    Total commercial mortgage 8    13    21    Lease financing —    1    1    Total business loans 40    182    222    Retail loans: Residential mortgage 24    —    24    Consumer: Home equity 21    —    21    Total retail loans 45    —    45    Total nonaccrual loans $ 85    $ 182    $ 267    December 31, 2019 Business loans: Commercial $ 29    $ 119    $ 148    Commercial mortgage: Commercial Real Estate business line (a) 2    —    2    Other business lines (b) 1    11    12    Total commercial mortgage 3    11    14    Total business loans 32    130    162    Retail loans: Residential mortgage 20    —    20    Consumer: Home equity 17    —    17    Total retail loans 37    —    37    Total nonaccrual loans $ 69    $ 130    $ 199    (a)Primarily loans to real estate developers. (b)Primarily loans secured by owner-occupied real estate. Foreclosed Properties Foreclosed properties totaled $11 million at both June 30, 2020 and December 31, 2019. There were no retail loans secured by residential real estate properties in process of foreclosure included in nonaccrual loans at June 30, 2020 and December 31, 2019. Troubled Debt Restructurings The following table details the amortized cost basis at June 30, 2020 and 2019 of loans considered to be TDRs that were restructured during the three- and six-month periods ended June 30, 2020 and 2019, by type of modification. In cases of loans with more than one type of modification, the loans were categorized based on the most significant modification. 2020 2019 Type of Modification Type of Modification (in millions) Principal Deferrals (a) Interest Rate Reductions Total Modifications Principal Deferrals (a) Interest Rate Reductions Total Modifications Three Months Ended June 30, Home equity (b) $ —    $ —    $ —    $ —    $ 1    $ 1    Total loans $ —    $ —    $ —    $ —    $ 1    $ 1    Six Months Ended June 30, Business loans: Commercial $ 16    $ —    $ 16    $ 11    $ —    $ 11    Commercial mortgage: Other business lines (c) 1    —    $ 1    1    —    1    Total business loans 17    —    17    12    —    12    Retail loans: Consumer: Home equity (b) —    —    —    —    1    1    Total loans $ 17    $ —    $ 17    $ 12    $ 1    $ 13    (a)Primarily represents loan balances where terms were extended by more than an insignificant time period, typically more than 180 days, at or above contractual interest rates. Also includes commercial loans restructured in bankruptcy. (b)Includes bankruptcy loans for which the court has discharged the borrower's obligation and the borrower has not reaffirmed the debt. (c)Primarily loans secured by owner-occupied real estate. The Corporation charges interest on principal balances outstanding during deferral periods. Additionally, none of the modifications involved forgiveness of principal. At June 30, 2020 and December 31, 2019, commitments to lend additional funds to borrowers whose terms have been modified in TDRs totaled $2 million and $3 million, respectively. On an ongoing basis, the Corporation monitors the performance of modified loans to their restructured terms. The allowance for loan losses continues to be reassessed on the basis of an individual evaluation of the loan. For principal deferrals, incremental deterioration in the credit quality of the loan, represented by a downgrade in the risk rating of the loan, for example, due to missed interest payments or a reduction of collateral value, is considered a subsequent default. For interest rate reductions, a subsequent payment default is defined in terms of delinquency, when a principal or interest payment is 90 days past due. Of the TDRs modified during the twelve-month periods ended June 30, 2020 and 2019, principal deferrals totaled $6 million and $15 million in the three- and six-month periods ended June 30, 2020, respectively compared to none in the comparable periods in 2019. There were no subsequent defaults of interest rate reductions during either of the three- and six-month periods ended June 30, 2020 and 2019.

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- Definition The entire disclosure for financing receivable. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -URI http://asc.fasb.org/subtopic&trid=2196772 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 20 -URI http://asc.fasb.org/subtopic&trid=2196816 + Details Name: us-gaap_FinancingReceivablesTextBlock Namespace Prefix: us-gaap_ Data Type: nonnum:textBlockItemType Balance Type: na Period Type: duration

v3.20.2

Derivative And Credit-Related Financial Instruments	6 Months Ended
	Jun. 30, 2020
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative And Credit-Related Financial Instruments	DERIVATIVE AND CREDIT-RELATED FINANCIAL INSTRUMENTS In the normal course of business, the Corporation enters into various transactions involving derivative and credit-related financial instruments to manage exposure to fluctuations in interest rate, foreign currency and other market risks and to meet the financing needs of customers (customer-initiated derivatives). These financial instruments involve, to varying degrees, elements of market and credit risk. Market and credit risk are included in the determination of fair value. Market risk is the potential loss that may result from movements in interest rates, foreign currency exchange rates or energy commodity prices that cause an unfavorable change in the value of a financial instrument. The Corporation manages this risk by establishing monetary exposure limits and monitoring compliance with those limits. Market risk inherent in interest rate and energy contracts entered into on behalf of customers is mitigated by taking offsetting positions, except in those circumstances when the amount, tenor and/or contract rate level results in negligible economic risk, whereby the cost of purchasing an offsetting contract is not economically justifiable. The Corporation mitigates most of the inherent market risk in foreign exchange contracts entered into on behalf of customers by taking offsetting positions and manages the remainder through individual foreign currency position limits and aggregate value-at-risk limits. These limits are established annually and positions are monitored quarterly. Market risk inherent in derivative instruments held or issued for risk management purposes is typically offset by changes in the fair value of the assets or liabilities being hedged. Credit risk is the possible loss that may occur in the event of nonperformance by the counterparty to a financial instrument. The Corporation attempts to minimize credit risk arising from customer-initiated derivatives by evaluating the creditworthiness of each customer, adhering to the same credit approval process used for traditional lending activities and obtaining collateral as deemed necessary. Derivatives with dealer counterparties are either cleared through a clearinghouse or settled directly with a single counterparty. For derivatives settled directly with dealer counterparties, the Corporation utilizes counterparty risk limits and monitoring procedures as well as master netting arrangements and bilateral collateral agreements to facilitate the management of credit risk. Master netting arrangements effectively reduce credit risk by permitting settlement of positive and negative positions and offset cash collateral held with the same counterparty on a net basis. Bilateral collateral agreements require daily exchange of cash or highly rated securities issued by the U.S. Treasury or other U.S. government entities to collateralize amounts due to either party. At June 30, 2020, counterparties with bilateral collateral agreements deposited $216 million of cash with the Corporation to secure the fair value of contracts in an unrealized gain position, and the Corporation had pledged $56 million of marketable investment securities and posted $30 million of cash as collateral for contracts in an unrealized loss position. For those counterparties not covered under bilateral collateral agreements, collateral is obtained, if deemed necessary, based on the results of management’s credit evaluation of the counterparty. Collateral varies, but may include cash, investment securities, accounts receivable, equipment or real estate. Included in the fair value of derivative instruments are credit valuation adjustments reflecting counterparty credit risk. These adjustments are determined by applying a credit spread for the counterparty or the Corporation, as appropriate, to the total expected exposure of the derivative. There were no derivative instruments with credit-risk-related contingent features that were in a liability position at June 30, 2020. Derivative Instruments Derivative instruments utilized by the Corporation are negotiated over-the-counter and primarily include swaps, caps and floors, forward contracts and options, each of which may relate to interest rates, energy commodity prices or foreign currency exchange rates. Swaps are agreements in which two parties periodically exchange cash payments based on specified indices applied to a specified notional amount until a stated maturity. Caps and floors are agreements which entitle the buyer to receive cash payments based on the difference between a specified reference rate or price and an agreed strike rate or price, applied to a specified notional amount until a stated maturity. Forward contracts are over-the-counter agreements to buy or sell an asset at a specified future date and price. Options are similar to forward contracts except the purchaser has the right, but not the obligation, to buy or sell the asset during a specified period or at a specified future date. Over-the-counter contracts are tailored to meet the needs of the counterparties involved and, therefore, contain a greater degree of credit risk and liquidity risk than exchange-traded contracts, which have standardized terms and readily available price information. The Corporation reduces exposure to market and liquidity risks from over-the-counter derivative instruments entered into for risk management purposes, and transactions entered into to mitigate the market risk associated with customer-initiated transactions, by taking offsetting positions with investment grade domestic and foreign financial institutions and subjecting counterparties to credit approvals, limits and collateral monitoring procedures similar to those used in making other extensions of credit. In addition, certain derivative contracts executed bilaterally with a dealer counterparty in the over-the-counter market are cleared through a clearinghouse, whereby the clearinghouse becomes the counterparty to the transaction. The following table presents the composition of the Corporation’s derivative instruments held or issued for risk management purposes or in connection with customer-initiated and other activities at June 30, 2020 and December 31, 2019. The table excludes commitments and warrants accounted for as derivatives.   June 30, 2020 December 31, 2019     Fair Value   Fair Value (in millions) Notional/ Contract Amount (a) Gross Derivative Assets Gross Derivative Liabilities Notional/ Contract Amount (a) Gross Derivative Assets Gross Derivative Liabilities Risk management purposes Derivatives designated as hedging instruments Interest rate contracts: Swaps - fair value - receive fixed/pay floating $ 2,650    $ —    $ —    $ 3,325    $ —    $ —    Swaps - cash flow - receive fixed/pay floating 5,550    —    —    4,550    —    —    Derivatives used as economic hedges Foreign exchange contracts: Spot, forwards and swaps 330    1    2    330    —    2    Total risk management purposes 8,530    1    2    8,205    —    2    Customer-initiated and other activities Interest rate contracts: Caps and floors written 601    —    1    671    —    —    Caps and floors purchased 601    1    —    671    —    —    Swaps 20,039    648    72    16,485    211    39    Total interest rate contracts 21,241    649    73    17,827    211    39    Energy contracts: Caps and floors written 439    —    46    477    —    23    Caps and floors purchased 439    46    —    477    23    —    Swaps 2,137    225    217    2,135    73    69    Total energy contracts 3,015    271    263    3,089    96    92    Foreign exchange contracts: Spot, forwards, options and swaps 968    14    13    1,013    10    8    Total customer-initiated and other activities 25,224    934    349    21,929    317    139    Total gross derivatives $ 33,754    $ 935    $ 351    $ 30,134    $ 317    $ 141    Amounts offset in the Consolidated Balance Sheets: Netting adjustment - Offsetting derivative assets/liabilities (54)   (54)   (63)   (63)   Netting adjustment - Cash collateral received/posted (214)   (28)   (11)   (12)   Net derivatives included in the Consolidated Balance Sheets (b) 667    269    243    66    Amounts not offset in the Consolidated Balance Sheets: Marketable securities pledged under bilateral collateral agreements —    (53)   —    (21)   Net derivatives after deducting amounts not offset in the Consolidated Balance Sheets $ 667    $ 216    $ 243    $ 45    (a)Notional or contractual amounts, which represent the extent of involvement in the derivatives market, are used to determine the contractual cash flows required in accordance with the terms of the agreement. These amounts are typically not exchanged, significantly exceed amounts subject to credit or market risk and are not reflected in the Consolidated Balance Sheets. (b)Net derivative assets are included in accrued income and other assets and net derivative liabilities are included in accrued expenses and other liabilities on the Consolidated Balance Sheets. Included in the fair value of net derivative assets and net derivative liabilities are credit valuation adjustments reflecting counterparty credit risk and credit risk of the Corporation. The fair value of net derivative assets included credit valuation adjustments for counterparty credit risk of $25 million and $9 million at June 30, 2020 and December 31, 2019, respectively. Risk Management The Corporation's derivative instruments used for managing interest rate risk currently comprise swaps converting fixed-rate long-term debt to variable rates and variable-rate loans to fixed rates. The following table details the effects of fair value hedging on the Consolidated Statements of Comprehensive Income. Interest on Medium- and Long-Term Debt   Three Months Ended June 30, Six Months Ended June 30, (in millions) 2020 2019 2020 2019 Total interest on medium- and long-term debt (a) $ 19    $ 51    $ 59    $ 102    Fair value hedging relationships: Interest rate contracts: Hedged items 28    26    58    52    Derivatives designated as hedging instruments (12)   —    (18)   1    (a) Includes the effects of hedging.         For information on accumulated net gains on cash flow hedges, refer to Note 8.         The following table summarizes the expected weighted average remaining maturity of the notional amount of risk management interest rate swaps, the carrying amount of the related hedged items and the weighted average interest rates associated with amounts expected to be received or paid on interest rate swap agreements as of June 30, 2020 and December 31, 2019. Cash flow swaps - receive fixed/pay floating rate on variable-rate loans: (dollar amounts in millions) June 30, 2020 December 31, 2019 Derivative notional amount $ 5,550    $ 4,550    Weighted average:    Remaining maturity (in years) 2.8    3.0       Receive rate 1.87  % 1.94  %    Pay rate (a) 0.17    1.71    (a)Variable rates paid on receive fixed swaps designated as cash flow hedges are based on one-month LIBOR rates in effect at June 30, 2020 and December 31, 2019. Fair value swaps - receive fixed/pay floating rate on medium- and long-term debt: (dollar amounts in millions) June 30, 2020 December 31, 2019 Derivative notional amount $ 2,650    $ 3,325    Carrying value of hedged items (a) 2,971    3,469    Weighted average:    Remaining maturity (in years) 5.1    4.6       Receive rate 3.68  % 3.44  %    Pay rate (b) 1.54    2.80    (a)Included $322 million and $146 million of cumulative hedging adjustments at June 30, 2020 and December 31, 2019, respectively, which included $6 million and $7 million, respectively, of hedging adjustment on a discontinued hedging relationship. (b)Variable rates paid on receive fixed swaps designated as fair value hedges are based on one- and six-month LIBOR rates in effect at June 30, 2020 and December 31, 2019. Foreign exchange rate risk arises from changes in the value of certain assets and liabilities denominated in foreign currencies. The Corporation employs spot and forward contracts in addition to swap contracts to manage exposure to these and other risks. These instruments are used as economic hedges, and net gains or losses are included in other noninterest income in the Consolidated Statements of Comprehensive Income. Customer-Initiated and Other The Corporation enters into derivative transactions at the request of customers and generally takes offsetting positions with dealer counterparties to mitigate the inherent market risk. Income primarily results from the spread between the customer derivative and the offsetting dealer position. For customer-initiated foreign exchange contracts where offsetting positions have not been taken, the Corporation manages the remaining inherent market risk through individual foreign currency position limits and aggregate value-at-risk limits. These limits are established annually and reviewed quarterly. For those customer-initiated derivative contracts which were not offset or where the Corporation holds a position within the limits described above, the Corporation recognized no significant gains or losses in other noninterest income in the Consolidated Statements of Comprehensive Income for both the three- and six-month periods ended June 30, 2020 and 2019. Fair values of customer-initiated and other derivative instruments represent the net unrealized gains or losses on such contracts and are recorded in the Consolidated Balance Sheets. Changes in fair value are recognized in the Consolidated Statements of Comprehensive Income. The net gains recognized in income on customer-initiated derivative instruments, net of the impact of offsetting positions, were as follows. Three Months Ended June 30, Six Months Ended June 30, (in millions) Location of Gain 2020 2019 2020 2019 Interest rate contracts Other noninterest income $ 8    $ 6    $ 16    $ 12    Energy contracts Other noninterest income 2    2    3    3    Foreign exchange contracts Foreign exchange income 9    11    20    22    Total   $ 19    $ 19    $ 39    $ 37    Credit-Related Financial Instruments The Corporation issues off-balance sheet financial instruments in connection with commercial and consumer lending activities. The Corporation’s credit risk associated with these instruments is represented by the contractual amounts indicated in the following table. (in millions) June 30, 2020 December 31, 2019 Unused commitments to extend credit: Commercial and other $ 22,588    $ 23,681    Bankcard, revolving check credit and home equity loan commitments 3,275    3,180    Total unused commitments to extend credit $ 25,863    $ 26,861    Standby letters of credit $ 3,185    $ 3,320    Commercial letters of credit 19    18    The Corporation maintains an allowance to cover current expected credit losses on lending-related commitments, including unused commitments to extend credit, letters of credit and financial guarantees. The allowance for credit losses on lending-related commitments, included in accrued expenses and other liabilities on the Consolidated Balance Sheets, was $59 million and $31 million at June 30, 2020 and December 31, 2019, respectively. Unused Commitments to Extend Credit Commitments to extend credit are legally binding agreements to lend to a customer, provided there is no violation of any condition established in the contract. These commitments generally have fixed expiration dates or other termination clauses and may require payment of a fee. Since many commitments expire without being drawn upon, the total contractual amount of commitments does not necessarily represent future cash requirements of the Corporation. Commercial and other unused commitments are primarily variable rate commitments. The allowance for credit losses on lending-related commitments included $47 million at June 30, 2020 and $25 million at December 31, 2019 for current expected credit losses on the Corporation’s unused commitments to extend credit. Standby and Commercial Letters of Credit Standby letters of credit represent conditional obligations of the Corporation which guarantee the performance of a customer to a third party. Standby letters of credit are primarily issued to support public and private borrowing arrangements, including commercial paper, bond financing and similar transactions. Commercial letters of credit are issued to finance foreign or domestic trade transactions. These contracts expire in decreasing amounts through the year 2028. The Corporation may enter into participation arrangements with third parties that effectively reduce the maximum amount of future payments which may be required under standby and commercial letters of credit. These risk participations covered $163 million and $161 million, respectively, of the $3.2 billion and $3.3 billion standby and commercial letters of credit outstanding at June 30, 2020 and December 31, 2019, respectively. The carrying value of the Corporation’s standby and commercial letters of credit, included in accrued expenses and other liabilities on the Consolidated Balance Sheets, totaled $34 million at June 30, 2020, including $22 million in deferred fees and $12 million in the allowance for credit losses on lending-related commitments. At December 31, 2019, the comparable amounts were $32 million, $26 million and $6 million, respectively. The following table presents a summary of criticized standby and commercial letters of credit at June 30, 2020 and December 31, 2019. The Corporation's criticized list is generally consistent with the Special Mention, Substandard and Doubtful categories defined by regulatory authorities. The Corporation manages credit risk through underwriting, periodically reviewing and approving its credit exposures using Board committee approved credit policies and guidelines. (dollar amounts in millions) June 30, 2020 December 31, 2019 Total criticized standby and commercial letters of credit $ 83    $ 44    As a percentage of total outstanding standby and commercial letters of credit 2.6  % 1.3  % Other Credit-Related Financial Instruments The Corporation enters into credit risk participation agreements, under which the Corporation assumes credit exposure associated with a borrower’s performance related to certain interest rate derivative contracts. The Corporation is not a party to the interest rate derivative contracts and only enters into these credit risk participation agreements in instances in which the Corporation is also a party to the related loan participation agreements for such borrowers. The Corporation manages credit risk on credit risk participation agreements by monitoring the creditworthiness of the borrowers, based on the normal credit review process as if the Corporation had entered into the derivative instruments directly with the borrowers. The notional amount of such credit risk participation agreements reflects the pro-rata share of the derivative instrument, consistent with the Corporation's share of the related participated loan. As of June 30, 2020 and December 31, 2019, the total notional amount of the credit risk participation agreements was approximately $1.1 billion and $786 million, respectively, and the fair value was $3 million at June 30, 2020 and insignificant at December 31, 2019. The maximum estimated exposure to these agreements, as measured by projecting a maximum value of the guaranteed derivative instruments, assuming 100 percent default by all obligors on the maximum values, was $76 million and $20 million at June 30, 2020 and December 31, 2019, respectively. In the event of default, the lead bank has the ability to liquidate the assets of the borrower, in which case the lead bank would be required to return a percentage of the recouped assets to the participating banks. As of June 30, 2020, the weighted average remaining maturity of outstanding credit risk participation agreements was 4.7 years.

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- Definition The entire disclosure for derivative instruments and hedging activities including, but not limited to, risk management strategies, non-hedging derivative instruments, assets, liabilities, revenue and expenses, and methodologies and assumptions used in determining the amounts. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -URI http://asc.fasb.org/topic&trid=2229140 + Details Name: us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosureTextBlock Namespace Prefix: us-gaap_ Data Type: nonnum:textBlockItemType Balance Type: na Period Type: duration

v3.20.2

Variable Interest Entities (VIEs)	6 Months Ended
	Jun. 30, 2020
Variable Interest Entity, Not Primary Beneficiary, Disclosures [Abstract]
Variable Interest Entities (VIEs)	VARIABLE INTEREST ENTITIES (VIEs) The Corporation evaluates its interest in certain entities to determine if these entities meet the definition of a VIE and whether the Corporation is the primary beneficiary and should consolidate the entity based on the variable interests it held both at inception and when there is a change in circumstances that requires a reconsideration. The Corporation holds ownership interests in funds in the form of limited partnerships or limited liability companies (LLCs) investing in affordable housing projects that qualify for the low-income housing tax credit (LIHTC). The Corporation also directly invests in limited partnerships and LLCs which invest in community development projects, which generate similar tax credits to investors (other tax credit entities). As an investor, the Corporation obtains income tax credits and deductions from the operating losses of these tax credit entities. These tax credit entities meet the definition of a VIE; however, the Corporation is not the primary beneficiary of the entities, as the general partner or the managing member has both the power to direct the activities that most significantly impact the economic performance of the entities and the obligation to absorb losses or the right to receive benefits that could be significant to the entities. The Corporation accounts for its interests in LIHTC entities using the proportional amortization method. Ownership interests in other tax credit entities are accounted for under either the cost or equity method. Exposure to loss as a result of the Corporation's involvement in LIHTC entities and other tax credit entities at June 30, 2020 was limited to $451 million and $10 million, respectively. Investment balances, including all legally binding commitments to fund future investments, are included in accrued income and other assets on the Consolidated Balance Sheets. A liability is recognized in accrued expenses and other liabilities on the Consolidated Balance Sheets for all legally binding unfunded commitments to fund tax credit entities ($173 million at June 30, 2020). Amortization and other write-downs of LIHTC investments are presented on a net basis as a component of the provision for income taxes on the Consolidated Statements of Comprehensive Income, while amortization and write-downs of other tax credit investments are recorded in other noninterest income. The income tax credits and deductions are recorded as a reduction of income tax expense and a reduction of federal income taxes payable. The Corporation provided no financial or other support that was not contractually required to any of the above VIEs during the six months ended June 30, 2020 and 2019. The following table summarizes the impact of these tax credit entities on the Corporation’s Consolidated Statements of Comprehensive Income. Three Months Ended June 30, Six Months Ended June 30, (in millions) 2020 2019 2020 2019 Other noninterest income: Amortization of other tax credit investments $ —    $ —    $ —    $ 1    Provision for income taxes: Amortization of LIHTC investments 17    17    34    32    Low income housing tax credits (16)   (15)   (32)   (30)   Other tax benefits related to tax credit entities (3)   (4)   (7)   (7)   Total provision for income taxes $ (2)   $ (2)   $ (5)   $ (5)   For further information on the Corporation’s consolidation policy, see Note 1 to the consolidated financial statements in the Corporation's 2019 Annual Report.

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- Definition The entire disclosure for a variable interest entity (VIE), including but not limited to, judgments and assumptions in determining whether to consolidate and in identifying the primary beneficiary, gain (loss) recognized on the initial consolidation of the VIE, terms of arrangements, amounts and classification of the VIE's assets and liabilities, and the entity's maximum exposure to loss. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 810 -URI http://asc.fasb.org/topic&trid=2197479 + Details Name: us-gaap_VariableInterestEntityDisclosureTextBlock Namespace Prefix: us-gaap_ Data Type: nonnum:textBlockItemType Balance Type: na Period Type: duration

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- References No definition available. + Details Name: us-gaap_VariableInterestEntityNotPrimaryBeneficiaryDisclosuresAbstract Namespace Prefix: us-gaap_ Data Type: xbrli:stringItemType Balance Type: na Period Type: duration

v3.20.2

Medium- And Long-Term Debt	6 Months Ended
	Jun. 30, 2020
Debt Disclosure [Abstract]
Medium- And Long-Term Debt	Medium- and long-term debt is summarized as follows: (in millions) June 30, 2020 December 31, 2019 Parent company Subordinated notes: 3.80% subordinated notes due 2026 (a) $ 284    $ 264    Medium- and long-term notes: 3.70% notes due 2023 (a) 917    884    4.00% notes due 2029 (a) 647    587    Total medium- and long-term notes 1,564    1,471    Total parent company 1,848    1,735    Subsidiaries Subordinated notes: 4.00% subordinated notes due 2025 (a) 383    360    7.875% subordinated notes due 2026 (a) 213    202    Total subordinated notes 596    562    Medium- and long-term notes: 2.50% notes due 2020 (a) —    674    2.50% notes due 2024 (a) 527    498    Total medium- and long-term notes 527    1,172    FHLB advances: Floating-rate based on FHLB auction rate due 2026 2,800    2,800    Floating-rate based on FHLB auction rate due 2028 750    1,000    Total FHLB advances 3,550    3,800    Total subsidiaries 4,673    5,534    Total medium- and long-term debt $ 6,521    $ 7,269    (a)The fixed interest rates on these notes have been swapped to a variable rate and designated in a hedging relationship. Accordingly, carrying value has been adjusted to reflect the change in the fair value of the debt as a result of changes in the benchmark rate.         Subordinated notes with remaining maturities greater than one year qualify as Tier 2 capital.         Comerica Bank (the Bank), a wholly-owned subsidiary of the Corporation, is a member of the FHLB, which provides short- and long-term funding to its members through advances collateralized by real estate-related assets. The interest rates on the FHLB advances resets between four and eight weeks, based on the FHLB auction rate. At June 30, 2020, the weighted-average rate on the FHLB advances was 0.31%. Each note may be prepaid in full, without penalty, at each scheduled reset date. Borrowing capacity is contingent on the amount of collateral available to be pledged to the FHLB. At June 30, 2020, $18.3 billion of real estate-related loans and $5.2 billion of investment securities were pledged to the FHLB as collateral for outstanding short- and long-term advances of $750 million and $3.6 billion, respectively, with an additional capacity for potential future borrowings of approximately $10.1 billion.         Unamortized debt issuance costs deducted from the carrying amount of medium- and long-term debt totaled $11 million at June 30, 2020 and $12 million at December 31, 2019.

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- Definition The entire disclosure for long-term debt. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -URI http://asc.fasb.org/topic&trid=2208564 + Details Name: us-gaap_LongTermDebtTextBlock Namespace Prefix: us-gaap_ Data Type: nonnum:textBlockItemType Balance Type: na Period Type: duration

v3.20.2

Accumulated Other Comprehensive Income (Loss)	6 Months Ended
	Jun. 30, 2020
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Accumulated Other Comprehensive Loss	ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) The following table presents a reconciliation of the changes in the components of accumulated other comprehensive income (loss) and details the components of other comprehensive income (loss) for the six months ended June 30, 2020 and 2019, including the amount of income tax expense (benefit) allocated to each component of other comprehensive income (loss). Six Months Ended June 30, (in millions) 2020 2019 Accumulated net unrealized gains on investment securities: Balance at beginning of period, net of tax $ 65    $ (138)   Net unrealized holding gains arising during the period 286    229    Less: Provision for income taxes 68    54    Net unrealized holding gains arising during the period, net of tax 218    175    Less: Net realized losses included in net securities losses —    (8)   Less: Benefit for income taxes —    (2)   Reclassification adjustment for net securities losses included in net income, net of tax —    (6)   Change in net unrealized gains on investment securities, net of tax 218    181    Balance at end of period, net of tax $ 283    $ 43    Accumulated net gains on cash flow hedges: Balance at beginning of period, net of tax $ 34    $ —    Net cash flow hedge gains arising during the period 233    51    Less: Provision for income taxes 56    12    Change in net cash flow hedge gains arising during the period, net of tax 177    39    Less: Net cash flow hedge gains (losses) included in interest and fees on loans 22    (1)   Less: Provision for income taxes 7    —    Reclassification adjustment for net cash flow hedge gains (losses) included in net income, net of tax 15    (1)   Change in net cash flow hedge gains, net of tax 162    40    Balance at end of period, net of tax (a) $ 196    $ 40    Accumulated defined benefit pension and other postretirement plans adjustment: Balance at beginning of period, net of tax $ (334)   $ (471)   Amortization of actuarial net loss 31    21    Amortization of prior service credit (14)   (13)   Amounts recognized in other noninterest expenses 17    8    Less: Provision for income taxes 4    2    Change in defined benefit pension and other postretirement plans adjustment, net of tax 13    6    Balance at end of period, net of tax $ (321)   $ (465)   Total accumulated other comprehensive income (loss) at end of period, net of tax $ 158    $ (382)   (a)The Corporation expects to reclassify $73 million of net gains, net of tax, from accumulated other comprehensive income to earnings over the next twelve months if interest yield curves and notional amounts remain at June 30, 2020 levels.

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- Definition The entire disclosure for comprehensive income, which includes, but is not limited to, 1) the amount of income tax expense or benefit allocated to each component of other comprehensive income, including reclassification adjustments, 2) the reclassification adjustments for each classification of other comprehensive income and 3) the ending accumulated balances for each component of comprehensive income. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -URI http://asc.fasb.org/topic&trid=2134417 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03(21)) -URI http://asc.fasb.org/extlink&oid=120395209&loc=SL114868664-224227 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 220 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-04(23)) -URI http://asc.fasb.org/extlink&oid=120399700&loc=SL114874048-224260 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 220 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-04(19)) -URI http://asc.fasb.org/extlink&oid=120400993&loc=SL114874131-224263 + Details Name: us-gaap_ComprehensiveIncomeNoteTextBlock Namespace Prefix: us-gaap_ Data Type: nonnum:textBlockItemType Balance Type: na Period Type: duration

v3.20.2

Net Income Per Common Share	6 Months Ended
	Jun. 30, 2020
Earnings Per Share [Abstract]
Net (Loss) Income Per Common Share	NET INCOME PER COMMON SHARE Basic and diluted net income per common share are presented in the following table. Three Months Ended June 30, Six Months Ended June 30, (in millions, except per share data) 2020 2019 2020 2019 Basic and diluted Net income $ 113    $ 298    $ 48    $ 637    Less: Income allocated to participating securities 1    1    1    3    Net income attributable to common share $ 112    $ 297    $ 47    $ 634    Basic average common shares 139    152    140    155    Basic net income per common share $ 0.81    $ 1.95    $ 0.34    $ 4.10    Basic average common shares 139    152    140    155    Dilutive common stock equivalents: Net effect of the assumed exercise of stock awards —    1    1    1    Diluted average common shares 139    153    141    156    Diluted net income per common share $ 0.80    $ 1.94    $ 0.34    $ 4.06    The following average shares related to outstanding options to purchase shares of common stock were not included in the computation of diluted net income per common share because the options were anti-dilutive for the period. Three Months Ended June 30, Six Months Ended June 30, 2020 2019 2020 2019 Average outstanding options 2,056,133    470,162    1,633,078    446,610    Range of exercise prices $39.10 - $95.25 $79.01 - $95.25 $39.10 - $95.25 $79.01 - $95.25 In May 2020, the Corporation issued and sold 400,000 depositary shares, each representing a 1/100th ownership interest in a share of 5.625% Fixed-Rate Reset Non-Cumulative Perpetual Preferred Stock, Series A, without par value, with a liquidation preference of $100,000 per share (equivalent of $1,000 per depositary share). Holders of the depositary shares will be entitled to all proportional rights and preferences of the Series A preferred stock (including dividend, voting, redemption and liquidation rights). The $400 million issuance yielded $395 million in proceeds net of underwriting discounts and offering expenses. Dividends on the Series A preferred stock will accrue on a non-cumulative basis and will be payable in arrears when, as and if authorized by the Corporation’s board of directors or a duly authorized committee of the board and declared by the Corporation, on the first day of January, April, July, and October of each year, commencing on October 1, 2020. Under the terms of the Series A preferred stock, the ability of the Corporation to pay dividends on, make distributions with respect to, or to repurchase, redeem or acquire its common stock or any other stock ranking on parity with or junior to the Series A preferred stock, is subject to restrictions in the event that the Corporation does not declare and either pay or set aside a sum sufficient for payment of dividends on the Series A Preferred Stock for the immediately preceding dividend period. The Series A preferred stock is perpetual and has no maturity date, but is redeemable at specified times subject to regulatory considerations.

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- Definition The entire disclosure for earnings per share. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 260 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=109243012&loc=SL65017193-207537 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 260 -SubTopic 10 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 260 -URI http://asc.fasb.org/topic&trid=2144383 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 260 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3630-109257 + Details Name: us-gaap_EarningsPerShareTextBlock Namespace Prefix: us-gaap_ Data Type: nonnum:textBlockItemType Balance Type: na Period Type: duration

v3.20.2

Employee Benefit Plans	6 Months Ended
	Jun. 30, 2020
Retirement Benefits [Abstract]
Employee Benefit Plans	EMPLOYEE BENEFIT PLANS Net periodic defined benefit cost (credit) is comprised of service cost and other components of net benefit cost (credit). Service cost is included in salaries and benefits expense and other components of net benefit cost (credit) are included in other noninterest expenses on the Consolidated Statements of Comprehensive Income. For further information on the Corporation's employee benefit plans, refer to Note 17 to the consolidated financial statements in the Corporation's 2019 Annual Report. The components of net periodic benefit cost (credit) for the Corporation's qualified pension plan, non-qualified pension plan and postretirement benefit plan are as follows. Qualified Defined Benefit Pension Plan Three Months Ended June 30, Six Months Ended June 30, (in millions) 2020 2019 2020 2019 Service cost $ 8    $ 7    $ 16    $ 15    Other components of net benefit credit: Interest cost 17    20    35    40    Expected return on plan assets (42)   (41)   (85)   (83)   Amortization of prior service credit (5)   (4)   (10)   (9)   Amortization of net loss 13    8    27    17    Total other components of net benefit credit (17)   (17)   (33)   (35)   Net periodic defined benefit credit $ (9)   $ (10)   $ (17)   $ (20)   Non-Qualified Defined Benefit Pension Plan Three Months Ended June 30, Six Months Ended June 30, (in millions) 2020 2019 2020 2019 Service cost $ —    $ 1    $ 1    $ 2    Other components of net benefit cost: Interest cost 2    2    4    4    Amortization of prior service credit (2)   (2)   (4)   (4)   Amortization of net loss 2    2    4    4    Total other components of net benefit cost 2    2    4    4    Net periodic defined benefit cost $ 2    $ 3    $ 5    $ 6    Postretirement Benefit Plan Three Months Ended June 30, Six Months Ended June 30, (in millions) 2020 2019 2020 2019 Other components of net benefit credit: Interest cost $ —    $ —    $ —    $ 1    Expected return on plan assets (1)   —    (1)   (1)   Net periodic defined benefit credit $ (1)   $ —    $ (1)   $ —

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- Definition The entire disclosure for retirement benefits. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 55 -Paragraph 17 -URI http://asc.fasb.org/extlink&oid=118257860&loc=d3e4179-114921 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section S99 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=21916913&loc=d3e273930-122802 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (d)(i) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (o) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (p) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 Reference 6: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 70 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=49170846&loc=d3e28014-114942 Reference 7: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -URI http://asc.fasb.org/topic&trid=2235017 Reference 8: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 60 -Section 50 -Paragraph 3 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=6414203&loc=d3e39689-114964 Reference 9: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (d)(iv)(03) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 Reference 10: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (q) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 Reference 11: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (r)(1) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 Reference 12: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (d)(iii) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 Reference 13: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (l) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 Reference 14: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (r)(2) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 + Details Name: us-gaap_PensionAndOtherPostretirementBenefitsDisclosureTextBlock Namespace Prefix: us-gaap_ Data Type: nonnum:textBlockItemType Balance Type: na Period Type: duration

v3.20.2

Income Taxes And Tax-Related Items	6 Months Ended
	Jun. 30, 2020
Income Tax Disclosure [Abstract]
Income Taxes and Tax-Related Items	INCOME TAXES AND TAX-RELATED ITEMS At June 30, 2020, net unrecognized tax benefits were $18 million, compared to $17 million at December 31, 2019. The Corporation anticipates that it is reasonably possible that final settlement of federal and state tax issues will result in a decrease in net unrecognized tax benefits of $1 million within the next twelve months. Included in accrued expenses and other liabilities on the Consolidated Balance Sheets was a liability for tax-related interest and penalties of $6 million and $8 million on June 30, 2020 and December 31, 2019, respectively. Net deferred tax assets were $11 million at June 30, 2020, compared to $42 million at December 31, 2019, primarily driven by increases to deferred tax liabilities related to unrealized losses on investment securities available-for-sale and net hedging gains, partially offset by increases to deferred tax assets related to the allowance for loan losses and allowance for depreciation. Included in deferred tax assets at both June 30, 2020 and December 31, 2019 were $3 million of state net operating loss carryforwards, which expire between 2020 and 2029. The Corporation believes that it is more likely than not that the benefit from certain of these state net operating loss carryforwards will not be realized and, accordingly, maintained a valuation allowance of $3 million at both June 30, 2020 and December 31, 2019. The determination regarding valuation allowance was based on evidence of loss carryback capacity, projected future reversals of existing taxable temporary differences to absorb the deferred tax assets and assumptions made regarding future events. In the ordinary course of business, the Corporation enters into certain transactions that have tax consequences. From time to time, the Internal Revenue Service (IRS) or other tax jurisdictions may review and/or challenge specific interpretive tax positions taken by the Corporation with respect to those transactions. The Corporation believes its tax returns were filed based upon applicable statutes, regulations and case law in effect at the time of the transactions. The IRS or other tax jurisdictions, an administrative authority or a court, if presented with the transactions, could disagree with the Corporation’s interpretation of the tax law. Based on current knowledge and probability assessment of various potential outcomes, the Corporation believes that current tax reserves are adequate, and the amount of any potential incremental liability arising is not expected to have a material adverse effect on the Corporation’s consolidated financial condition or results of operations. Probabilities and outcomes are reviewed as events unfold, and adjustments to the reserves are made when necessary.

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- Definition The entire disclosure for income taxes. Disclosures may include net deferred tax liability or asset recognized in an enterprise's statement of financial position, net change during the year in the total valuation allowance, approximate tax effect of each type of temporary difference and carryforward that gives rise to a significant portion of deferred tax liabilities and deferred tax assets, utilization of a tax carryback, and tax uncertainties information. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 21 -URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32857-109319 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SAB Topic 11.C) -URI http://asc.fasb.org/extlink&oid=116825942&loc=d3e330215-122817 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 17 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32809-109319 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SAB TOPIC 6.I.5.Q1) -URI http://asc.fasb.org/extlink&oid=116825942&loc=d3e330036-122817 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 14 -URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32705-109319 Reference 6: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 270 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6424409&loc=d3e44925-109338 Reference 7: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -URI http://asc.fasb.org/topic&trid=2144680 Reference 8: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 30 -Section 50 -Paragraph 2 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=6424122&loc=d3e41874-109331 + Details Name: us-gaap_IncomeTaxDisclosureTextBlock Namespace Prefix: us-gaap_ Data Type: nonnum:textBlockItemType Balance Type: na Period Type: duration

v3.20.2

Contingent Liabilities	6 Months Ended
	Jun. 30, 2020
Commitments and Contingencies Disclosure [Abstract]
Contingent Liabilities	CONTINGENT LIABILITIES Legal Proceedings As previously reported in the Corporation's Form 10-K for the year ended December 31, 2019 and Form 10-Q for the period ended March 31, 2020, Comerica Bank, a wholly-owned subsidiary of the Corporation, was named in November 2011 as a third-party defendant in Butte Local Development v. Masters Group v. Comerica Bank (the case), for lender liability. The case was initially tried in January 2014, in the Montana Second District Judicial Court for Silver Bow County in Butte, Montana. On January 17, 2014, a jury found for Masters, resulting in an award against the Bank. On July 1, 2015, after an appeal filed by the Bank, the Montana Supreme Court reversed the judgment against the Bank and remanded the case for a new trial with instructions that Michigan contract law should apply and dismissing all other claims. In January 2017, the case was retried, without a jury, in the Second District Court, Silver Bow County, Montana. In November 2019, the court found the Bank breached its forbearance agreement. On January 17, 2020, the court conducted a hearing on the amount of costs and interest that Masters is entitled to recover. On June 12, 2020, the court found Masters is entitled to attorneys' fees, interest and costs. The Bank is considering its options, including additional appeals. Management believes that current reserves related to this case are adequate in the event of an adverse outcome. The Corporation and certain of its subsidiaries are subject to various other pending or threatened legal proceedings arising out of the normal course of business or operations. The Corporation believes it has meritorious defenses to the claims asserted against it in its other currently outstanding legal proceedings and, with respect to such legal proceedings, intends to continue to defend itself vigorously, litigating or settling cases according to management’s judgment as to what is in the best interests of the Corporation and its shareholders. Settlement may result from the Corporation's determination that it may be more prudent financially to settle, rather than litigate, and should not be regarded as an admission of liability. On at least a quarterly basis, the Corporation assesses its potential liabilities and contingencies in connection with outstanding legal proceedings utilizing the latest information available. On a case-by-case basis, reserves are established for those legal claims for which it is probable that a loss will be incurred either as a result of a settlement or judgment, and the amount of such loss can be reasonably estimated. The actual costs of resolving these claims may be substantially higher or lower than the amounts reserved. Based on current knowledge, and after consultation with legal counsel, management believes current reserves are adequate, and the amount of any incremental liability arising from these matters is not expected to have a material adverse effect on the Corporation’s consolidated financial condition, results of operations or cash flows. Legal fees of $5 million and $4 million were included in other noninterest expenses on the Consolidated Statements of Comprehensive Income for the three-month periods ended June 30, 2020 and 2019, respectively, and $7 million and $5 million for the six-month periods ended June 30, 2020 and 2019, respectively. For matters where a loss is not probable, the Corporation has not established legal reserves. The Corporation believes the estimate of the aggregate range of reasonably possible losses, in excess of reserves established, for all legal proceedings in which it is involved is from zero to approximately $46 million at June 30, 2020. This estimated aggregate range of reasonably possible losses is based upon currently available information for those proceedings in which the Corporation is involved, taking into account the Corporation’s best estimate of such losses for those cases for which such estimate can be made. For certain cases, the Corporation does not believe that an estimate can currently be made. The Corporation’s estimate involves significant judgment, given the varying stages of the proceedings (including the fact many are currently in preliminary stages), the existence in certain proceedings of multiple defendants (including the Corporation) whose share of liability has yet to be determined, the numerous yet-unresolved issues in many of the proceedings (including issues regarding class certification and the scope of many of the claims) and the attendant uncertainty of the various potential outcomes of such proceedings. Accordingly, the Corporation’s estimate will change from time to time, and actual losses may be more or less than the current estimate. In the event of unexpected future developments, it is possible the ultimate resolution of these matters, if unfavorable, may be material to the Corporation's consolidated financial condition, results of operations or cash flows. For information regarding income tax contingencies, refer to Note 11.

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- Definition The entire disclosure for commitments and contingencies. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 450 -URI http://asc.fasb.org/topic&trid=2127136 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 440 -URI http://asc.fasb.org/topic&trid=2144648 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 440 -SubTopic 10 -Section 50 -Paragraph 4 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=121559207&loc=d3e25336-109308 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 440 -SubTopic 10 -Section 50 -Paragraph 4 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=121559207&loc=d3e25336-109308 + Details Name: us-gaap_CommitmentsAndContingenciesDisclosureTextBlock Namespace Prefix: us-gaap_ Data Type: nonnum:textBlockItemType Balance Type: na Period Type: duration

v3.20.2

Business Segment Information	6 Months Ended
	Jun. 30, 2020
Segment Reporting [Abstract]
Segment Reporting Disclosure [Text Block]	BUSINESS SEGMENT INFORMATION The Corporation has strategically aligned its operations into three major business segments: the Commercial Bank, the Retail Bank and Wealth Management. These business segments are differentiated based on the type of customer and the related products and services provided. In addition to the three major business segments, the Finance Division is also reported as a segment. Business segment results are produced by the Corporation’s internal management accounting system. This system measures financial results based on the internal business unit structure of the Corporation. The performance of the business segments is not comparable with the Corporation's consolidated results and is not necessarily comparable with similar information for any other financial institution. Additionally, because of the interrelationships of the various segments, the information presented is not indicative of how the segments would perform if they operated as independent entities. The management accounting system assigns balance sheet and income statement items to each business segment using certain methodologies, which are regularly reviewed and refined. From time to time, the Corporation may make reclassifications among the segments to more appropriately reflect management's current view of the segments, and methodologies may be modified as the management accounting system is enhanced and changes occur in the organizational structure and/or product lines. For comparability purposes, amounts in all periods are based on business unit structure and methodologies in effect at June 30, 2020. The following discussion provides information about the activities of each business segment. A discussion of the financial results and the factors impacting performance can be found in the section entitled "Business Segments" in the financial review. The Commercial Bank meets the needs of small and middle market businesses, multinational corporations and governmental entities by offering various products and services including commercial loans and lines of credit, deposits, cash management, capital market products, international trade finance, letters of credit, foreign exchange management services and loan syndication services. The Retail Bank includes a full range of personal financial services, consisting of consumer lending, consumer deposit gathering and mortgage loan origination. This business segment offers a variety of consumer products including deposit accounts, installment loans, credit cards, student loans, home equity lines of credit and residential mortgage loans. Wealth Management offers products and services consisting of fiduciary services, private banking, retirement services, investment management and advisory services, investment banking and brokerage services. This business segment also offers the sale of annuity products, as well as life, disability and long-term care insurance products. The Finance segment includes the Corporation’s securities portfolio and asset and liability management activities. This segment is responsible for managing the Corporation’s funding, liquidity and capital needs, performing interest sensitivity analysis and executing various strategies to manage the Corporation’s exposure to liquidity, interest rate risk and foreign exchange risk. The Other category includes the income and expense impact of equity and cash, tax benefits not assigned to specific business segments, charges of an unusual or infrequent nature that are not reflective of the normal operations of the business segments and miscellaneous other expenses of a corporate nature. For further information on the methodologies which form the basis for these results refer to Note 22 to the consolidated financial statements in the Corporation's 2019 Annual Report. Business segment financial results are as follows: Commercial Bank Retail Bank Wealth Management Finance Other Total (dollar amounts in millions) Three Months Ended June 30, 2020 Earnings summary: Net interest income (expense) $ 402    $ 120    $ 40    $ (95)   $ 4    $ 471    Provision for credit losses 117    5    16    —    —    138    Noninterest income 144    24    66    11    2    247    Noninterest expenses 207    155    73    1    4    440    Provision (benefit) for income taxes 47    (4)   3    (20)   1    27    Net income (loss) $ 175    $ (12)   $ 14    $ (65)   $ 1    $ 113    Net credit-related charge-offs $ 48    $ 1    $ 1    $ —    $ —    $ 50    Selected average balances: Assets $ 47,392    $ 3,306    $ 5,191    $ 14,500    $ 11,255    $ 81,644    Loans 45,914    2,479    5,077    —    28    53,498    Deposits 36,318    22,647    4,217    950    150    64,282    Statistical data: Return on average assets (a) 1.49  % (0.21) % 1.00  % n/m n/m 0.55  % Efficiency ratio (b) 37.67    107.15    69.86    n/m n/m 61.14    Three Months Ended June 30, 2019 Earnings summary: Net interest income (expense) $ 420    $ 146    $ 46    $ (23)   $ 14    $ 603    Provision for credit losses 52    1    (5)   —    (4)   44    Noninterest income 136    33    68    13    —    250    Noninterest expenses 195    147    67    —    15    424    Provision (benefit) for income taxes 71    7    13    (4)   —    87    Net income (loss) $ 238    $ 24    $ 39    $ (6)   $ 3    $ 298    Net credit-related charge-offs (recoveries) $ 35    $ —    $ (2)   $ —    $ —    $ 33    Selected average balances: Assets $ 45,321    $ 2,839    $ 5,071    $ 13,907    $ 4,114    $ 71,252    Loans 43,932    2,107    4,930    —    (6)   50,963    Deposits 28,251    20,649    3,740    2,174    181    54,995    Statistical data: Return on average assets (a) 2.11  % 0.44  % 3.10  % n/m n/m 1.68  % Efficiency ratio (b) 34.98    82.26    58.99    n/m n/m 49.65    (a)Return on average assets is calculated based on the greater of average assets or average liabilities and attributed equity. (b)Noninterest expenses as a percentage of the sum of net interest income and noninterest income excluding net gains (losses) from securities and a derivative contract tied to the conversion rate of Visa Class B shares. n/m – not meaningful Commercial Bank Retail Bank Wealth Management Finance Other Total (dollar amounts in millions) Six Months Ended June 30, 2020 Earnings summary: Net interest income (expense) $ 782    $ 245    $ 81    $ (139)   $ 15    $ 984    Provision for credit losses 513    8    28    —    —    549    Noninterest income 271    52    136    25    —    484    Noninterest expenses 401    304    145    1    14    865    Provision (benefit) for income taxes 27    (4)   9    (28)   2    6    Net income (loss) $ 112    $ (11)   $ 35    $ (87)   $ (1)   $ 48    Net credit-related charge-offs $ 131    $ 2    $ 1    $ —    $ —    $ 134    Selected average balances: Assets $ 45,823    $ 3,085    $ 5,134    $ 14,393    $ 9,019    $ 77,454    Loans 44,253    2,277    5,007    —    14    51,551    Deposits 33,274    21,921    4,120    1,043    166    60,524    Statistical data: Return on average assets (a) 0.49  % (0.10) % 1.34  % n/m n/m 0.12  % Efficiency ratio (b) 38.05    101.41    67.00    n/m n/m 58.80    Six Months Ended June 30, 2019 Earnings summary: Net interest income (expense) $ 832    $ 292    $ 93    $ (37)   $ 29    $ 1,209    Provision for credit losses 46    (3)   (10)   —    (2)   31    Noninterest income 272    64    132    17    3    488    Noninterest expenses 393    292    139    1    32    857    Provision (benefit) for income taxes 153    16    23    (8)   (12)   172    Net income (loss) $ 512    $ 51    $ 73    $ (13)   $ 14    $ 637    Net credit-related charge-offs (recoveries) $ 47    $ —    $ (3)   $ —    $ —    $ 44    Selected average balances: Assets $ 44,619    $ 2,826    $ 5,121    $ 13,747    $ 4,202    $ 70,515    Loans 43,241    2,105    4,983    —    (6)   50,323    Deposits 28,356    20,560    3,770    1,655    157    54,498    Statistical data: Return on average assets (a) 2.31  % 0.49  % 2.88  % n/m n/m 1.82  % Efficiency ratio (b) 35.61    81.80    61.67    n/m n/m 50.23    (a)Return on average assets is calculated based on the greater of average assets or average liabilities and attributed equity. (b)Noninterest expenses as a percentage of the sum of net interest income and noninterest income excluding net gains (losses) from securities and a derivative contract tied to the conversion rate of Visa Class B shares. n/m – not meaningful The Corporation operates in three primary markets - Texas, California and Michigan, as well as in Arizona and Florida, with select businesses operating in several other states and in Canada and Mexico. The Corporation produces market segment results for the Corporation’s three primary geographic markets as well as Other Markets. Other Markets includes Florida, Arizona, the International Finance division and businesses with a national perspective. The Finance & Other category includes the Finance segment and the Other category as previously described. Market segment results are provided as supplemental information to the business segment results and may not meet all operating segment criteria as set forth in GAAP. For comparability purposes, amounts in all periods are based on market segments and methodologies in effect at June 30, 2020. A discussion of the financial results and the factors impacting performance can be found in the section entitled "Market Segments" in the financial review. Market segment financial results are as follows: Michigan California Texas Other Markets Finance & Other Total (dollar amounts in millions) Three Months Ended June 30, 2020 Earnings summary: Net interest income (expense) $ 159    $ 176    $ 116    $ 111    $ (91)   $ 471    Provision for credit losses 40    51    31    16    —    138    Noninterest income 64    36    30    104    13    247    Noninterest expenses 139    103    91    102    5    440    Provision (benefit) for income taxes 8    13    4    21    (19)   27    Net income (loss) $ 36    $ 45    $ 20    $ 76    $ (64)   $ 113    Net credit-related charge-offs $ —    $ 4    $ 46    $ —    $ —    $ 50    Selected average balances: Assets $ 13,643    $ 18,948    $ 11,597    $ 11,732    $ 25,724    $ 81,644    Loans 13,014    18,663    11,184    10,640    (3)   53,498    Deposits 23,460    18,463    10,209    11,050    1,100    64,282    Statistical data: Return on average assets (a) 0.59  % 0.93  % 0.68  % 2.53  % n/m 0.55  % Efficiency ratio (b) 62.08    48.61    61.88    47.41    n/m 61.14    Three Months Ended June 30, 2019 Earnings summary: Net interest income (expense) $ 186    $ 208    $ 124    $ 94    $ (9)   $ 603    Provision for credit losses (10)   (4)   49    13    (4)   44    Noninterest income 72    40    34    91    13    250    Noninterest expenses 134    99    84    92    15    424    Provision (benefit) for income taxes 30    39    6    16    (4)   87    Net income (loss) $ 104    $ 114    $ 19    $ 64    $ (3)   $ 298    Net credit-related charge-offs $ —    $ 7    $ 26    $ —    $ —    $ 33    Selected average balances: Assets $ 13,239    $ 19,108    $ 11,342    $ 9,542    $ 18,021    $ 71,252    Loans 12,704    18,806    10,684    8,775    (6)   50,963    Deposits 19,816    16,314    8,668    7,842    2,355    54,995    Statistical data: Return on average assets (a) 2.01  % 2.38  % 0.69  % 2.75  % n/m 1.68  % Efficiency ratio (b) 52.04    40.07    52.86    49.36    n/m 49.65    (a)Return on average assets is calculated based on the greater of average assets or average liabilities and attributed equity. (b)Noninterest expenses as a percentage of the sum of net interest income and noninterest income excluding net gains (losses) from securities and a derivative contract tied to the conversion rate of Visa Class B shares. n/m – not meaningful. Michigan California Texas Other Markets Finance & Other Total (dollar amounts in millions) Six Months Ended June 30, 2020 Earnings summary: Net interest income (expense) $ 322    $ 358    $ 231    $ 197    $ (124)   $ 984    Provision for credit losses 64    102    321    62    —    549    Noninterest income 136    72    60    191    25    484    Noninterest expenses 279    201    175    195    15    865    Provision (benefit) for income taxes 23    30    (46)   25    (26)   6    Net income (loss) $ 92    $ 97    $ (159)   $ 106    $ (88)   $ 48    Net credit-related charge-offs $ 3    $ 15    $ 116    $ —    $ —    $ 134    Selected average balances: Assets $ 13,269    $ 18,664    $ 11,371    $ 10,754    $ 23,396    $ 77,454    Loans 12,601    18,346    10,870    9,735    (1)   51,551    Deposits 22,104    17,965    9,705    9,541    1,209    60,524    Statistical data: Return on average assets (a) 0.81  % 1.02  % (2.82) % 1.99  % n/m 0.12  % Efficiency ratio (b) 60.46    46.77    60.07    50.25    n/m 58.80    Six Months Ended June 30, 2019 Earnings summary: Net interest income (expense) $ 373    $ 411    $ 248    $ 185    $ (8)   $ 1,209    Provision for credit losses (5)   (5)   38    5    (2)   31    Noninterest income 144    80    66    178    20    488    Noninterest expenses 273    199    169    183    33    857    Provision (benefit) for income taxes 56    76    25    35    (20)   172    Net income $ 193    $ 221    $ 82    $ 140    $ 1    $ 637    Net credit-related charge-offs (recoveries) $ 4    $ 4    $ 39    $ (3)   $ —    $ 44    Selected average balances: Assets $ 13,157    $ 19,020    $ 11,128    $ 9,261    $ 17,949    $ 70,515    Loans 12,631    18,730    10,474    8,494    (6)   50,323    Deposits 19,854    16,276    8,682    7,874    1,812    54,498    Statistical data: Return on average assets (a) 1.89  % 2.35  % 1.47  % 3.06  % n/m 1.82  % Efficiency ratio (b) 52.85    40.49    53.74    50.30    n/m 50.23    (a)Return on average assets is calculated based on the greater of average assets or average liabilities and attributed equity. (b)Noninterest expenses as a percentage of the sum of net interest income and noninterest income excluding net gains (losses) from securities and a derivative contract tied to the conversion rate of Visa Class B shares. n/m – not meaningful.

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- Definition The entire disclosure for reporting segments including data and tables. Reportable segments include those that meet any of the following quantitative thresholds a) it's reported revenue, including sales to external customers and intersegment sales or transfers is 10 percent or more of the combined revenue, internal and external, of all operating segments b) the absolute amount of its reported profit or loss is 10 percent or more of the greater, in absolute amount of 1) the combined reported profit of all operating segments that did not report a loss or 2) the combined reported loss of all operating segments that did report a loss c) its assets are 10 percent or more of the combined assets of all operating segments. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 280 -SubTopic 10 -Section 50 -Paragraph 31 -URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8924-108599 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 280 -SubTopic 10 -Section 50 -Paragraph 34 -URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8981-108599 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 280 -SubTopic 10 -Section 50 -Paragraph 21 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8721-108599 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 280 -SubTopic 10 -Section 50 -Paragraph 40 -URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e9031-108599 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 280 -SubTopic 10 -Section 50 -Paragraph 32 -Subparagraph (f) -URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8933-108599 Reference 6: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 280 -SubTopic 10 -Section 50 -Paragraph 32 -Subparagraph (e) -URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8933-108599 Reference 7: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 280 -SubTopic 10 -Section 50 -Paragraph 26 -URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8844-108599 Reference 8: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 280 -SubTopic 10 -Section 50 -Paragraph 41 -URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e9038-108599 Reference 9: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 280 -SubTopic 10 -Section 50 -Paragraph 32 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8933-108599 Reference 10: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 280 -SubTopic 10 -Section 50 -Paragraph 22 -URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8736-108599 Reference 11: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 280 -SubTopic 10 -Section 50 -Paragraph 42 -URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e9054-108599 Reference 12: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 280 -SubTopic 10 -Section 50 -Paragraph 15 -URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8657-108599 Reference 13: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 280 -SubTopic 10 -Section 50 -Paragraph 21 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8721-108599 Reference 14: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 280 -URI http://asc.fasb.org/topic&trid=2134510 + Details Name: us-gaap_SegmentReportingDisclosureTextBlock Namespace Prefix: us-gaap_ Data Type: nonnum:textBlockItemType Balance Type: na Period Type: duration

v3.20.2

Revenue from Contracts with Customers	6 Months Ended
	Jun. 30, 2020
Revenue from Contract with Customer [Abstract]
Revenue from Contracts with Customers	REVENUE FROM CONTRACTS WITH CUSTOMERS Revenue from contracts with customers comprises the noninterest income earned by the Corporation in exchange for services provided to customers. The following table presents the composition of revenue from contracts with customers, segregated from other sources of noninterest income, by business segment. Commercial Bank Retail Bank Wealth Management Finance & Other Total (in millions) Three Months Ended June 30, 2020 Revenue from contracts with customers: Card fees $ 59    $ 8    $ 1    $ —    $ 68    Service charges on deposit accounts 30    11    1    —    42    Fiduciary income —    —    52    —    52    Commercial loan servicing fees (a) 4    —    —    —    4    Brokerage fees —    —    5    —    5    Other noninterest income (b) 11    2    4    —    17    Total revenue from contracts with customers 104    21    63    —    188    Other sources of noninterest income 40    3    3    13    59    Total noninterest income $ 144    $ 24    $ 66    $ 13    $ 247    Three Months Ended June 30, 2019 Revenue from contracts with customers: Card fees $ 54    $ 10    $ 1    $ —    $ 65    Service charges on deposit accounts 33    17    1    —    51    Fiduciary income —    —    52    —    52    Commercial loan servicing fees (a) 4    —    —    —    4    Brokerage fees —    —    7    —    7    Other noninterest income (b) 2    4    4    —    10    Total revenue from contracts with customers 93    31    65    —    189    Other sources of noninterest income 43    2    3    13    61    Total noninterest income $ 136    $ 33    $ 68    $ 13    $ 250    Six Months Ended June 30, 2020 Revenue from contracts with customers: Card fees $ 108    $ 17    $ 2    $ —    $ 127    Service charges on deposit accounts 62    27    2    —    91    Fiduciary income —    —    106    —    106    Commercial loan servicing fees (a) 8    —    —    —    8    Brokerage fees —    —    12    —    12    Other noninterest income (b) 15    5    9    —    29    Total revenue from contracts with customers 193    49    131    —    373    Other sources of noninterest income 78    3    5    25    111    Total noninterest income $ 271    $ 52    $ 136    $ 25    $ 484    Six Months Ended June 30, 2019 Revenue from contracts with customers: Card fees $ 107    $ 19    $ 2    $ —    $ 128    Service charges on deposit accounts 66    34    2    —    102    Fiduciary income —    —    101    —    101    Commercial loan servicing fees (a) 8    —    —    —    8    Brokerage fees —    —    14    —    14    Other noninterest income (b) 4    7    9    —    20    Total revenue from contracts with customers 185    60    128    —    373    Other sources of noninterest income 87    4    4    20    115    Total noninterest income $ 272    $ 64    $ 132    $ 20    $ 488    (a)Included in commercial lending fees on the Consolidated Statements of Comprehensive Income. (b)Excludes derivative, warrant and other miscellaneous income.         Adjustments to revenue during the three- and six-month periods ended June 30, 2020 and 2019 for refunds or credits relating to prior periods were not significant.         Revenue from contracts with customers did not generate significant contract assets and liabilities.

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- Definition The entire disclosure of revenue from contract with customer to transfer good or service and to transfer nonfinancial asset. Includes, but is not limited to, disaggregation of revenue, credit loss recognized from contract with customer, judgment and change in judgment related to contract with customer, and asset recognized from cost incurred to obtain or fulfill contract with customer. Excludes insurance and lease contracts. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 606 -URI http://asc.fasb.org/topic&trid=49130388 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 606 -SubTopic 10 -Section 50 -Paragraph 10 -URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130551-203045 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 606 -SubTopic 10 -Section 50 -Paragraph 13 -Subparagraph (b)(2) -URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130556-203045 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 606 -SubTopic 10 -Section 50 -Paragraph 12 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130554-203045 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 606 -SubTopic 10 -Section 50 -Paragraph 9 -URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130550-203045 Reference 6: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 606 -SubTopic 10 -Section 50 -Paragraph 12 -Subparagraph (e) -URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130554-203045 Reference 7: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 606 -SubTopic 10 -Section 50 -Paragraph 12 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130554-203045 Reference 8: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 606 -SubTopic 10 -Section 50 -Paragraph 12 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130554-203045 Reference 9: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 606 -SubTopic 10 -Section 50 -Paragraph 15 -URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130558-203045 Reference 10: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 606 -SubTopic 10 -Section 50 -Paragraph 12 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130554-203045 + Details Name: us-gaap_RevenueFromContractWithCustomerTextBlock Namespace Prefix: us-gaap_ Data Type: nonnum:textBlockItemType Balance Type: na Period Type: duration

v3.20.2

Basis of Presentation and Accounting Policies Basis of Presentation and Accounting Policies (Policies)	6 Months Ended
	Jun. 30, 2020
Accounting Policies [Abstract]
Allowance For Credit Losses [Policy Text Block]	Allowance for Credit Losses         The allowance for credit losses includes both the allowance for loan losses and the allowance for credit losses on lending-related commitments.         The Corporation disaggregates the loan portfolio into segments for purposes of determining the allowance for credit losses. These segments are based on the level at which the Corporation develops, documents and applies a systematic methodology to determine the allowance for credit losses. The Corporation's portfolio segments are business loans and retail loans. Business loans include the commercial, real estate construction, commercial mortgage, lease financing and international loan portfolios. Retail loans consist of residential mortgage and consumer loans, including home equity loans.         Effective January 1, 2020, the Corporation adopted the provisions of Accounting Standards Update (ASU) No. 2016-13, "Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments," commonly referred to as the current expected credit loss (CECL) model, for all financial assets, except those accounted for at fair value through net income, using the modified retrospective approach.         Under Topic 326, current expected credit losses are estimated over the contractual life of the loan portfolio, considering all available relevant information, including historical and current conditions as well as reasonable and supportable forecasts of future events. The previous accounting principle estimated probable, estimable losses inherent in the portfolio.         At adoption, the Corporation’s estimate of current expected credit losses in accordance with Topic 326 resulted in a $17 million day-one decrease in the overall allowance for credit losses, from $668 million at December 31, 2019 under the incurred loss model. The Corporation recognized a corresponding $13 million increase to retained earnings and a $4 million reduction to deferred tax assets. A similar adjustment at December 31, 2019 would have caused a 2-basis-point increase in the Common Equity Tier 1 (CET1) capital ratio. Business loans, comprising approximately 91 percent of the Corporation’s total loan portfolio at transition, consist of loans and lending arrangements with generally short contractual maturities. As a result, the allowance for credit losses for business loans decreased $42 million. The allowance for credit losses increased $25 million for retail loans, given their longer contractual maturities.         Topic 326 also requires expected credit losses on available-for-sale (AFS) debt securities to be recorded as an allowance for credit losses. For certain types of debt securities, such as U.S. Treasuries and other securities with government guarantees, entities may expect zero credit losses. The zero-loss expectation applies to all the Corporation’s securities and no allowance for credit losses was recorded on its AFS securities portfolio at transition. Allowance for Loan Losses         The allowance for loan losses is estimated on a quarterly basis and represents management’s estimates of current expected credit losses in the Corporation’s loan portfolio. Pools of loans with similar risk characteristics are collectively evaluated while loans that no longer share risk characteristics with loan pools are evaluated individually.         Collective loss estimates are determined by applying reserve factors, designed to estimate current expected credit losses, to amortized cost balances over the remaining contractual life of the collectively evaluated portfolio. Loans with similar risk characteristics are aggregated into homogeneous pools. Business loans are assigned to pools based primarily on business line and the Corporation’s internal risk rating system. For retail loans, pools are based on loan type, past due status and credit scores. Reserve factors are based on estimated probability of default for each pool, set to a default horizon based on contractual life, and loss given default. Historical estimates are calibrated to economic forecasts over the reasonable and supportable forecast period based on the projected performance of specific economic variables that statistically correlate with each of the probability of default and loss given default pools.         The calculation of current expected credit losses is inherently subjective, as it requires management to exercise judgment in determining appropriate factors used to determine the allowance. Some of the most significant factors in the quantitative allowance estimate are assigning internal risk ratings to loans, selecting the economic forecasts used to calibrate the reserve factors and determining the reasonable and supportable forecast period. •Internal Risk Ratings: Loss factors are dependent on loan risk ratings for business loans. Risk ratings are assigned at origination, based on inherent credit risk, and may be updated based on new information that becomes available, periodic reviews of credit quality, a change in borrower performance or modifications to lending agreements. •Economic Forecasts: Management selects economic variables it believes to be most relevant based on the composition of the loan portfolio and customer base, including forecasted levels of employment, gross domestic product, corporate bond and treasury spreads, industrial production levels, consumer and commercial real estate price indices as well as housing statistics. Different economic forecast scenarios ranging from more benign to more severe are evaluated each reporting period to forecast losses over the contractual life of the loan portfolio. •Forecast Period: Economic forecasts are applied over the period management believes it can estimate reasonable and supportable forecasts. Forecast periods may be adjusted in response to changes in the economic environment. To estimate losses for contractual periods that extend beyond the forecast horizon, the Corporation reverts to an average historical loss experience. The Corporation typically forecasts economic variables over a two-year horizon, followed by an immediate reversion to an average historical loss experience that generally incorporates a full economic cycle. Management reviews this methodology on at least an annual basis.         The allowance for loan losses also includes qualitative adjustments to bring the allowance to the level management believes is appropriate based on factors that have not otherwise been fully accounted for, including adjustments for foresight risk, input imprecision and model imprecision. Foresight risk reflects the inherent imprecision in forecasting economic variables, including determining the depth and duration of economic cycles and their impact to relevant economic variables. The Corporation may make qualitative adjustments based on its evaluation of different forecast scenarios and known recent events impacting relevant economic variables. Input imprecision factors address the risk that certain model inputs may not reflect all available information including (i) risk factors that have not been fully addressed in internal risk ratings, (ii) changes in lending policies and procedures, (iii) changes in the level and quality of experience held by lending management, (iv) imprecision in the risk rating system and (v) limitations in data available for certain loan portfolios. Model imprecision considers known model limitations and model updates not yet fully reflected in the quantitative estimate.          The determination of the appropriate qualitative adjustment is based on management's analysis of current and expected economic conditions and their impact to the portfolio, as well as internal credit risk movements and a qualitative assessment of the lending environment, including underwriting standards. Management recognizes the sensitivity of various assumptions made in the quantitative modeling of expected losses and may adjust reserves depending upon the level of uncertainty that currently exists in one or more assumptions.         Credit losses for loans that no longer share risk characteristics with the loan pools are estimated on an individual basis. Individual credit loss estimates are typically performed for nonaccrual loans and modified loans classified as troubled debt restructurings (TDRs) and are based on one of several methods, including the estimated fair value of the underlying collateral, observable market value of similar debt or the present value of expected cash flows. The Corporation considers certain loans to be collateral-dependent if the borrower is experiencing financial difficulty and management expects repayment for the loan to be substantially through the operation or sale of the collateral. For collateral-dependent loans, loss estimates are based on the fair value of collateral, less estimated cost to sell (if applicable). Collateral values supporting individually evaluated loans are assessed quarterly and appraisals are typically obtained at least annually.         The total allowance for loan losses is sufficient to absorb expected credit losses over the contractual life of the portfolio. Unanticipated events impacting the economy, including political instability or global events affecting the U.S. economy, could cause changes to expectations for current conditions and economic forecasts that result in an unanticipated increase in the allowance. Significant increases in current portfolio exposures or changes in credit characteristics could also increase the amount of the allowance. Such events, or others of similar nature, may result in the need for additional provision for credit losses in order to maintain an allowance that complies with credit risk and accounting policies.         Loans deemed uncollectible are charged off and deducted from the allowance. Recoveries on loans previously charged off are added to the allowance.         Credit losses are not estimated for accrued interest receivable as interest that is deemed uncollectible is written off through interest income. Allowance for Credit Losses on Lending-Related Commitments The allowance for credit losses on lending-related commitments estimates current expected credit losses on collective pools of letters of credit and unused commitments to extend credit based on reserve factors, determined in a manner similar to business loans, multiplied by a probability of draw estimate, based on historical experience and credit risk, applied to commitment amounts. The allowance for credit losses on lending-related commitments is included in accrued expenses and other liabilities on the Consolidated Balance Sheets, with the corresponding charge included in the provision for credit losses on the Consolidated Statements of Comprehensive Income.
Goodwill and Intangible Assets, Goodwill, Policy [Policy Text Block]	Goodwill         Effective January 1, 2020, the Corporation prospectively adopted the provisions of ASU No. 2017-04, “Intangibles - Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment,” (ASU 2017-04), eliminating the second step of goodwill impairment testing, under which the implied fair value of goodwill was determined as if the reporting unit were being acquired in a business combination. Under ASU 2017-04, the Corporation will compare the fair value of a reporting unit with its carrying amount and recognize an impairment charge for any amount by which the carrying amount exceeds the reporting unit’s fair value, to the extent that the loss recognized does not exceed the amount of goodwill allocated to that reporting unit. The adoption of ASU 2017-04 did not impact the Corporation’s current financial condition or results of operations.         Goodwill, included in accrued income and other assets on the Consolidated Balance Sheets, is initially recorded as the excess of the purchase price over the fair value of net assets acquired in a business combination and is subsequently evaluated at least annually for impairment. Goodwill impairment testing is performed at the reporting unit level, equivalent to a business segment or one level below. The Corporation has three reporting units: the Commercial Bank, the Retail Bank and Wealth Management.         The Corporation performs its annual evaluation of goodwill impairment in the third quarter of each year and may elect to perform a quantitative impairment analysis or first conduct a qualitative analysis to determine if a quantitative analysis is necessary. Additionally, the Corporation evaluates goodwill impairment on an interim basis if events or changes in circumstances between annual tests indicate additional testing may be warranted to determine if goodwill might be impaired. Factors considered in the assessment of the likelihood of impairment include macroeconomic conditions, industry and market considerations, stock performance of the Corporation and its peers, financial performance of the reporting units, and previous results of goodwill impairment tests, amongst other factors. Based on the results of the qualitative analysis, the Corporation determines whether a quantitative test is deemed necessary. The quantitative test compares the estimated fair value of identified reporting units with their carrying amount, including goodwill. If the estimated fair value of the reporting unit is less than the carrying value, an impairment charge would be recorded for the excess, not to exceed the amount of goodwill allocated to the reporting unit.
Internal Use Software, Policy [Policy Text Block]	Software         Effective January 1, 2020, the Corporation adopted the provisions of ASU No. 2018-15, “Intangibles - Goodwill and Other - Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract," using a prospective approach for implementation costs incurred subsequent to the adoption of the standard. Amortization expense from capitalized implementation costs of hosting arrangements that are service contracts and fees associated with the hosting elements of the arrangements, are included in software expense in the Consolidated Statements of Comprehensive Income, along with other software-related expenses. For the three- and six-month periods ended June 30, 2020, software expense included $8 million and $15 million of hosting fees that would have previously been included in outside processing fee expense.         Capitalized software, stated at cost less accumulated amortization, includes purchased software, capitalizable application development costs associated with internally developed software and cloud computing arrangements, including capitalizable implementation costs associated with hosting arrangements that are service contracts. Amortization, computed on the straight-line method, is charged to software expense in the Consolidated Statements of Comprehensive Income over the estimated useful life of the software, generally 5 years, or the term of the hosting arrangement for implementation costs related to service contracts.         Cloud computing arrangements include software as a service (SaaS), platform as a service (PaaS), infrastructure as a service (IaaS) and other similar hosting arrangements. The Corporation primarily utilizes SaaS and IaaS arrangements.         Capitalized implementation costs of hosting arrangements that are service contracts were insignificant for the three- and six-month periods ended June 30, 2020.
Financing Receivable [Policy Text Block]	Reference Rate Reform         In March 2020, the Financial Accounting Standards Board (FASB) issued ASU No. 2020-04, “Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting,” (ASU 2020-04), to provide temporary optional guidance to ease the potential accounting burden of reference rate reform. ASU 2020-04 is effective for eligible contract modifications from January 1, 2020 through December 31, 2022. Approximately 72 percent of the Corporation’s loans at June 30, 2020 were tied to the London Interbank Offered Rate (LIBOR). The Corporation uses interest rate swaps to convert variable-LIBOR rate loans to fixed rates for approximately 11 percent of the loan portfolio. Additional contracts with exposure to LIBOR include swaps converting fixed-rate long-term debt to variable LIBOR rates. The Corporation adopted the provisions of ASU 2020-04 for loan contract modifications as of January 1, 2020 and for all existing hedging relationships as of that date or entered into in the first quarter of 2020.

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- Definition Disclosure of accounting policy and method for estimating the allowance for losses on loans and lease receivables. The description may include (a) how the entity determines each element of the allowance, (b) which loans are evaluated individually and which loans are evaluated as a group, (c) how the entity determines both the allocated and unallocated portions of the allowance, (d) how the entity determines the loss factors applied to graded loans in order to develop a general allowance, and (e) what self-correcting mechanism the entity uses to reduce differences between estimated and actual losses. Also describes the policy and method for estimating the allowance for credit losses inherent in lending-related commitments, including unused commitments to extend credit, letters of credit and financial guarantees. + References No definition available. + Details Name: cma_AllowanceForCreditLossesPolicyTextBlock Namespace Prefix: cma_ Data Type: nonnum:textBlockItemType Balance Type: na Period Type: duration

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- References No definition available. + Details Name: us-gaap_AccountingPoliciesAbstract Namespace Prefix: us-gaap_ Data Type: xbrli:stringItemType Balance Type: na Period Type: duration

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- Definition Disclosure of accounting policy for financing receivable. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=121611835&loc=d3e5093-111524 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 20 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=84159169&loc=d3e10133-111534 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 20 -Section 50 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=84159169&loc=d3e10178-111534 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 9 -URI http://asc.fasb.org/extlink&oid=121611835&loc=d3e5144-111524 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 20 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=84159169&loc=d3e10149-111534 Reference 6: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 11B -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=121611835&loc=SL6953423-111524 Reference 7: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=121611835&loc=d3e5033-111524 Reference 8: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 15 -Subparagraph (b,d) -URI http://asc.fasb.org/extlink&oid=121611835&loc=d3e5212-111524 + Details Name: us-gaap_FinanceLoansAndLeasesReceivablePolicy Namespace Prefix: us-gaap_ Data Type: nonnum:textBlockItemType Balance Type: na Period Type: duration

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- Definition Disclosure of accounting policy for goodwill. This accounting policy also may address how an entity assesses and measures impairment of goodwill, how reporting units are determined, how goodwill is allocated to such units, and how the fair values of the reporting units are determined. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 20 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=121556970&loc=d3e13816-109267 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=84158767&loc=d3e18780-107790 + Details Name: us-gaap_GoodwillAndIntangibleAssetsGoodwillPolicy Namespace Prefix: us-gaap_ Data Type: nonnum:textBlockItemType Balance Type: na Period Type: duration

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- Definition Disclosure of accounting policy for costs incurred when both (1) the software is acquired, internally developed, or modified solely to meet the entity's internal needs, and (2) during the software's development or modification, no substantive plan exists or is being developed to market the software externally. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 40 -Section 30 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=118172244&loc=d3e17916-109280 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 50 -Section 25 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=16397303&loc=d3e19379-109286 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=84158767&loc=d3e18780-107790 + Details Name: us-gaap_InternalUseSoftwarePolicy Namespace Prefix: us-gaap_ Data Type: nonnum:textBlockItemType Balance Type: na Period Type: duration

v3.20.2

Fair Value Measurements (Tables)	6 Months Ended
	Jun. 30, 2020
Fair Value Disclosures [Abstract]
Assets And Liabilities Recorded At Fair Value On A Recurring Basis	The following tables present the recorded amount of assets and liabilities measured at fair value on a recurring basis as of June 30, 2020 and December 31, 2019. (in millions) Total Level 1 Level 2 Level 3 June 30, 2020 Deferred compensation plan assets $ 92    $ 92    $ —    $ —    Equity securities 50    50    —    —    Investment securities available-for-sale: U.S. Treasury and other U.S. government agency securities 2,852    2,852    —    —    Residential mortgage-backed securities (a) 9,907    —    9,907    —    Total investment securities available-for-sale 12,759    2,852    9,907    —    Derivative assets: Interest rate contracts 649    —    605    44    Energy derivative contracts 271    —    271    —    Foreign exchange contracts 15    —    15    —    Total derivative assets 935    —    891    44    Total assets at fair value $ 13,836    $ 2,994    $ 10,798    $ 44    Derivative liabilities: Interest rate contracts $ 73    $ —    $ 73    $ —    Energy derivative contracts 263    —    263    —    Foreign exchange contracts 15    —    15    —    Total derivative liabilities 351    —    351    —    Deferred compensation plan liabilities 92    92    —    —    Total liabilities at fair value $ 443    $ 92    $ 351    $ —    December 31, 2019 Deferred compensation plan assets $ 95    $ 95    $ —    $ —    Equity securities 54    54    —    —    Investment securities available-for-sale: U.S. Treasury and other U.S. government agency securities 2,792    2,792    —    —    Residential mortgage-backed securities (a) 9,606    —    9,606    —    Total investment securities available-for-sale 12,398    2,792    9,606    —    Derivative assets: Interest rate contracts 211    —    189    22    Energy derivative contracts 96    —    96    —    Foreign exchange contracts 10    —    10    —    Total derivative assets 317    —    295    22    Total assets at fair value $ 12,864    $ 2,941    $ 9,901    $ 22    Derivative liabilities: Interest rate contracts $ 39    $ —    $ 39    $ —    Energy derivative contracts 92    —    92    —    Foreign exchange contracts 10    —    10    —    Total derivative liabilities 141    —    141    —    Deferred compensation plan liabilities 95    95    —    —    Total liabilities at fair value $ 236    $ 95    $ 141    $ —    (a)Issued and/or guaranteed by U.S. government agencies or U.S. government-sponsored enterprises.
Changes In Level 3 Assets And Liabilities Measured At Fair Value On A Recurring Basis	The following table summarizes the changes in Level 3 assets and liabilities measured at fair value on a recurring basis for the three- and six-month periods ended June 30, 2020 and 2019. Net Realized/Unrealized Gains (Losses) (Pretax) Recorded in Earnings (a) Balance  at Beginning of Period Balance at End of Period Payments, Sales and Redemptions (in millions) Realized Unrealized Three Months Ended June 30, 2020 Derivative assets: Interest rate contracts $ 43    $ —    $ 1    $ —    $ 44    Three Months Ended June 30, 2019 Derivative assets: Interest rate contracts $ 14    $ —    $ 7    $ —    $ 21    Six Months Ended June 30, 2020 Derivative assets: Interest rate contracts $ 22    $ —    $ 22    $ —    $ 44    Six Months Ended June 30, 2019 Derivative assets: Interest rate contracts $ 9    $ —    $ 12    $ —    $ 21    (a)Realized and unrealized gains and losses due to changes in fair value are recorded in other noninterest income on the Consolidated Statements of Comprehensive Income.
Assets And Liabilities Recorded At Fair Value On A Nonrecurring Basis	The following table presents assets recorded at fair value on a nonrecurring basis at June 30, 2020 and December 31, 2019. No liabilities were recorded at fair value on a nonrecurring basis at June 30, 2020 and December 31, 2019. (in millions) Level 3 June 30, 2020 Loans: Commercial $ 146    Total assets at fair value $ 146    December 31, 2019 Loans: Commercial $ 70    Total assets at fair value $ 70
Estimated Fair Values Of Financial Instruments Not Recorded At Fair Value In Their Entirety On A Recurring Basis	The carrying amount and estimated fair value of financial instruments not recorded at fair value in their entirety on a recurring basis on the Corporation’s Consolidated Balance Sheets are as follows:   Carrying Amount Estimated Fair Value (in millions) Total Level 1 Level 2 Level 3 June 30, 2020 Assets Cash and due from banks $ 1,048    $ 1,048    $ 1,048    $ —    $ —    Interest-bearing deposits with banks 12,263    12,263    12,263    —    —    Loans held-for-sale 11    11    —    11    —    Total loans, net of allowance for loan losses (a) 52,439    52,273    —    —    52,273    Customers’ liability on acceptances outstanding 2    2    2    —    —    Restricted equity investments 269    269    269    —    —    Nonmarketable equity securities (b) 5    10    Liabilities Demand deposits (noninterest-bearing) 35,582    35,582    —    35,582    —    Interest-bearing deposits 29,482    29,482    —    29,482    —    Customer certificates of deposit 2,656    2,662    —    2,662    —    Total deposits 67,720    67,726    —    67,726    —    Short-term borrowings 752    752    752    —    —    Acceptances outstanding 2    2    2    —    —    Medium- and long-term debt 6,521    6,465    —    6,465    —    Credit-related financial instruments (81)   (81)   —    —    (81)   December 31, 2019 Assets Cash and due from banks $ 973    $ 973    $ 973    $ —    $ —    Interest-bearing deposits with banks 4,845    4,845    4,845    —    —    Loans held-for-sale 6    6    —    6    —    Total loans, net of allowance for loan losses (a) 49,732    49,975    —    —    49,975    Customers’ liability on acceptances outstanding 2    2    2    —    —    Restricted equity investments 248    248    248    —    —    Nonmarketable equity securities (b) 5    10    Liabilities Demand deposits (noninterest-bearing) 27,382    27,382    —    27,382    —    Interest-bearing deposits 26,802    26,802    —    26,802    —    Certificates of deposit 2,978    2,968    —    2,968    —    Other time deposits 133    133    —    133    —    Total deposits 57,295    57,285    —    57,285    —    Short-term borrowings 71    71    71    —    —    Acceptances outstanding 2    2    2    —    —    Medium- and long-term debt 7,269    7,316    —    7,316    —    Credit-related financial instruments (57)   (57)   —    —    (57)   (a)Included $146 million and $70 million of loans recorded at fair value on a nonrecurring basis at June 30, 2020 and December 31, 2019, respectively. (b)Certain investments that are measured at fair value using the net asset value have not been classified in the fair value hierarchy. The fair value amounts presented in the table are intended to permit reconciliation of the fair value hierarchy to the amounts presented in the Consolidated Balance Sheets.

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- Definition Tabular disclosure of assets and liabilities by class, including financial instruments measured at fair value that are classified in shareholders' equity, if any, that are measured at fair value on a nonrecurring basis in periods after initial recognition (for example, impaired assets). Disclosures may include, but are not limited to: (a) the fair value measurements recorded and the reasons for the measurements and (b) the level within the fair value hierarchy in which the fair value measurements are categorized in their entirety (levels 1, 2, 3). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (bbb) -URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258 + Details Name: us-gaap_FairValueAssetsMeasuredOnNonrecurringBasisTextBlock Namespace Prefix: us-gaap_ Data Type: nonnum:textBlockItemType Balance Type: na Period Type: duration

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- Definition Tabular disclosure of the fair value measurement of assets using significant unobservable inputs (Level 3), a reconciliation of the beginning and ending balances, separately presenting changes during the period attributable to the following: (1) total gains or losses for the period (realized and unrealized), segregating those gains or losses included in earnings (or changes in net assets) and gains or losses recognized in other comprehensive income (loss), and a description of where those gains or losses included in earnings (or changes in net assets) are reported in the statement of income (or activities); (2) purchases, sales, issues, and settlements (each type disclosed separately); and (3) transfers in and transfers out of Level 3 (for example, transfers due to changes in the observability of significant inputs), by class of asset. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19279-110258 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258 + Details Name: us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTextBlock Namespace Prefix: us-gaap_ Data Type: nonnum:textBlockItemType Balance Type: na Period Type: duration

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- Definition Tabular disclosure of the fair value of financial instruments, including financial assets and financial liabilities, and the measurements of those instruments, assets, and liabilities. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 11 -URI http://asc.fasb.org/extlink&oid=121572278&loc=d3e13467-108611 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258 + Details Name: us-gaap_FairValueByBalanceSheetGroupingTextBlock Namespace Prefix: us-gaap_ Data Type: nonnum:textBlockItemType Balance Type: na Period Type: duration

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- References No definition available. + Details Name: us-gaap_FairValueDisclosuresAbstract Namespace Prefix: us-gaap_ Data Type: xbrli:stringItemType Balance Type: na Period Type: duration

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- Definition Tabular disclosure of assets and liabilities, including [financial] instruments measured at fair value that are classified in stockholders' equity, if any, that are measured at fair value on a recurring basis. The disclosures contemplated herein include the fair value measurements at the reporting date by the level within the fair value hierarchy in which the fair value measurements in their entirety fall, segregating fair value measurements using quoted prices in active markets for identical assets (Level 1), significant other observable inputs (Level 2), and significant unobservable inputs (Level 3). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258 + Details Name: us-gaap_ScheduleOfFairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisTableTextBlock Namespace Prefix: us-gaap_ Data Type: nonnum:textBlockItemType Balance Type: na Period Type: duration

v3.20.2

Investment Securities (Tables)	6 Months Ended
	Jun. 30, 2020
Investments, Debt and Equity Securities [Abstract]
Summary Of Investment Securities	A summary of the Corporation’s investment securities follows: (in millions) Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value June 30, 2020 Investment securities available-for-sale: U.S. Treasury and other U.S. government agency securities $ 2,747    $ 105    $ —    $ 2,852    Residential mortgage-backed securities (a) 9,641    266    —    9,907    Total investment securities available-for-sale $ 12,388    $ 371    $ —    $ 12,759    December 31, 2019 Investment securities available-for-sale: U.S. Treasury and other U.S. government agency securities $ 2,745    $ 47    $ —    $ 2,792    Residential mortgage-backed securities (a) 9,568    66    28    9,606    Total investment securities available-for-sale $ 12,313    $ 113    $ 28    $ 12,398    (a)Issued and/or guaranteed by U.S. government agencies or U.S. government-sponsored enterprises.
Summary Of Investment Securities In Unrealized Loss Positions	A summary of the Corporation’s investment securities in an unrealized loss position as of June 30, 2020 and December 31, 2019 follows:   Temporarily Impaired   Less than 12 Months 12 Months or more Total (in millions) Fair Value Unrealized Losses Fair Value Unrealized Losses Fair Value Unrealized Losses June 30, 2020 Residential mortgage-backed securities (a) $ 1    $ —    $ —    $ —    $ 1    $ —    Total temporarily impaired securities $ 1    $ —    $ —    $ —    $ 1    $ —    December 31, 2019 Residential mortgage-backed securities (a) $ 1,494    $ 7    $ 1,906    $ 21    $ 3,400    $ 28    Total temporarily impaired securities $ 1,494    $ 7    $ 1,906    $ 21    $ 3,400    $ 28    (a)Issued and/or guaranteed by U.S. government agencies or U.S. government-sponsored enterprises.
Summary of Net Securities Gains (Losses)	Sales, calls and write-downs of investment securities available-for-sale resulted in the following gains and losses recorded in net securities gains (losses) on the Consolidated Statements of Comprehensive Income, computed based on the adjusted cost of the specific security. Three Months Ended June 30, Six Months Ended June 30, (in millions) 2020 2019 2020 2019 Securities gains $ 1    $ —    $ 1    $ —    Securities losses —    —    (1)   (8)   Net securities gains (losses) $ 1    $ —    $ —    $ (8)
Contractual Maturity Distribution Of Debt Securities	The following table summarizes the amortized cost and fair values of debt securities by contractual maturity. Securities with multiple maturity dates are classified in the period of final maturity. Expected maturities will differ from contractual maturities because borrowers may have the right to call or prepay obligations with or without call or prepayment penalties. (in millions) June 30, 2020 Amortized Cost Fair Value Contractual maturity Within one year $ 780    $ 796    After one year through five years 2,115    2,212    After five years through ten years 872    898    After ten years 8,621    8,853    Total investment securities $ 12,388    $ 12,759

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- Definition Tabular disclosure of the proceeds from sales of available-for-sale securities and the gross realized gains and gross realized losses that have been included in earnings as a result of those sales. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 9 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=121645371&loc=d3e27357-111563 + Details Name: us-gaap_ScheduleOfRealizedGainLossTableTextBlock Namespace Prefix: us-gaap_ Data Type: nonnum:textBlockItemType Balance Type: na Period Type: duration

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- Definition For all investments in an unrealized loss position, including those for which other-than-temporary impairments have not been recognized in earnings (including investments for which a portion of an other-than-temporary impairment has been recognized in other comprehensive income), a tabular disclosure of the aggregate related fair value of investments with unrealized losses and the aggregate amount of unrealized losses (that is, the amount by which amortized cost basis exceeds fair value). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=121645371&loc=d3e27290-111563 + Details Name: us-gaap_ScheduleOfUnrealizedLossOnInvestmentsTableTextBlock Namespace Prefix: us-gaap_ Data Type: nonnum:textBlockItemType Balance Type: na Period Type: duration

v3.20.2

Credit Quality And Allowance For Credit Losses (Tables)	6 Months Ended
	Jun. 30, 2020
Credit Quality And Allowance For Credit Losses [Abstract]
Aging Analysis Of Loans	The following table presents an aging analysis of the amortized cost basis of loans. Loans Past Due and Still Accruing       (in millions) 30-59 Days 60-89  Days 90 Days or More Total Nonaccrual Loans Current Loans (a) Total  Loans June 30, 2020 Business loans: Commercial $ 48    $ 53    $ 24    $ 125    $ 200    $ 33,501    $ 33,826    Real estate construction: Commercial Real Estate business line (b) 16    —    —    16    $ —    3,531    3,547    Other business lines (c) —    3    —    3    —    402    405    Total real estate construction 16    3    —    19    —    3,933    3,952    Commercial mortgage: Commercial Real Estate business line (b) 1    9    —    10    $ 3    2,279    2,292    Other business lines (c) 25    2    6    33    18    7,582    7,633    Total commercial mortgage 26    11    6    43    21    9,861    9,925    Lease financing —    —    —    —    1    588    589    International —    —    5    5    —    1,099    1,104    Total business loans 90    67    35    192    222    48,982    49,396    Retail loans: Residential mortgage 27    9    —    36    24    1,826    1,886    Consumer: Home equity 12    1    —    13    21    1,635    1,669    Other consumer 1    —    6    7    —    488    495    Total consumer 13    1    6    20    21    2,123    2,164    Total retail loans 40    10    6    56    45    3,949    4,050    Total loans $ 130    $ 77    $ 41    $ 248    $ 267    $ 52,931    $ 53,446    December 31, 2019 Business loans: Commercial $ 27    $ 7    $ 17    $ 51    $ 148    $ 31,274    $ 31,473    Real estate construction: Commercial Real Estate business line (b) 6    —    —    6    —    3,038    3,044    Other business lines (c) —    7    —    7    —    404    411    Total real estate construction 6    7    —    13    —    3,442    3,455    Commercial mortgage: Commercial Real Estate business line (b) 9    —    —    9    2    2,165    2,176    Other business lines (c) 16    18    9    43    12    7,328    7,383    Total commercial mortgage 25    18    9    52    14    9,493    9,559    Lease financing 1    —    —    1    —    587    588    International —    5    —    5    —    1,004    1,009    Total business loans 59    37    26    122    162    45,800    46,084    Retail loans: Residential mortgage 15    2    —    17    20    1,808    1,845    Consumer: Home equity 4    5    —    9    17    1,685    1,711    Other consumer 2    3    —    5    —    724    729    Total consumer 6    8    —    14    17    2,409    2,440    Total retail loans 21    10    —    31    37    4,217    4,285    Total loans $ 80    $ 47    $ 26    $ 153    $ 199    $ 50,017    $ 50,369    (a)Includes $4.5 billion of loans with deferred payments not considered past due in accordance with the Coronavirus Aid, Relief, and Economic Security Act (CARES Act) at June 30, 2020. (b)Primarily loans to real estate developers. (c)Primarily loans secured by owner-occupied real estate.
Loans By Credit Quality Indicator and Vintage Year	The following table presents loans by credit quality indicator (CQI) and vintage year. CQI is based on internal risk ratings assigned to each business loan at the time of approval and subjected to subsequent reviews, generally at least annually, and to pools of retail loans with similar risk characteristics. Vintage year is the year of origination or major modification. June 30, 2020 December 31, 2019 Vintage Year (in millions) 2020 2019 2018 2017 2016 Prior Revolvers Revolvers Converted to Term Total Total Business loans: Commercial: Pass (a) $ 5,029    (b) $ 2,673    $ 1,876    $ 1,259    $ 572    $ 966    $ 18,708    $ 16    $ 31,099    $ 29,785    Criticized (c) 30    305    239    147    104    205    1,695    2    2,727    1,688    Total commercial 5,059    2,978    2,115    1,406    676    1,171    20,403    18    33,826    31,473    Real estate construction Pass (a) 127    878    1,293    795    458    218    152    —    3,921    3,424    Criticized (c) —    2    4    24    —    1    —    —    31    31    Total real estate construction 127    880    1,297    819    458    219    152    —    3,952    3,455    Commercial mortgage Pass (a) 1,058    1,713    1,220    1,254    915    2,790    499    —    9,449    9,262    Criticized (c) 31    96    32    47    47    215    8    —    476    297    Total commercial mortgage 1,089    1,809    1,252    1,301    962    3,005    507    —    9,925    9,559    Lease financing Pass (a) 63    131    84    56    17    213    —    —    564    579    Criticized (c) 1    18    3    2    1    —    —    —    25    9    Total lease financing 64    149    87    58    18    213    —    —    589    588    International Pass (a) 272    185    129    13    3    75    374    —    1,051    972    Criticized (c) 5    —    —    10    8    2    28    —    53    37    Total international 277    185    129    23    11    77    402    —    1,104    1,009    Total business loans 6,616    6,001    4,880    3,607    2,125    4,685    21,464    18    49,396    46,084    Retail loans: Residential mortgage Pass (a) 355    251    149    305    255    538    —    —    1,853    1,823    Criticized (c) —    —    5    4    3    21    —    —    33    22    Total residential mortgage 355    251    154    309    258    559    —    —    1,886    1,845    Consumer: Home equity Pass (a) —    —    —    —    —    19    1,544    82    1,645    1,682    Criticized (c) —    —    —    —    —    1    17    6    24    29    Total home equity —    —    —    —    —    20    1,561    88    1,669    1,711    Other consumer Pass (a) 13    79    19    4    6    58    306    —    485    722    Criticized (c) —    1    3    —    —    —    6    —    10    7    Total other consumer 13    80    22    4    6    58    312    —    495    729    Total consumer 13    80    22    4    6    78    1,873    88    2,164    2,440    Total retail loans 368    331    176    313    264    637    1,873    88    4,050    4,285    Total loans $ 6,984    $ 6,332    $ 5,056    $ 3,920    $ 2,389    $ 5,322    $ 23,337    $ 106    $ 53,446    $ 50,369    (a)Includes all loans not included in the categories of special mention, substandard or nonaccrual. (b)Includes $3.8 billion of Small Business Administration Paycheck Protection Program (PPP) loans at June 30, 2020. (c)Includes loans with an internal rating of special mention, substandard loans for which the accrual of interest has not been discontinued and nonaccrual loans. Special mention loans have potential credit weaknesses that deserve management’s close attention, such as loans to borrowers who may be experiencing financial difficulties that may result in deterioration of repayment prospects from the borrower at some future date. Accruing substandard loans have a well-defined weakness, or weaknesses, such as loans to borrowers who may be experiencing losses from operations or inadequate liquidity of a degree and duration that jeopardizes the orderly repayment of the loan. Substandard loans are also distinguished by the distinct possibility of loss in the future if these weaknesses are not corrected. Nonaccrual loans are loans for which the accrual of interest has been discontinued. For further information regarding nonaccrual loans, refer to the Nonperforming Assets subheading in Note 1 - Basis of Presentation and Accounting Policies - on page F-51 in the Corporation's 2019 Annual Report. These categories are generally consistent with the "special mention" and "substandard" categories as defined by regulatory authorities. A minority of nonaccrual loans are consistent with the "doubtful" category.
Changes In The Allowance For Loan Losses	The following table details the changes in the allowance for credit losses.   2020 2019 (in millions) Business Loans Retail Loans Total Business Loans Retail Loans Total Three Months Ended June 30 Balance at beginning of period: Allowance for loan losses $ 861    $ 55    $ 916    $ 608    $ 39    $ 647    Allowance for credit losses on lending-related commitments 52    10    62    27    3    30    Allowance for credit losses 913    65    978    635    42    677    Loan charge-offs (56)   (1)   (57)   (43)   (1)   (44)   Recoveries on loans previously charged-off 6    1    7    10    1    11    Net loan charge-offs (50)   —    (50)   (33)   —    (33)   Provision for credit losses: Provision for loan losses 132    9    141    43    —    43    Provision for credit losses on lending-related commitments (2)   (1)   (3)   1    —    1    Provision for credit losses 130    8    138    44    —    44    Balance at end of period: Allowance for loan losses 943    64    1,007    618    39    657    Allowance for credit losses on lending-related commitments 50    9    59    28    3    31    Allowance for credit losses $ 993    $ 73    $ 1,066    $ 646    $ 42    $ 688    Six Months Ended June 30 Balance at beginning of period Allowance for loan losses $ 601    $ 36    $ 637    $ 627    $ 44    $ 671    Allowance for credit losses on lending-related commitments 28    3    31    26    4    30    Allowance for credit losses 629    39    668    653    48    701    Cumulative effect of change in accounting principle (42)   25    (17)   —    —    —    Loan charge-offs (143)   (3)   (146)   (62)   (2)   (64)   Recoveries on loans previously charged-off 11    1    12    18    2    20    Net loan charge-offs (132)   (2)   (134)   (44)   —    (44)   Provision for credit losses: Provision for loan losses 516    5    521    35    (5)   30    Provision for credit losses on lending-related commitments 22    6    28    2    (1)   1    Provision for credit losses 538    11    549    37    (6)   31    Balance at end of period: Allowance for loan losses 943    64    1,007    618    39    657    Allowance for credit losses on lending-related commitments 50    9    59    28    3    31    Allowance for credit losses $ 993    $ 73    $ 1,066    $ 646    $ 42    $ 688    Allowance for loan losses as a percentage of total loans 1.91  % 1.59  % 1.88  % 1.30  % 0.89  % 1.27  % Allowance for loan losses as a percentage of total loans excluding PPP loans 2.07  % n/a 2.03  % n/a n/a n/a Allowance for credit losses as a percentage of total loans 2.01  % 1.82  % 1.99  % 1.36  % 0.96  % 1.33  % Allowance for credit losses as a percentage of total loans excluding PPP loans 2.18  % n/a 2.15  % n/a n/a n/a
Changes In the Allowance For Credit Losses On Lending-Related Commitments
Nonaccrual Loans	The following table presents additional information regarding nonaccrual loans. No interest income was recognized on nonaccrual loans for the three- and six-month periods ended June 30, 2020 and 2019, respectively. (in millions) Nonaccrual Loans with No Related Allowance Nonaccrual Loans with Related Allowance Total Nonaccrual Loans June 30, 2020 Business loans: Commercial $ 32    $ 168    $ 200    Commercial mortgage: Commercial Real Estate business line (a) 2    1    3    Other business lines (b) 6    12    18    Total commercial mortgage 8    13    21    Lease financing —    1    1    Total business loans 40    182    222    Retail loans: Residential mortgage 24    —    24    Consumer: Home equity 21    —    21    Total retail loans 45    —    45    Total nonaccrual loans $ 85    $ 182    $ 267    December 31, 2019 Business loans: Commercial $ 29    $ 119    $ 148    Commercial mortgage: Commercial Real Estate business line (a) 2    —    2    Other business lines (b) 1    11    12    Total commercial mortgage 3    11    14    Total business loans 32    130    162    Retail loans: Residential mortgage 20    —    20    Consumer: Home equity 17    —    17    Total retail loans 37    —    37    Total nonaccrual loans $ 69    $ 130    $ 199    (a)Primarily loans to real estate developers. (b)Primarily loans secured by owner-occupied real estate.
Troubled Debt Restructurings By Type Of Modification	The following table details the amortized cost basis at June 30, 2020 and 2019 of loans considered to be TDRs that were restructured during the three- and six-month periods ended June 30, 2020 and 2019, by type of modification. In cases of loans with more than one type of modification, the loans were categorized based on the most significant modification. 2020 2019 Type of Modification Type of Modification (in millions) Principal Deferrals (a) Interest Rate Reductions Total Modifications Principal Deferrals (a) Interest Rate Reductions Total Modifications Three Months Ended June 30, Home equity (b) $ —    $ —    $ —    $ —    $ 1    $ 1    Total loans $ —    $ —    $ —    $ —    $ 1    $ 1    Six Months Ended June 30, Business loans: Commercial $ 16    $ —    $ 16    $ 11    $ —    $ 11    Commercial mortgage: Other business lines (c) 1    —    $ 1    1    —    1    Total business loans 17    —    17    12    —    12    Retail loans: Consumer: Home equity (b) —    —    —    —    1    1    Total loans $ 17    $ —    $ 17    $ 12    $ 1    $ 13    (a)Primarily represents loan balances where terms were extended by more than an insignificant time period, typically more than 180 days, at or above contractual interest rates. Also includes commercial loans restructured in bankruptcy. (b)Includes bankruptcy loans for which the court has discharged the borrower's obligation and the borrower has not reaffirmed the debt. (c)Primarily loans secured by owner-occupied real estate.

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v3.20.2

Derivative And Credit-Related Financial Instruments (Tables)	6 Months Ended
	Jun. 30, 2020
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule Of Derivative Instruments	The following table presents the composition of the Corporation’s derivative instruments held or issued for risk management purposes or in connection with customer-initiated and other activities at June 30, 2020 and December 31, 2019. The table excludes commitments and warrants accounted for as derivatives.   June 30, 2020 December 31, 2019     Fair Value   Fair Value (in millions) Notional/ Contract Amount (a) Gross Derivative Assets Gross Derivative Liabilities Notional/ Contract Amount (a) Gross Derivative Assets Gross Derivative Liabilities Risk management purposes Derivatives designated as hedging instruments Interest rate contracts: Swaps - fair value - receive fixed/pay floating $ 2,650    $ —    $ —    $ 3,325    $ —    $ —    Swaps - cash flow - receive fixed/pay floating 5,550    —    —    4,550    —    —    Derivatives used as economic hedges Foreign exchange contracts: Spot, forwards and swaps 330    1    2    330    —    2    Total risk management purposes 8,530    1    2    8,205    —    2    Customer-initiated and other activities Interest rate contracts: Caps and floors written 601    —    1    671    —    —    Caps and floors purchased 601    1    —    671    —    —    Swaps 20,039    648    72    16,485    211    39    Total interest rate contracts 21,241    649    73    17,827    211    39    Energy contracts: Caps and floors written 439    —    46    477    —    23    Caps and floors purchased 439    46    —    477    23    —    Swaps 2,137    225    217    2,135    73    69    Total energy contracts 3,015    271    263    3,089    96    92    Foreign exchange contracts: Spot, forwards, options and swaps 968    14    13    1,013    10    8    Total customer-initiated and other activities 25,224    934    349    21,929    317    139    Total gross derivatives $ 33,754    $ 935    $ 351    $ 30,134    $ 317    $ 141    Amounts offset in the Consolidated Balance Sheets: Netting adjustment - Offsetting derivative assets/liabilities (54)   (54)   (63)   (63)   Netting adjustment - Cash collateral received/posted (214)   (28)   (11)   (12)   Net derivatives included in the Consolidated Balance Sheets (b) 667    269    243    66    Amounts not offset in the Consolidated Balance Sheets: Marketable securities pledged under bilateral collateral agreements —    (53)   —    (21)   Net derivatives after deducting amounts not offset in the Consolidated Balance Sheets $ 667    $ 216    $ 243    $ 45    (a)Notional or contractual amounts, which represent the extent of involvement in the derivatives market, are used to determine the contractual cash flows required in accordance with the terms of the agreement. These amounts are typically not exchanged, significantly exceed amounts subject to credit or market risk and are not reflected in the Consolidated Balance Sheets. (b)Net derivative assets are included in accrued income and other assets and net derivative liabilities are included in accrued expenses and other liabilities on the Consolidated Balance Sheets. Included in the fair value of net derivative assets and net derivative liabilities are credit valuation adjustments reflecting counterparty credit risk and credit risk of the Corporation. The fair value of net derivative assets included credit valuation adjustments for counterparty credit risk of $25 million and $9 million at June 30, 2020 and December 31, 2019, respectively.
Schedule of the Effects of Fair Value Hedging on the Consolidated Statements of Comprehensive Income	The following table details the effects of fair value hedging on the Consolidated Statements of Comprehensive Income. Interest on Medium- and Long-Term Debt   Three Months Ended June 30, Six Months Ended June 30, (in millions) 2020 2019 2020 2019 Total interest on medium- and long-term debt (a) $ 19    $ 51    $ 59    $ 102    Fair value hedging relationships: Interest rate contracts: Hedged items 28    26    58    52    Derivatives designated as hedging instruments (12)   —    (18)   1    (a) Includes the effects of hedging.
Schedule Of Weighted Average Maturity And Interest Rates On Risk Management Cash Flow Swaps [Text Block]	The following table summarizes the expected weighted average remaining maturity of the notional amount of risk management interest rate swaps, the carrying amount of the related hedged items and the weighted average interest rates associated with amounts expected to be received or paid on interest rate swap agreements as of June 30, 2020 and December 31, 2019. Cash flow swaps - receive fixed/pay floating rate on variable-rate loans: (dollar amounts in millions) June 30, 2020 December 31, 2019 Derivative notional amount $ 5,550    $ 4,550    Weighted average:    Remaining maturity (in years) 2.8    3.0       Receive rate 1.87  % 1.94  %    Pay rate (a) 0.17    1.71    (a)Variable rates paid on receive fixed swaps designated as cash flow hedges are based on one-month LIBOR rates in effect at June 30, 2020 and December 31, 2019.
Schedule Of Weighted Average Maturity And Interest Rates On Risk Management Interest Rate Swaps	Fair value swaps - receive fixed/pay floating rate on medium- and long-term debt: (dollar amounts in millions) June 30, 2020 December 31, 2019 Derivative notional amount $ 2,650    $ 3,325    Carrying value of hedged items (a) 2,971    3,469    Weighted average:    Remaining maturity (in years) 5.1    4.6       Receive rate 3.68  % 3.44  %    Pay rate (b) 1.54    2.80    (a)Included $322 million and $146 million of cumulative hedging adjustments at June 30, 2020 and December 31, 2019, respectively, which included $6 million and $7 million, respectively, of hedging adjustment on a discontinued hedging relationship. (b)Variable rates paid on receive fixed swaps designated as fair value hedges are based on one- and six-month LIBOR rates in effect at June 30, 2020 and December 31, 2019.
Schedule Of Net Gains Recognized In Income On Customer-Initiated Derivatives	The net gains recognized in income on customer-initiated derivative instruments, net of the impact of offsetting positions, were as follows. Three Months Ended June 30, Six Months Ended June 30, (in millions) Location of Gain 2020 2019 2020 2019 Interest rate contracts Other noninterest income $ 8    $ 6    $ 16    $ 12    Energy contracts Other noninterest income 2    2    3    3    Foreign exchange contracts Foreign exchange income 9    11    20    22    Total   $ 19    $ 19    $ 39    $ 37
Schedule Of Financial Instruments With Off-Balance Sheet Credit Risk	The Corporation’s credit risk associated with these instruments is represented by the contractual amounts indicated in the following table. (in millions) June 30, 2020 December 31, 2019 Unused commitments to extend credit: Commercial and other $ 22,588    $ 23,681    Bankcard, revolving check credit and home equity loan commitments 3,275    3,180    Total unused commitments to extend credit $ 25,863    $ 26,861    Standby letters of credit $ 3,185    $ 3,320    Commercial letters of credit 19    18
Summary Of Criticized Letters Of Credit	The following table presents a summary of criticized standby and commercial letters of credit at June 30, 2020 and December 31, 2019. The Corporation's criticized list is generally consistent with the Special Mention, Substandard and Doubtful categories defined by regulatory authorities. The Corporation manages credit risk through underwriting, periodically reviewing and approving its credit exposures using Board committee approved credit policies and guidelines. (dollar amounts in millions) June 30, 2020 December 31, 2019 Total criticized standby and commercial letters of credit $ 83    $ 44    As a percentage of total outstanding standby and commercial letters of credit 2.6  % 1.3  %

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- Definition Schedule of financial instruments, excluding certain derivatives, with off-balance sheet credit risk (for example, unused commitments, standby letters of credit or financial guarantees). + References No definition available. + Details Name: cma_CreditRiskFinancialInstrumentsOffBalanceSheetRiskTableTextBlock Namespace Prefix: cma_ Data Type: nonnum:textBlockItemType Balance Type: na Period Type: duration

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- Definition [Table Text Block] for Effects of fair value hedging of the derivative instruments used for managing interest rate risk on the Consolidated Statements o Comprehensive Income [Table] + References No definition available. + Details Name: cma_EffectsoffairvaluehedgingontheConsolidatedStatementsoComprehensiveIncomeTableTextBlock Namespace Prefix: cma_ Data Type: nonnum:textBlockItemType Balance Type: na Period Type: duration

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- Definition Location and amount of gains (losses) recognized in income related to customer-initiated derivative instruments, net of the impact of offsetting positions. + References No definition available. + Details Name: cma_ScheduleOfCustomerInitiatedDerivativesGainsLossesRecognizedInIncomeLocationTableTextBlock Namespace Prefix: cma_ Data Type: nonnum:textBlockItemType Balance Type: na Period Type: duration

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- Definition Total internally classified watch list standby and commercial letters of credit (generally consistent with regulatory defined special mention, substandard and doubtful). + References No definition available. + Details Name: cma_ScheduleOfInternallyClassifiedWatchListLettersOfCreditTextBlock Namespace Prefix: cma_ Data Type: nonnum:textBlockItemType Balance Type: na Period Type: duration

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- Definition Schedule Of Weighted Average Maturity And Interest Rates On Risk Management Cash Flow Swaps [Text Block] + References No definition available. + Details Name: cma_ScheduleOfWeightedAverageMaturityAndInterestRatesOnRiskManagementCashFlowSwapsTextBlock Namespace Prefix: cma_ Data Type: nonnum:textBlockItemType Balance Type: na Period Type: duration

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- Definition Weighted average remaining maturity of the notional amount of risk management interest rate swaps and weighted average interest rates. + References No definition available. + Details Name: cma_ScheduleOfWeightedAverageMaturityAndInterestRatesOnRiskManagementFairValueSwapsTextBlock Namespace Prefix: cma_ Data Type: nonnum:textBlockItemType Balance Type: na Period Type: duration

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- References No definition available. + Details Name: us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosureAbstract Namespace Prefix: us-gaap_ Data Type: xbrli:stringItemType Balance Type: na Period Type: duration

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- Definition Tabular disclosure of the location and fair value amounts of derivative instruments (and nonderivative instruments that are designated and qualify as hedging instruments) reported in the statement of financial position. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4B -URI http://asc.fasb.org/extlink&oid=121590274&loc=SL5624163-113959 + Details Name: us-gaap_ScheduleOfDerivativeInstrumentsInStatementOfFinancialPositionFairValueTextBlock Namespace Prefix: us-gaap_ Data Type: nonnum:textBlockItemType Balance Type: na Period Type: duration

v3.20.2

Variable Interest Entities (VIEs) (Tables)	6 Months Ended
	Jun. 30, 2020
Variable Interest Entity, Not Primary Beneficiary, Disclosures [Abstract]
Impact Of VIEs On The Consolidated Statements Of Comprehensive Income	The following table summarizes the impact of these tax credit entities on the Corporation’s Consolidated Statements of Comprehensive Income. Three Months Ended June 30, Six Months Ended June 30, (in millions) 2020 2019 2020 2019 Other noninterest income: Amortization of other tax credit investments $ —    $ —    $ —    $ 1    Provision for income taxes: Amortization of LIHTC investments 17    17    34    32    Low income housing tax credits (16)   (15)   (32)   (30)   Other tax benefits related to tax credit entities (3)   (4)   (7)   (7)   Total provision for income taxes $ (2)   $ (2)   $ (5)   $ (5)

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- Definition Tabular disclosure of the significant judgments and assumptions made in determining whether a variable interest (as defined) held by the entity requires the variable interest entity (VIE) (as defined) to be consolidated and (or) disclose information about its involvement with the VIE, individually or in aggregate (as applicable); the nature of restrictions, if any, on the consolidated VIE's assets and on the settlement of its liabilities reported by an entity in its statement of financial position, including the carrying amounts of such assets and liabilities; the nature of, and changes in, the risks associated with involvement in the VIE; how involvement with the VIE affects the entity's financial position, financial performance, and cash flows; the lack of recourse if creditors (or beneficial interest holders) of the consolidated VIE have no recourse to the general credit of the primary beneficiary (if applicable); the terms of arrangements, giving consideration to both explicit arrangements and implicit variable interests, if any, that could require the entity to provide financial support to the VIE, including events or circumstances that could expose the entity to a loss; the methodology used by the entity for determining whether or not it is the primary beneficiary of the variable interest entity; the significant factors considered and judgments made in determining that the power to direct the activities of a VIE that most significantly impact the VIE's economic performance are shared (as defined); the carrying amounts and classification of assets and liabilities of the VIE included in the statement of financial position; the entity's maximum exposure to loss, if any, as a result of its involvement with the VIE, including how the maximum exposure is determined and significant sources of the entity's exposure to the VIE; a comparison of the carrying amounts of the assets and liabilities and the entity's maximum exposure to loss; information about any liquidity arrangements, guarantees, and (or) other commitments by third parties that may affect the fair value or risk of the entity's variable interest in the VIE; whether or not the entity has provided financial support or other support (explicitly or implicitly) to the VIE that it was not previously contractually required to provide or whether the entity intends to provide that support, including the type and amount of the support and the primary reasons for providing the support; and supplemental information the entity determines necessary to provide. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 810 -SubTopic 10 -Section 50 -Paragraph 5A -URI http://asc.fasb.org/extlink&oid=121559654&loc=SL6759159-111685 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 810 -SubTopic 10 -Section 50 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=121559654&loc=d3e5747-111685 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 810 -SubTopic 10 -Section 50 -Paragraph 9 -URI http://asc.fasb.org/extlink&oid=121559654&loc=SL6228884-111685 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 810 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=121559654&loc=d3e5710-111685 Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 810 -SubTopic 10 -Section 50 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=121559654&loc=d3e5728-111685 + Details Name: us-gaap_ScheduleOfVariableInterestEntitiesTextBlock Namespace Prefix: us-gaap_ Data Type: nonnum:textBlockItemType Balance Type: na Period Type: duration

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- References No definition available. + Details Name: us-gaap_VariableInterestEntityNotPrimaryBeneficiaryDisclosuresAbstract Namespace Prefix: us-gaap_ Data Type: xbrli:stringItemType Balance Type: na Period Type: duration

v3.20.2

Medium- And Long-Term Debt (Tables)	6 Months Ended
	Jun. 30, 2020
Debt Disclosure [Abstract]
Schedule Of Medium- And Long-Term Debt	Medium- and long-term debt is summarized as follows: (in millions) June 30, 2020 December 31, 2019 Parent company Subordinated notes: 3.80% subordinated notes due 2026 (a) $ 284    $ 264    Medium- and long-term notes: 3.70% notes due 2023 (a) 917    884    4.00% notes due 2029 (a) 647    587    Total medium- and long-term notes 1,564    1,471    Total parent company 1,848    1,735    Subsidiaries Subordinated notes: 4.00% subordinated notes due 2025 (a) 383    360    7.875% subordinated notes due 2026 (a) 213    202    Total subordinated notes 596    562    Medium- and long-term notes: 2.50% notes due 2020 (a) —    674    2.50% notes due 2024 (a) 527    498    Total medium- and long-term notes 527    1,172    FHLB advances: Floating-rate based on FHLB auction rate due 2026 2,800    2,800    Floating-rate based on FHLB auction rate due 2028 750    1,000    Total FHLB advances 3,550    3,800    Total subsidiaries 4,673    5,534    Total medium- and long-term debt $ 6,521    $ 7,269    (a)The fixed interest rates on these notes have been swapped to a variable rate and designated in a hedging relationship. Accordingly, carrying value has been adjusted to reflect the change in the fair value of the debt as a result of changes in the benchmark rate.

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- Definition Tabular disclosure of long-debt instruments or arrangements, including identification, terms, features, collateral requirements and other information necessary to a fair presentation. These are debt arrangements that originally required repayment more than twelve months after issuance or greater than the normal operating cycle of the entity, if longer. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 45 -Paragraph 1A -URI http://asc.fasb.org/extlink&oid=119993939&loc=d3e28541-108399 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21506-112644 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.4-08.(e),(f)) -URI http://asc.fasb.org/extlink&oid=120395691&loc=d3e23780-122690 Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=119993939&loc=d3e28551-108399 Reference 6: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21521-112644 Reference 7: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21538-112644 Reference 8: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 470 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=75038535&loc=d3e64711-112823 Reference 9: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 55 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400 Reference 10: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21475-112644 + Details Name: us-gaap_ScheduleOfDebtInstrumentsTextBlock Namespace Prefix: us-gaap_ Data Type: nonnum:textBlockItemType Balance Type: na Period Type: duration

v3.20.2

Accumulated Other Comprehensive Income (Loss) (Tables)	6 Months Ended
	Jun. 30, 2020
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Schedule Of Accumulated Other Comprehensive Loss	The following table presents a reconciliation of the changes in the components of accumulated other comprehensive income (loss) and details the components of other comprehensive income (loss) for the six months ended June 30, 2020 and 2019, including the amount of income tax expense (benefit) allocated to each component of other comprehensive income (loss). Six Months Ended June 30, (in millions) 2020 2019 Accumulated net unrealized gains on investment securities: Balance at beginning of period, net of tax $ 65    $ (138)   Net unrealized holding gains arising during the period 286    229    Less: Provision for income taxes 68    54    Net unrealized holding gains arising during the period, net of tax 218    175    Less: Net realized losses included in net securities losses —    (8)   Less: Benefit for income taxes —    (2)   Reclassification adjustment for net securities losses included in net income, net of tax —    (6)   Change in net unrealized gains on investment securities, net of tax 218    181    Balance at end of period, net of tax $ 283    $ 43    Accumulated net gains on cash flow hedges: Balance at beginning of period, net of tax $ 34    $ —    Net cash flow hedge gains arising during the period 233    51    Less: Provision for income taxes 56    12    Change in net cash flow hedge gains arising during the period, net of tax 177    39    Less: Net cash flow hedge gains (losses) included in interest and fees on loans 22    (1)   Less: Provision for income taxes 7    —    Reclassification adjustment for net cash flow hedge gains (losses) included in net income, net of tax 15    (1)   Change in net cash flow hedge gains, net of tax 162    40    Balance at end of period, net of tax (a) $ 196    $ 40    Accumulated defined benefit pension and other postretirement plans adjustment: Balance at beginning of period, net of tax $ (334)   $ (471)   Amortization of actuarial net loss 31    21    Amortization of prior service credit (14)   (13)   Amounts recognized in other noninterest expenses 17    8    Less: Provision for income taxes 4    2    Change in defined benefit pension and other postretirement plans adjustment, net of tax 13    6    Balance at end of period, net of tax $ (321)   $ (465)   Total accumulated other comprehensive income (loss) at end of period, net of tax $ 158    $ (382)   (a)The Corporation expects to reclassify $73 million of net gains, net of tax, from accumulated other comprehensive income to earnings over the next twelve months if interest yield curves and notional amounts remain at June 30, 2020 levels.

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- Definition Tabular disclosure of the components of accumulated other comprehensive income (loss). + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 830 -SubTopic 30 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6450520&loc=d3e32583-110901 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 14A -URI http://asc.fasb.org/extlink&oid=121641772&loc=SL7669686-108580 Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 830 -SubTopic 30 -Section 45 -Paragraph 20 -URI http://asc.fasb.org/extlink&oid=118261656&loc=d3e32211-110900 + Details Name: us-gaap_ScheduleOfAccumulatedOtherComprehensiveIncomeLossTableTextBlock Namespace Prefix: us-gaap_ Data Type: nonnum:textBlockItemType Balance Type: na Period Type: duration

v3.20.2

Net Income Per Common Share (Tables)	6 Months Ended
	Jun. 30, 2020
Earnings Per Share [Abstract]
Basic And Diluted Net Income Per Common Share	NET INCOME PER COMMON SHARE Basic and diluted net income per common share are presented in the following table. Three Months Ended June 30, Six Months Ended June 30, (in millions, except per share data) 2020 2019 2020 2019 Basic and diluted Net income $ 113    $ 298    $ 48    $ 637    Less: Income allocated to participating securities 1    1    1    3    Net income attributable to common share $ 112    $ 297    $ 47    $ 634    Basic average common shares 139    152    140    155    Basic net income per common share $ 0.81    $ 1.95    $ 0.34    $ 4.10    Basic average common shares 139    152    140    155    Dilutive common stock equivalents: Net effect of the assumed exercise of stock awards —    1    1    1    Diluted average common shares 139    153    141    156    Diluted net income per common share $ 0.80    $ 1.94    $ 0.34    $ 4.06
Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share	Three Months Ended June 30, Six Months Ended June 30, 2020 2019 2020 2019 Average outstanding options 2,056,133    470,162    1,633,078    446,610    Range of exercise prices $39.10 - $95.25 $79.01 - $95.25 $39.10 - $95.25 $79.01 - $95.25

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- Definition Tabular disclosure of securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) in the future that were not included in the computation of diluted EPS because to do so would increase EPS amounts or decrease loss per share amounts for the period presented, by antidilutive securities. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 260 -SubTopic 10 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257 + Details Name: us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTextBlock Namespace Prefix: us-gaap_ Data Type: nonnum:textBlockItemType Balance Type: na Period Type: duration

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- Definition Tabular disclosure of an entity's basic and diluted earnings per share calculations, including a reconciliation of numerators and denominators of the basic and diluted per-share computations for income from continuing operations. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 260 -SubTopic 10 -Section 50 -Paragraph 1 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257 + Details Name: us-gaap_ScheduleOfEarningsPerShareBasicAndDilutedTableTextBlock Namespace Prefix: us-gaap_ Data Type: nonnum:textBlockItemType Balance Type: na Period Type: duration

v3.20.2

Employee Benefit Plans (Tables)	6 Months Ended
	Jun. 30, 2020
Retirement Benefits [Abstract]
Components of Net Periodic Benefit Cost	The components of net periodic benefit cost (credit) for the Corporation's qualified pension plan, non-qualified pension plan and postretirement benefit plan are as follows. Qualified Defined Benefit Pension Plan Three Months Ended June 30, Six Months Ended June 30, (in millions) 2020 2019 2020 2019 Service cost $ 8    $ 7    $ 16    $ 15    Other components of net benefit credit: Interest cost 17    20    35    40    Expected return on plan assets (42)   (41)   (85)   (83)   Amortization of prior service credit (5)   (4)   (10)   (9)   Amortization of net loss 13    8    27    17    Total other components of net benefit credit (17)   (17)   (33)   (35)   Net periodic defined benefit credit $ (9)   $ (10)   $ (17)   $ (20)   Non-Qualified Defined Benefit Pension Plan Three Months Ended June 30, Six Months Ended June 30, (in millions) 2020 2019 2020 2019 Service cost $ —    $ 1    $ 1    $ 2    Other components of net benefit cost: Interest cost 2    2    4    4    Amortization of prior service credit (2)   (2)   (4)   (4)   Amortization of net loss 2    2    4    4    Total other components of net benefit cost 2    2    4    4    Net periodic defined benefit cost $ 2    $ 3    $ 5    $ 6    Postretirement Benefit Plan Three Months Ended June 30, Six Months Ended June 30, (in millions) 2020 2019 2020 2019 Other components of net benefit credit: Interest cost $ —    $ —    $ —    $ 1    Expected return on plan assets (1)   —    (1)   (1)   Net periodic defined benefit credit $ (1)   $ —    $ (1)   $ —

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- References No definition available. + Details Name: us-gaap_CompensationAndRetirementDisclosureAbstract Namespace Prefix: us-gaap_ Data Type: xbrli:stringItemType Balance Type: na Period Type: duration

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- Definition Tabular disclosure of the components of net benefit costs for pension plans and/or other employee benefit plans including service cost, interest cost, expected return on plan assets, gain (loss), prior service cost or credit, transition asset or obligation, and gain (loss) recognized due to settlements or curtailments. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (h) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 + Details Name: us-gaap_ScheduleOfNetBenefitCostsTableTextBlock Namespace Prefix: us-gaap_ Data Type: nonnum:textBlockItemType Balance Type: na Period Type: duration

v3.20.2

Business Segment Information (Tables)	6 Months Ended
	Jun. 30, 2020
Segment Reporting [Abstract]
Business Segment Financial Results	Business segment financial results are as follows: Commercial Bank Retail Bank Wealth Management Finance Other Total (dollar amounts in millions) Three Months Ended June 30, 2020 Earnings summary: Net interest income (expense) $ 402    $ 120    $ 40    $ (95)   $ 4    $ 471    Provision for credit losses 117    5    16    —    —    138    Noninterest income 144    24    66    11    2    247    Noninterest expenses 207    155    73    1    4    440    Provision (benefit) for income taxes 47    (4)   3    (20)   1    27    Net income (loss) $ 175    $ (12)   $ 14    $ (65)   $ 1    $ 113    Net credit-related charge-offs $ 48    $ 1    $ 1    $ —    $ —    $ 50    Selected average balances: Assets $ 47,392    $ 3,306    $ 5,191    $ 14,500    $ 11,255    $ 81,644    Loans 45,914    2,479    5,077    —    28    53,498    Deposits 36,318    22,647    4,217    950    150    64,282    Statistical data: Return on average assets (a) 1.49  % (0.21) % 1.00  % n/m n/m 0.55  % Efficiency ratio (b) 37.67    107.15    69.86    n/m n/m 61.14    Three Months Ended June 30, 2019 Earnings summary: Net interest income (expense) $ 420    $ 146    $ 46    $ (23)   $ 14    $ 603    Provision for credit losses 52    1    (5)   —    (4)   44    Noninterest income 136    33    68    13    —    250    Noninterest expenses 195    147    67    —    15    424    Provision (benefit) for income taxes 71    7    13    (4)   —    87    Net income (loss) $ 238    $ 24    $ 39    $ (6)   $ 3    $ 298    Net credit-related charge-offs (recoveries) $ 35    $ —    $ (2)   $ —    $ —    $ 33    Selected average balances: Assets $ 45,321    $ 2,839    $ 5,071    $ 13,907    $ 4,114    $ 71,252    Loans 43,932    2,107    4,930    —    (6)   50,963    Deposits 28,251    20,649    3,740    2,174    181    54,995    Statistical data: Return on average assets (a) 2.11  % 0.44  % 3.10  % n/m n/m 1.68  % Efficiency ratio (b) 34.98    82.26    58.99    n/m n/m 49.65    (a)Return on average assets is calculated based on the greater of average assets or average liabilities and attributed equity. (b)Noninterest expenses as a percentage of the sum of net interest income and noninterest income excluding net gains (losses) from securities and a derivative contract tied to the conversion rate of Visa Class B shares. n/m – not meaningful Commercial Bank Retail Bank Wealth Management Finance Other Total (dollar amounts in millions) Six Months Ended June 30, 2020 Earnings summary: Net interest income (expense) $ 782    $ 245    $ 81    $ (139)   $ 15    $ 984    Provision for credit losses 513    8    28    —    —    549    Noninterest income 271    52    136    25    —    484    Noninterest expenses 401    304    145    1    14    865    Provision (benefit) for income taxes 27    (4)   9    (28)   2    6    Net income (loss) $ 112    $ (11)   $ 35    $ (87)   $ (1)   $ 48    Net credit-related charge-offs $ 131    $ 2    $ 1    $ —    $ —    $ 134    Selected average balances: Assets $ 45,823    $ 3,085    $ 5,134    $ 14,393    $ 9,019    $ 77,454    Loans 44,253    2,277    5,007    —    14    51,551    Deposits 33,274    21,921    4,120    1,043    166    60,524    Statistical data: Return on average assets (a) 0.49  % (0.10) % 1.34  % n/m n/m 0.12  % Efficiency ratio (b) 38.05    101.41    67.00    n/m n/m 58.80    Six Months Ended June 30, 2019 Earnings summary: Net interest income (expense) $ 832    $ 292    $ 93    $ (37)   $ 29    $ 1,209    Provision for credit losses 46    (3)   (10)   —    (2)   31    Noninterest income 272    64    132    17    3    488    Noninterest expenses 393    292    139    1    32    857    Provision (benefit) for income taxes 153    16    23    (8)   (12)   172    Net income (loss) $ 512    $ 51    $ 73    $ (13)   $ 14    $ 637    Net credit-related charge-offs (recoveries) $ 47    $ —    $ (3)   $ —    $ —    $ 44    Selected average balances: Assets $ 44,619    $ 2,826    $ 5,121    $ 13,747    $ 4,202    $ 70,515    Loans 43,241    2,105    4,983    —    (6)   50,323    Deposits 28,356    20,560    3,770    1,655    157    54,498    Statistical data: Return on average assets (a) 2.31  % 0.49  % 2.88  % n/m n/m 1.82  % Efficiency ratio (b) 35.61    81.80    61.67    n/m n/m 50.23    (a)Return on average assets is calculated based on the greater of average assets or average liabilities and attributed equity. (b)Noninterest expenses as a percentage of the sum of net interest income and noninterest income excluding net gains (losses) from securities and a derivative contract tied to the conversion rate of Visa Class B shares. n/m – not meaningful
Market Segment Financial Results	Market segment financial results are as follows: Michigan California Texas Other Markets Finance & Other Total (dollar amounts in millions) Three Months Ended June 30, 2020 Earnings summary: Net interest income (expense) $ 159    $ 176    $ 116    $ 111    $ (91)   $ 471    Provision for credit losses 40    51    31    16    —    138    Noninterest income 64    36    30    104    13    247    Noninterest expenses 139    103    91    102    5    440    Provision (benefit) for income taxes 8    13    4    21    (19)   27    Net income (loss) $ 36    $ 45    $ 20    $ 76    $ (64)   $ 113    Net credit-related charge-offs $ —    $ 4    $ 46    $ —    $ —    $ 50    Selected average balances: Assets $ 13,643    $ 18,948    $ 11,597    $ 11,732    $ 25,724    $ 81,644    Loans 13,014    18,663    11,184    10,640    (3)   53,498    Deposits 23,460    18,463    10,209    11,050    1,100    64,282    Statistical data: Return on average assets (a) 0.59  % 0.93  % 0.68  % 2.53  % n/m 0.55  % Efficiency ratio (b) 62.08    48.61    61.88    47.41    n/m 61.14    Three Months Ended June 30, 2019 Earnings summary: Net interest income (expense) $ 186    $ 208    $ 124    $ 94    $ (9)   $ 603    Provision for credit losses (10)   (4)   49    13    (4)   44    Noninterest income 72    40    34    91    13    250    Noninterest expenses 134    99    84    92    15    424    Provision (benefit) for income taxes 30    39    6    16    (4)   87    Net income (loss) $ 104    $ 114    $ 19    $ 64    $ (3)   $ 298    Net credit-related charge-offs $ —    $ 7    $ 26    $ —    $ —    $ 33    Selected average balances: Assets $ 13,239    $ 19,108    $ 11,342    $ 9,542    $ 18,021    $ 71,252    Loans 12,704    18,806    10,684    8,775    (6)   50,963    Deposits 19,816    16,314    8,668    7,842    2,355    54,995    Statistical data: Return on average assets (a) 2.01  % 2.38  % 0.69  % 2.75  % n/m 1.68  % Efficiency ratio (b) 52.04    40.07    52.86    49.36    n/m 49.65    (a)Return on average assets is calculated based on the greater of average assets or average liabilities and attributed equity. (b)Noninterest expenses as a percentage of the sum of net interest income and noninterest income excluding net gains (losses) from securities and a derivative contract tied to the conversion rate of Visa Class B shares. n/m – not meaningful. Michigan California Texas Other Markets Finance & Other Total (dollar amounts in millions) Six Months Ended June 30, 2020 Earnings summary: Net interest income (expense) $ 322    $ 358    $ 231    $ 197    $ (124)   $ 984    Provision for credit losses 64    102    321    62    —    549    Noninterest income 136    72    60    191    25    484    Noninterest expenses 279    201    175    195    15    865    Provision (benefit) for income taxes 23    30    (46)   25    (26)   6    Net income (loss) $ 92    $ 97    $ (159)   $ 106    $ (88)   $ 48    Net credit-related charge-offs $ 3    $ 15    $ 116    $ —    $ —    $ 134    Selected average balances: Assets $ 13,269    $ 18,664    $ 11,371    $ 10,754    $ 23,396    $ 77,454    Loans 12,601    18,346    10,870    9,735    (1)   51,551    Deposits 22,104    17,965    9,705    9,541    1,209    60,524    Statistical data: Return on average assets (a) 0.81  % 1.02  % (2.82) % 1.99  % n/m 0.12  % Efficiency ratio (b) 60.46    46.77    60.07    50.25    n/m 58.80    Six Months Ended June 30, 2019 Earnings summary: Net interest income (expense) $ 373    $ 411    $ 248    $ 185    $ (8)   $ 1,209    Provision for credit losses (5)   (5)   38    5    (2)   31    Noninterest income 144    80    66    178    20    488    Noninterest expenses 273    199    169    183    33    857    Provision (benefit) for income taxes 56    76    25    35    (20)   172    Net income $ 193    $ 221    $ 82    $ 140    $ 1    $ 637    Net credit-related charge-offs (recoveries) $ 4    $ 4    $ 39    $ (3)   $ —    $ 44    Selected average balances: Assets $ 13,157    $ 19,020    $ 11,128    $ 9,261    $ 17,949    $ 70,515    Loans 12,631    18,730    10,474    8,494    (6)   50,323    Deposits 19,854    16,276    8,682    7,874    1,812    54,498    Statistical data: Return on average assets (a) 1.89  % 2.35  % 1.47  % 3.06  % n/m 1.82  % Efficiency ratio (b) 52.85    40.49    53.74    50.30    n/m 50.23    (a)Return on average assets is calculated based on the greater of average assets or average liabilities and attributed equity. (b)Noninterest expenses as a percentage of the sum of net interest income and noninterest income excluding net gains (losses) from securities and a derivative contract tied to the conversion rate of Visa Class B shares. n/m – not meaningful.

X

- Definition Market Segment Financial Results + References No definition available. + Details Name: cma_MarketSegmentFinancialResultsTableTextBlock Namespace Prefix: cma_ Data Type: nonnum:textBlockItemType Balance Type: na Period Type: duration

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- Definition Tabular disclosure of the profit or loss and total assets for each reportable segment. An entity discloses certain information on each reportable segment if the amounts (a) are included in the measure of segment profit or loss reviewed by the chief operating decision maker or (b) are otherwise regularly provided to the chief operating decision maker, even if not included in that measure of segment profit or loss. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 280 -SubTopic 10 -Section 50 -Paragraph 22 -URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8736-108599 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 280 -SubTopic 10 -Section 50 -Paragraph 25 -URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8813-108599 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 20 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=121556970&loc=d3e13816-109267 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 280 -SubTopic 10 -Section 50 -Paragraph 30 -URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8906-108599 + Details Name: us-gaap_ScheduleOfSegmentReportingInformationBySegmentTextBlock Namespace Prefix: us-gaap_ Data Type: nonnum:textBlockItemType Balance Type: na Period Type: duration

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- References No definition available. + Details Name: us-gaap_SegmentReportingAbstract Namespace Prefix: us-gaap_ Data Type: xbrli:stringItemType Balance Type: na Period Type: duration

v3.20.2

Revenue from Contracts with Customers (Tables)	6 Months Ended
	Jun. 30, 2020
Revenue from Contract with Customer [Abstract]
Composition of Revenue from Contracts with Customers	The following table presents the composition of revenue from contracts with customers, segregated from other sources of noninterest income, by business segment. Commercial Bank Retail Bank Wealth Management Finance & Other Total (in millions) Three Months Ended June 30, 2020 Revenue from contracts with customers: Card fees $ 59    $ 8    $ 1    $ —    $ 68    Service charges on deposit accounts 30    11    1    —    42    Fiduciary income —    —    52    —    52    Commercial loan servicing fees (a) 4    —    —    —    4    Brokerage fees —    —    5    —    5    Other noninterest income (b) 11    2    4    —    17    Total revenue from contracts with customers 104    21    63    —    188    Other sources of noninterest income 40    3    3    13    59    Total noninterest income $ 144    $ 24    $ 66    $ 13    $ 247    Three Months Ended June 30, 2019 Revenue from contracts with customers: Card fees $ 54    $ 10    $ 1    $ —    $ 65    Service charges on deposit accounts 33    17    1    —    51    Fiduciary income —    —    52    —    52    Commercial loan servicing fees (a) 4    —    —    —    4    Brokerage fees —    —    7    —    7    Other noninterest income (b) 2    4    4    —    10    Total revenue from contracts with customers 93    31    65    —    189    Other sources of noninterest income 43    2    3    13    61    Total noninterest income $ 136    $ 33    $ 68    $ 13    $ 250    Six Months Ended June 30, 2020 Revenue from contracts with customers: Card fees $ 108    $ 17    $ 2    $ —    $ 127    Service charges on deposit accounts 62    27    2    —    91    Fiduciary income —    —    106    —    106    Commercial loan servicing fees (a) 8    —    —    —    8    Brokerage fees —    —    12    —    12    Other noninterest income (b) 15    5    9    —    29    Total revenue from contracts with customers 193    49    131    —    373    Other sources of noninterest income 78    3    5    25    111    Total noninterest income $ 271    $ 52    $ 136    $ 25    $ 484    Six Months Ended June 30, 2019 Revenue from contracts with customers: Card fees $ 107    $ 19    $ 2    $ —    $ 128    Service charges on deposit accounts 66    34    2    —    102    Fiduciary income —    —    101    —    101    Commercial loan servicing fees (a) 8    —    —    —    8    Brokerage fees —    —    14    —    14    Other noninterest income (b) 4    7    9    —    20    Total revenue from contracts with customers 185    60    128    —    373    Other sources of noninterest income 87    4    4    20    115    Total noninterest income $ 272    $ 64    $ 132    $ 20    $ 488    (a)Included in commercial lending fees on the Consolidated Statements of Comprehensive Income. (b)Excludes derivative, warrant and other miscellaneous income.

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- Definition Tabular disclosure of disaggregation of revenue into categories depicting how nature, amount, timing, and uncertainty of revenue and cash flows are affected by economic factor. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 606 -SubTopic 10 -Section 50 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130545-203045 + Details Name: us-gaap_DisaggregationOfRevenueTableTextBlock Namespace Prefix: us-gaap_ Data Type: nonnum:textBlockItemType Balance Type: na Period Type: duration

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- References No definition available. + Details Name: us-gaap_RevenueFromContractWithCustomerAbstract Namespace Prefix: us-gaap_ Data Type: xbrli:stringItemType Balance Type: na Period Type: duration

v3.20.2

Basis of Presentation and Accounting Policies Basis of Presentation and Accounting Policies (Narrative) (Details) - USD ($) $ in Millions			3 Months Ended	6 Months Ended
	Jan. 01, 2020	Jan. 01, 2019	Jun. 30, 2020	Jun. 30, 2020	Dec. 31, 2019
Increase in the CET1 capital ratio					0.02%
Increase in retail loans allowance for credit losses	$ 25
LIBOR loans percent of portfolio			72.00%	72.00%
Overall allowance for credit losses					$ 668
Cumulative effect of change in accounting principle	13	$ (14)
Business loans percent of portfolio					91.00%
Percent of loan portfolio with interest rate swaps to convert variable-LBIOR to fixed rates			11.00%	11.00%
Accounting Standards Update 2018-15 [Member]
Hosting fees previously including in outside processing fee expense			$ 8	$ 15
Accounting Standards Update 2016-13 [Member]
Day-one decrease in the overall allowance for credit losses	(17)	0
Reduction in business loans allowance for credit losses	(42)	0
Increase in retail loans allowance for credit losses	25	0
Reduction to deferred tax asset	4
Retained Earnings
Cumulative effect of change in accounting principle	13	$ (14)
Retained Earnings | Accounting Standards Update 2016-13 [Member]
Cumulative effect of change in accounting principle	$ 13

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- Definition Business loans percent of portfolio + References No definition available. + Details Name: cma_Businessloanspercentofportfolio Namespace Prefix: cma_ Data Type: num:percentItemType Balance Type: na Period Type: instant

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- Definition Cumulative effect of change in accounting principle + References No definition available. + Details Name: cma_CumulativeEffectOfChangeInAccountingPrinciple Namespace Prefix: cma_ Data Type: xbrli:monetaryItemType Balance Type: credit Period Type: duration

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- Definition Day-one decrease in the overall allowance for credit losses + References No definition available. + Details Name: cma_Dayonedecreaseintheoverallallowanceforcreditlosses Namespace Prefix: cma_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: instant

X

- Definition Hosting fees previously including in outside processing fee expense + References No definition available. + Details Name: cma_Hostingfeespreviouslyincludinginoutsideprocessingfeeexpense Namespace Prefix: cma_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: duration

X

- Definition Increase in retail loans allowance for credit losses + References No definition available. + Details Name: cma_Increaseinretailloansallowanceforcreditlosses Namespace Prefix: cma_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: instant

X

- Definition Increase in the CET1 capital ratio + References No definition available. + Details Name: cma_IncreaseintheCET1capitalratio Namespace Prefix: cma_ Data Type: num:percentItemType Balance Type: na Period Type: instant

X

- Definition LIBOR loans percent of portfolio + References No definition available. + Details Name: cma_LIBORloanspercentofportfolio Namespace Prefix: cma_ Data Type: num:percentItemType Balance Type: na Period Type: instant

X

- Definition Overall allowance for credit losses + References No definition available. + Details Name: cma_Overallallowanceforcreditlosses Namespace Prefix: cma_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: instant

X

- Definition Percent of loan portfolio with interest rate swaps to convert variable-LBIOR to fixed rates + References No definition available. + Details Name: cma_PercentofloanportfoliowithinterestrateswapstoconvertvariableLBIORtofixedrates Namespace Prefix: cma_ Data Type: num:percentItemType Balance Type: na Period Type: instant

X

- Definition Reduction in business loans allowance for credit losses + References No definition available. + Details Name: cma_Reductioninbusinessloansallowanceforcreditlosses Namespace Prefix: cma_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: instant

X

- Definition Reduction to deferred tax asset + References No definition available. + Details Name: cma_Reductiontodeferredtaxasset Namespace Prefix: cma_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: instant

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- Details Name: us-gaap_ProspectiveAdoptionOfNewAccountingPronouncementsAxis=us-gaap_AccountingStandardsUpdate201815Member Namespace Prefix: Data Type: na Balance Type: Period Type:

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- Details Name: us-gaap_StatementEquityComponentsAxis=us-gaap_RetainedEarningsMember Namespace Prefix: Data Type: na Balance Type: Period Type:

v3.20.2

Fair Value Measurements (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Recurring
Transfers into or out of Level 3	$ 0	$ 0	$ 0	$ 0
Total liabilities at fair value	443		443		$ 236
Nonrecurring
Total liabilities at fair value	$ 0		$ 0		$ 0

X

- Definition Transfers between Level 1, Level 2 and Level three of the fair value hierarchy that have taken place during the period. + References No definition available. + Details Name: cma_TransfersIntoOrOutOfLevelOneOrLevelTwoOrLevelThree Namespace Prefix: cma_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: duration

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- Definition Fair value of financial and nonfinancial obligations. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258 + Details Name: us-gaap_LiabilitiesFairValueDisclosure Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: credit Period Type: instant

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- Details Name: us-gaap_FairValueByMeasurementFrequencyAxis=us-gaap_FairValueMeasurementsRecurringMember Namespace Prefix: Data Type: na Balance Type: Period Type:

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- Details Name: us-gaap_FairValueByMeasurementFrequencyAxis=us-gaap_FairValueMeasurementsNonrecurringMember Namespace Prefix: Data Type: na Balance Type: Period Type:

v3.20.2

Fair Value Measurements (Assets And Liabilities Recorded At Fair Value On A Recurring Basis) (Details) - USD ($) $ in Millions		Jun. 30, 2020	Dec. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available-for-sale		$ 12,759	$ 12,398
Derivative assets		935	317
Derivative liabilities		351	141
U.S. Treasury and other U.S. government agency securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available-for-sale		2,852	2,792
Residential mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available-for-sale	[1]	9,907	9,606
Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available-for-sale		12,759	12,398
Derivative assets		935	317
Total assets at fair value		13,836	12,864
Derivative liabilities		351	141
Deferred compensation plan liabilities		92	95
Total liabilities at fair value		443	236
Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available-for-sale		2,852	2,792
Derivative assets		0	0
Total assets at fair value		2,994	2,941
Derivative liabilities		0	0
Deferred compensation plan liabilities		92	95
Total liabilities at fair value		92	95
Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available-for-sale		9,907	9,606
Derivative assets		891	295
Total assets at fair value		10,798	9,901
Derivative liabilities		351	141
Deferred compensation plan liabilities		0	0
Total liabilities at fair value		351	141
Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available-for-sale		0	0
Derivative assets		44	22
Total assets at fair value		44	22
Derivative liabilities		0	0
Deferred compensation plan liabilities		0	0
Total liabilities at fair value		0	0
Recurring | Interest rate contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		649	211
Derivative liabilities		73	39
Recurring | Interest rate contracts | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		0	0
Derivative liabilities		0	0
Recurring | Interest rate contracts | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		605	189
Derivative liabilities		73	39
Recurring | Interest rate contracts | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		44	22
Derivative liabilities		0	0
Recurring | Energy derivative contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		271	96
Derivative liabilities		263	92
Recurring | Energy derivative contracts | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		0	0
Derivative liabilities		0	0
Recurring | Energy derivative contracts | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		271	96
Derivative liabilities		263	92
Recurring | Energy derivative contracts | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		0	0
Derivative liabilities		0	0
Recurring | Foreign exchange contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		15	10
Derivative liabilities		15	10
Recurring | Foreign exchange contracts | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		0	0
Derivative liabilities		0	0
Recurring | Foreign exchange contracts | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		15	10
Derivative liabilities		15	10
Recurring | Foreign exchange contracts | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		0	0
Derivative liabilities		0	0
Recurring | Deferred compensation plan assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading securities		92	95
Recurring | Deferred compensation plan assets | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading securities		92	95
Recurring | Deferred compensation plan assets | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading securities		0	0
Recurring | Deferred compensation plan assets | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading securities		0	0
Recurring | Equity and other non-debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other equity securities		50	54
Recurring | Equity and other non-debt securities | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other equity securities		50	54
Recurring | Equity and other non-debt securities | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other equity securities		0	0
Recurring | Equity and other non-debt securities | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other equity securities		0	0
Recurring | U.S. Treasury and other U.S. government agency securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available-for-sale		2,852	2,792
Recurring | U.S. Treasury and other U.S. government agency securities | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available-for-sale		2,852	2,792
Recurring | U.S. Treasury and other U.S. government agency securities | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available-for-sale		0	0
Recurring | U.S. Treasury and other U.S. government agency securities | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available-for-sale		0	0
Recurring | Residential mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available-for-sale	[1]	9,907	9,606
Recurring | Residential mortgage-backed securities | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available-for-sale	[1]	0	0
Recurring | Residential mortgage-backed securities | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available-for-sale	[1]	9,907	9,606
Recurring | Residential mortgage-backed securities | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available-for-sale	[1]	$ 0	$ 0
[1] Issued and/or guaranteed by U.S. government agencies or U.S. government-sponsored enterprises.

X

- Definition Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258 + Details Name: us-gaap_AssetsFairValueDisclosure Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: instant

X

- Definition Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading. + References No definition available. + Details Name: us-gaap_AvailableForSaleSecurities Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: instant

X

- Definition Aggregate carrying value as of the balance sheet date of the liabilities for all deferred compensation arrangements. Represents currently earned compensation under compensation arrangements that is not actually paid until a later date. + References No definition available. + Details Name: us-gaap_DeferredCompensationLiabilityCurrentAndNoncurrent Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: credit Period Type: instant

X

- Definition Fair value, before effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets elected not to be offset. Excludes assets not subject to a master netting arrangement. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 55 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=99393222&loc=SL20226000-175313 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 860 -SubTopic 20 -Section 50 -Paragraph 4D -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=121570589&loc=SL51823488-111719 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 50 -Paragraph 3 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4B -Subparagraph (a),(c) -URI http://asc.fasb.org/extlink&oid=121590274&loc=SL5624163-113959 + Details Name: us-gaap_DerivativeFairValueOfDerivativeAsset Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: instant

X

- Definition Fair value, before effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities elected not to be offset. Excludes liabilities not subject to a master netting arrangement. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 860 -SubTopic 20 -Section 50 -Paragraph 4D -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=121570589&loc=SL51823488-111719 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4B -Subparagraph (a),(c) -URI http://asc.fasb.org/extlink&oid=121590274&loc=SL5624163-113959 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 50 -Paragraph 3 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 55 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=99393222&loc=SL20226000-175313 + Details Name: us-gaap_DerivativeFairValueOfDerivativeLiability Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: credit Period Type: instant

X

- Definition Amount of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 45 -Paragraph 1A -URI http://asc.fasb.org/extlink&oid=99377092&loc=SL75136599-209740 + Details Name: us-gaap_EquitySecuritiesFvNi Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: instant

X

- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details Name: us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems Namespace Prefix: us-gaap_ Data Type: xbrli:stringItemType Balance Type: na Period Type: duration

X

- Definition Fair value of financial and nonfinancial obligations. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258 + Details Name: us-gaap_LiabilitiesFairValueDisclosure Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: credit Period Type: instant

X

- Definition Amount of investment in debt security measured at fair value with change in fair value recognized in net income (trading) and investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03.4) -URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878 + Details Name: us-gaap_TradingSecurities Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: instant

X

- Details Name: us-gaap_FinancialInstrumentAxis=us-gaap_USTreasuryAndGovernmentMember Namespace Prefix: Data Type: na Balance Type: Period Type:

X

- Details Name: us-gaap_FinancialInstrumentAxis=us-gaap_MortgageBackedSecuritiesMember Namespace Prefix: Data Type: na Balance Type: Period Type:

X

- Details Name: us-gaap_FairValueByMeasurementFrequencyAxis=us-gaap_FairValueMeasurementsRecurringMember Namespace Prefix: Data Type: na Balance Type: Period Type:

X

- Details Name: us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel1Member Namespace Prefix: Data Type: na Balance Type: Period Type:

X

- Details Name: us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel2Member Namespace Prefix: Data Type: na Balance Type: Period Type:

X

- Details Name: us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel3Member Namespace Prefix: Data Type: na Balance Type: Period Type:

X

- Details Name: us-gaap_DerivativeInstrumentRiskAxis=us-gaap_InterestRateContractMember Namespace Prefix: Data Type: na Balance Type: Period Type:

X

- Details Name: us-gaap_DerivativeInstrumentRiskAxis=us-gaap_CommodityContractMember Namespace Prefix: Data Type: na Balance Type: Period Type:

X

- Details Name: us-gaap_DerivativeInstrumentRiskAxis=us-gaap_ForeignExchangeContractMember Namespace Prefix: Data Type: na Balance Type: Period Type:

X

- Details Name: us-gaap_FinancialInstrumentAxis=cma_DeferredCompensationPlanAssetsMember Namespace Prefix: Data Type: na Balance Type: Period Type:

X

- Details Name: us-gaap_FinancialInstrumentAxis=us-gaap_EquitySecuritiesMember Namespace Prefix: Data Type: na Balance Type: Period Type:

v3.20.2

Fair Value Measurements (Changes In Level 3 Assets And Liabilities Measured At Fair Value On A Recurring Basis) (Details) - Interest rate contracts - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Balance at beginning of period		$ 43	$ 14	$ 22	$ 9
Realized gains (losses) recorded in earnings	[1]	0	0	0	0
Unrealized gains (losses) recorded in earnings	[1]	1	7	22	12
Payments, sales and redemptions		0	0	0	0
Balance at end of period		$ 44	$ 21	$ 44	$ 21
[1] Realized and unrealized gains and losses due to changes in fair value are recorded in other noninterest income on the Consolidated Statements of Comprehensive Income.

X

- Definition This element represents total realized gains or losses for the period, arising from assets measured at fair value on a recurring basis using unobservable inputs (Level 3), which are included in earnings or resulted in a change in net asset value. + References No definition available. + Details Name: cma_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetRealizedGainLossIncludedInEarnings Namespace Prefix: cma_ Data Type: xbrli:monetaryItemType Balance Type: credit Period Type: duration

X

- Definition This element represents total unrealized gains or losses for the period, arising from assets measured at fair value on a recurring basis using unobservable inputs (Level 3), which are included in earnings or resulted in a change in net asset value. + References No definition available. + Details Name: cma_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetUnrealizedGainLossIncludedInEarnings Namespace Prefix: cma_ Data Type: xbrli:monetaryItemType Balance Type: credit Period Type: duration

X

- Definition Amount of settlement of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258 + Details Name: us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSettlements Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: credit Period Type: duration

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- Definition Fair value of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258 + Details Name: us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: instant

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- Details Name: us-gaap_DerivativeInstrumentRiskAxis=us-gaap_InterestRateContractMember Namespace Prefix: Data Type: na Balance Type: Period Type:

v3.20.2

Fair Value Measurements (Assets And Liabilities Recorded At Fair Value On A Nonrecurring Basis) (Details) - Nonrecurring - Level 3 - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets at fair value	$ 146	$ 70
Commercial borrower | Domestic loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans	$ 146	$ 70

X

- Definition Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258 + Details Name: us-gaap_AssetsFairValueDisclosure Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: instant

X

- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details Name: us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems Namespace Prefix: us-gaap_ Data Type: xbrli:stringItemType Balance Type: na Period Type: duration

X

- Definition Fair value portion of loan receivable, including, but not limited to, mortgage loans held for investment, finance receivables held for investment, policy loans on insurance contracts. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -URI http://asc.fasb.org/subtopic&trid=2196772 + Details Name: us-gaap_LoansReceivableFairValueDisclosure Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: instant

X

- Details Name: us-gaap_FairValueByMeasurementFrequencyAxis=us-gaap_FairValueMeasurementsNonrecurringMember Namespace Prefix: Data Type: na Balance Type: Period Type:

X

- Details Name: us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel3Member Namespace Prefix: Data Type: na Balance Type: Period Type:

X

- Details Name: us-gaap_ClassOfFinancingReceivableTypeOfBorrowerAxis=us-gaap_CommercialBorrowerMember Namespace Prefix: Data Type: na Balance Type: Period Type:

X

- Details Name: us-gaap_GeographicDistributionAxis=us-gaap_GeographicDistributionDomesticMember Namespace Prefix: Data Type: na Balance Type: Period Type:

v3.20.2

Fair Value Measurements (Estimated Fair Values Of Financial Instruments Not Recorded At Fair Value In Their Entirety On A Recurring Basis) (Details) - USD ($) $ in Millions		Jun. 30, 2020	Dec. 31, 2019
Cash and due from banks		$ 1,048	$ 973
Interest-bearing deposits with banks		12,263	4,845
Total loans, net of allowance for loan losses		52,439	49,732
Demand deposits (noninterest-bearing)		35,582	27,382
Customer certificates of deposit		2,656	2,978
Other time deposits		0	133
Total deposits		67,720	57,295
Short-term borrowings		752	71
Medium- and long-term debt		6,521	7,269
Carrying Amount
Cash and due from banks		1,048	973
Interest-bearing deposits with banks		12,263	4,845
Loans held-for-sale		11	6
Total loans, net of allowance for loan losses	[1]	52,439	49,732
Customers' liability on acceptances outstanding		2	2
Restricted equity investments		269	248
Nonmarketable equity securities	[2]	5	5
Demand deposits (noninterest-bearing)		35,582	27,382
Interest-bearing deposits		29,482	26,802
Customer certificates of deposit		2,656	2,978
Other time deposits			133
Total deposits		67,720	57,295
Short-term borrowings		752	71
Acceptances outstanding		2	2
Medium- and long-term debt		6,521	7,269
Credit-related financial instruments		(81)	(57)
Estimated Fair Value
Cash and due from banks		1,048	973
Interest-bearing deposits with banks		12,263	4,845
Loans held-for-sale		11	6
Total loans, net of allowance for loan losses	[1]	52,273	49,975
Customers' liability on acceptances outstanding		2	2
Restricted equity investments		269	248
Nonmarketable equity securities	[2]	10	10
Demand deposits (noninterest-bearing)		35,582	27,382
Interest-bearing deposits		29,482	26,802
Customer certificates of deposit		2,662	2,968
Other time deposits			133
Total deposits		67,726	57,285
Short-term borrowings		752	71
Acceptances outstanding		2	2
Medium- and long-term debt		6,465	7,316
Credit-related financial instruments		(81)	(57)
Level 1 | Estimated Fair Value
Cash and due from banks		1,048	973
Interest-bearing deposits with banks		12,263	4,845
Loans held-for-sale		0	0
Total loans, net of allowance for loan losses	[1]	0	0
Customers' liability on acceptances outstanding		2	2
Restricted equity investments		269	248
Demand deposits (noninterest-bearing)		0	0
Interest-bearing deposits		0	0
Customer certificates of deposit		0	0
Other time deposits			0
Total deposits		0	0
Short-term borrowings		752	71
Acceptances outstanding		2	2
Medium- and long-term debt		0	0
Credit-related financial instruments		0	0
Level 2 | Estimated Fair Value
Cash and due from banks		0	0
Interest-bearing deposits with banks		0	0
Loans held-for-sale		11	6
Total loans, net of allowance for loan losses	[1]	0	0
Customers' liability on acceptances outstanding		0	0
Restricted equity investments		0	0
Demand deposits (noninterest-bearing)		35,582	27,382
Interest-bearing deposits		29,482	26,802
Customer certificates of deposit		2,662	2,968
Other time deposits			133
Total deposits		67,726	57,285
Short-term borrowings		0	0
Acceptances outstanding		0	0
Medium- and long-term debt		6,465	7,316
Credit-related financial instruments		0	0
Level 3 | Estimated Fair Value
Cash and due from banks		0	0
Interest-bearing deposits with banks		0	0
Loans held-for-sale		0	0
Total loans, net of allowance for loan losses	[1]	52,273	49,975
Customers' liability on acceptances outstanding		0	0
Restricted equity investments		0	0
Demand deposits (noninterest-bearing)		0	0
Interest-bearing deposits		0	0
Customer certificates of deposit		0	0
Other time deposits			0
Total deposits		0	0
Short-term borrowings		0	0
Acceptances outstanding		0	0
Medium- and long-term debt		0	0
Credit-related financial instruments		(81)	(57)
Nonrecurring
Total loans, net of allowance for loan losses		$ 146	$ 70
[1] Included $146 million and $70 million of loans recorded at fair value on a nonrecurring basis at June 30, 2020 and December 31, 2019, respectively. [2] Certain investments that are measured at fair value using the net asset value have not been classified in the fair value hierarchy. The fair value amounts presented in the table are intended to permit reconciliation of the fair value hierarchy to the amounts presented in the Consolidated Balance Sheets.

X

- Definition Value of credit-related financial instruments included in accrued expenses and other liabilities, including unused commitments to extend credit, letters of credit and financial guarantees. Includes the allowance for credit losses on lending-related commitments and the current amortized value of the guarantee liability recognized at fair value at inception of the commitment. + References No definition available. + Details Name: cma_CreditRelatedFinancialInstruments Namespace Prefix: cma_ Data Type: xbrli:monetaryItemType Balance Type: credit Period Type: instant

X

- Definition Certificates of deposit, including individual retirement accounts, other than those issued to local and national institutional depositors or acquired from brokers. + References No definition available. + Details Name: cma_DepositsCustomerCertificatesDeposits Namespace Prefix: cma_ Data Type: xbrli:monetaryItemType Balance Type: credit Period Type: instant

X

- Definition All interest-bearing deposit liabilities except for customer certificates of deposit. + References No definition available. + Details Name: cma_InterestBearingDepositLiabilitiesOtherTimeDeposit Namespace Prefix: cma_ Data Type: xbrli:monetaryItemType Balance Type: credit Period Type: instant

X

- Definition Certificates of deposit acquired from brokers or issued to local and national institutional depositors. + References No definition available. + Details Name: cma_OtherTimeDeposits Namespace Prefix: cma_ Data Type: xbrli:monetaryItemType Balance Type: credit Period Type: instant

X

- Definition Fair value of investment other than investment in equity security, investment in debt security and equity method investment. Includes, but is not limited to, investment in certain entities that calculate net asset value per share. Example includes, but is not limited to, investment in hedge fund, venture capital fund, private equity fund, and real estate partnership or fund. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 6A -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=117815213&loc=SL6742756-110258 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 35 -Paragraph 54B -URI http://asc.fasb.org/extlink&oid=117332851&loc=SL7495116-110257 + Details Name: us-gaap_AlternativeInvestment Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: instant

X

- Definition Carrying amount as of the balance sheet date of drafts and bills of exchange that have been accepted by the reporting bank, or by others for its own account, as its liability to holders of the drafts. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03.14) -URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878 + Details Name: us-gaap_BankAcceptancesExecutedAndOutstanding Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: credit Period Type: instant

X

- Definition For banks and other depository institutions: Includes cash on hand (currency and coin), cash items in process of collection, noninterest bearing deposits due from other financial institutions (including corporate credit unions), and noninterest bearing balances with the Federal Reserve Banks, Federal Home Loan Banks and central banks. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(1)) -URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878 + Details Name: us-gaap_CashAndDueFromBanks Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: instant

X

- Definition The aggregate of all deposit liabilities held by the entity, including foreign and domestic, interest and noninterest bearing; may include demand deposits, saving deposits, Negotiable Order of Withdrawal (NOW) and time deposits among others. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03.12) -URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878 + Details Name: us-gaap_Deposits Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: credit Period Type: instant

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- Definition Amounts receivable from customers on short-term negotiable time drafts drawn on and accepted by the institution (also known as banker's acceptance transactions) that are outstanding on the reporting date. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03.9) -URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878 + Details Name: us-gaap_DueFromCustomerAcceptances Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: instant

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- Definition Amount of Federal Home Loan Bank (FHLB) and Federal Reserve Bank stock. + References No definition available. + Details Name: us-gaap_FederalHomeLoanBankStockAndFederalReserveBankStock Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: instant

X

- Definition For banks and other depository institutions (including Federal Reserve Banks, if applicable): Interest-bearing deposits in other financial institutions for relatively short periods of time including, for example, certificates of deposits, which are presented separately from cash on the balance sheet. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section 45 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=117340910&loc=d3e59706-112781 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03.2) -URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878 + Details Name: us-gaap_InterestBearingDepositsInBanks Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: instant

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- Definition Amount after allowance and deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements and loans held for sale. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=121593590&loc=d3e4428-111522 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03.7) -URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878 + Details Name: us-gaap_LoansAndLeasesReceivableNetReportedAmount Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: instant

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- Definition Amount, after valuation allowance, of financing receivable held for sale and not part of disposal group. Excludes loan covered under loss sharing agreement and loan classified as investment in debt security. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=121593590&loc=d3e4428-111522 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 948 -SubTopic 310 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=120238483&loc=d3e48678-111004 + Details Name: us-gaap_LoansReceivableHeldForSaleNetNotPartOfDisposalGroup Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: instant

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- Definition Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 20 -Section 50 -Paragraph 4 -Subparagraph (b)(3) -URI http://asc.fasb.org/extlink&oid=120520924&loc=SL6031897-161870 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(a)(16)) -URI http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(16)) -URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(22)) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 + Details Name: us-gaap_LongTermDebt Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: credit Period Type: instant

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- Definition The aggregate amount of all domestic and foreign noninterest-bearing deposits liabilities held by the entity. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03.12) -URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878 + Details Name: us-gaap_NoninterestBearingDepositLiabilities Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: credit Period Type: instant

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- Definition Reflects the total carrying amount as of the balance sheet date of debt having initial terms less than one year or the normal operating cycle, if longer. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(19)(a)) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(a)(16)(a)(1)) -URI http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(13)) -URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878 + Details Name: us-gaap_ShortTermBorrowings Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: credit Period Type: instant

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- Details Name: us-gaap_FairValueByMeasurementBasisAxis=us-gaap_CarryingReportedAmountFairValueDisclosureMember Namespace Prefix: Data Type: na Balance Type: Period Type:

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v3.20.2

Investment Securities (Narrative) (Details) - USD ($) $ in Millions		Jun. 30, 2020	Dec. 31, 2019
Investment securities available-for-sale, Amortized Cost		$ 12,388	$ 12,313
Investment securities available-for-sale, Fair Value		12,759	12,398
Carrying value of securities pledged		5,700
Pledged to the FHLB as collateral for potential future borrowings		5,200
FHLB potential future borrowings		5,000
Collateral for potential future borrowings		506
Liabilities secured by pledged collateral		432
U.S. Treasury and other U.S. government agency securities
Investment securities available-for-sale, Amortized Cost		2,747	2,745
Investment securities available-for-sale, Fair Value		2,852	2,792
Residential mortgage-backed securities
Investment securities available-for-sale, Amortized Cost	[1]	9,641	9,568
Investment securities available-for-sale, Fair Value	[1]	9,907	9,606
Debt securities
Investment securities available-for-sale, Amortized Cost		12,388
Investment securities available-for-sale, Fair Value		12,759
Prepayment options | Residential mortgage-backed securities
Investment securities available-for-sale, Amortized Cost		9,600
Investment securities available-for-sale, Fair Value	[1]	9,900
Available-for-sale Securities [Member]
Interest receivable		$ 19	$ 20
[1] Issued and/or guaranteed by U.S. government agencies or U.S. government-sponsored enterprises.

X

- Definition Liabilities, primarily public and other deposits of state and local government agencies and derivative instruments, secured by pledged securities. + References No definition available. + Details Name: cma_LiabilitiesSecuredByPledgedSecurities Namespace Prefix: cma_ Data Type: xbrli:monetaryItemType Balance Type: credit Period Type: instant

X

- Definition Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading. + References No definition available. + Details Name: us-gaap_AvailableForSaleSecurities Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: instant

X

- Definition This item represents the cost of debt and equity securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any. + References No definition available. + Details Name: us-gaap_AvailableForSaleSecuritiesAmortizedCost Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: instant

X

- Definition Amount of unused borrowing capacity under the long-term financing arrangement that is available to the entity as of the balance sheet date. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22(b)) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 + Details Name: us-gaap_DebtInstrumentUnusedBorrowingCapacityAmount Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: credit Period Type: instant

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- Definition Amount of restricted investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 860 -SubTopic 30 -Section 50 -Paragraph 1A -Subparagraph (b)(1)(i) -URI http://asc.fasb.org/extlink&oid=109249958&loc=SL6224234-111729 + Details Name: us-gaap_DebtSecuritiesAvailableForSaleRestricted Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: instant

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- Definition The fair value as of the balance sheet date of financial instruments and other positions owned by the entity and pledged to counterparties as collateral, including: (1) mortgages, mortgage-backed and asset backed securities; (2) US government and agency obligations; (3) state and municipal government obligations; (4) other sovereign government debt; (5) corporate obligations; (6) corporate equities; (7) principal investments; (8) derivative contracts; and (9) physical commodities. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 860 -SubTopic 30 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=66007379&loc=d3e113888-111728 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 860 -SubTopic 30 -Section 50 -Paragraph 1A -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=109249958&loc=SL6224234-111729 + Details Name: us-gaap_FinancialInstrumentsOwnedAndPledgedAsCollateralAtFairValue Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: instant

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- Definition Carrying amount as of the balance sheet date of interest earned but not received. Also called accrued interest or accrued interest receivable. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.8) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 + Details Name: us-gaap_InterestReceivable Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: instant

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- Definition Amount of liability associated with securities borrowed from entities in exchange for collateral. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 55 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=99393222&loc=SL20226003-175313 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 50 -Paragraph 3 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312 + Details Name: us-gaap_SecuritiesBorrowedLiability Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: credit Period Type: instant

X

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v3.20.2

Investment Securities (Summary Of Investment Securities) (Details) - USD ($) $ in Millions		Jun. 30, 2020	Dec. 31, 2019
Investment securities available-for-sale, Amortized Cost		$ 12,388	$ 12,313
Investment securities available-for-sale securities, Gross Unrealized Gains		371	113
Investment securities available-for-sale securities, Gross Unrealized Losses		0	28
Investment securities available-for-sale, Fair Value		12,759	12,398
U.S. Treasury and other U.S. government agency securities
Investment securities available-for-sale, Amortized Cost		2,747	2,745
Investment securities available-for-sale securities, Gross Unrealized Gains		105	47
Investment securities available-for-sale securities, Gross Unrealized Losses		0	0
Investment securities available-for-sale, Fair Value		2,852	2,792
Residential mortgage-backed securities
Investment securities available-for-sale, Amortized Cost	[1]	9,641	9,568
Investment securities available-for-sale securities, Gross Unrealized Gains	[1]	266	66
Investment securities available-for-sale securities, Gross Unrealized Losses	[1]	0	28
Investment securities available-for-sale, Fair Value	[1]	$ 9,907	$ 9,606
[1] Issued and/or guaranteed by U.S. government agencies or U.S. government-sponsored enterprises.

X

- Definition Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading. + References No definition available. + Details Name: us-gaap_AvailableForSaleSecurities Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: instant

X

- Definition Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=121645371&loc=d3e27161-111563 + Details Name: us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: credit Period Type: instant

X

- Definition Amount before tax of unrealized loss in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale. + References No definition available. + Details Name: us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: instant

X

- Definition This item represents the cost of debt and equity securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any. + References No definition available. + Details Name: us-gaap_AvailableForSaleSecuritiesAmortizedCost Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: instant

X

- Details Name: us-gaap_FinancialInstrumentAxis=us-gaap_USTreasuryAndGovernmentMember Namespace Prefix: Data Type: na Balance Type: Period Type:

X

- Details Name: us-gaap_FinancialInstrumentAxis=us-gaap_MortgageBackedSecuritiesMember Namespace Prefix: Data Type: na Balance Type: Period Type:

v3.20.2

Investment Securities (Summary Of Investment Securities In Unrealized Loss Positions) (Details) - USD ($) $ in Millions		Jun. 30, 2020	Dec. 31, 2019
Temporarily Impaired Less than 12 months, Fair Value		$ 1	$ 1,494
Temporarily Impaired Less than 12 Months, Unrealized Losses		0	7
Temporarily Impaired 12 months or more, Fair Value		0	1,906
Temporarily Impaired 12 Months or more, Unrealized Losses		0	21
Temporarily Impaired Total, Fair Value		1	3,400
Temporarily Impaired Total, Unrealized Losses		0	28
Residential mortgage-backed securities
Temporarily Impaired Less than 12 months, Fair Value	[1]	1	1,494
Temporarily Impaired Less than 12 Months, Unrealized Losses	[1]	0	7
Temporarily Impaired 12 months or more, Fair Value	[1]	0	1,906
Temporarily Impaired 12 Months or more, Unrealized Losses	[1]	0	21
Temporarily Impaired Total, Fair Value	[1]	1	3,400
Temporarily Impaired Total, Unrealized Losses	[1]	$ 0	$ 28
[1] Issued and/or guaranteed by U.S. government agencies or U.S. government-sponsored enterprises.

X

- Definition Amount of accumulated unrealized loss on investments in debt and equity securities classified as available-for-sale that have been in a continuous loss position for twelve months or longer. + References No definition available. + Details Name: us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: instant

X

- Definition Amount of accumulated unrealized loss on investments in debt and equity securities classified as available-for-sale in a continuous loss position. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=121645371&loc=d3e27337-111563 + Details Name: us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionAccumulatedLoss Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: instant

X

- Definition This item represents the aggregate fair value of investments in debt and equity securities in an unrealized loss position which are categorized neither as held-to-maturity nor trading securities. + References No definition available. + Details Name: us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValue Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: instant

X

- Definition Amount of accumulated unrealized loss on investments in debt and equity securities classified as available-for-sale that have been in a continuous loss position for less than twelve months. + References No definition available. + Details Name: us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: instant

X

- Definition This item represents the aggregate fair value of investments in debt and equity securities categorized neither as held-to-maturity nor trading securities that have been in a continuous unrealized loss position for less than twelve months. + References No definition available. + Details Name: us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: instant

X

- Definition This item represents the aggregate fair value of investments in debt and equity securities categorized neither as held-to-maturity nor trading securities that have been in a continuous unrealized loss position for twelve months or longer. + References No definition available. + Details Name: us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: instant

X

- Details Name: us-gaap_FinancialInstrumentAxis=us-gaap_MortgageBackedSecuritiesMember Namespace Prefix: Data Type: na Balance Type: Period Type:

v3.20.2

Investment Securities Investment Securities (Summary of Net Securities Gains (Losses)) (Details) - Debt securities - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Investments, Debt, and Equity Securities [Abstract]
Securities gains	$ 1	$ 0	$ 1	$ 0
Securities losses	0	0	(1)	(8)
Net securities gains (losses)	$ 1	$ 0	$ 0	$ (8)

X

- Definition This item represents the difference between the gross realized gains and losses realized on the sale of debt or equity securities categorized neither as held-to-maturity nor trading securities. Additionally, this item would include any losses recognized for other than temporary impairments (OTTI) of the subject investments in debt and equity securities. + References No definition available. + Details Name: us-gaap_AvailableForSaleSecuritiesGrossRealizedGainLossNet Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: credit Period Type: duration

X

- Definition This item represents the gross profit realized on the sale of debt or equity securities categorized neither as held-to-maturity nor trading securities. + References No definition available. + Details Name: us-gaap_AvailableForSaleSecuritiesGrossRealizedGains Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: credit Period Type: duration

X

- Definition This item represents the gross loss realized on the sale of debt or equity securities categorized neither as held-to-maturity nor trading securities. + References No definition available. + Details Name: us-gaap_AvailableForSaleSecuritiesGrossRealizedLosses Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: duration

X

- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details Name: us-gaap_ScheduleOfGainLossOnInvestmentsIncludingMarketableSecuritiesAndInvestmentsHeldAtCostIncomeStatementReportedAmountsSummaryLineItems Namespace Prefix: us-gaap_ Data Type: xbrli:stringItemType Balance Type: na Period Type: duration

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- Details Name: us-gaap_FinancialInstrumentAxis=us-gaap_DebtSecuritiesMember Namespace Prefix: Data Type: na Balance Type: Period Type:

v3.20.2

Investment Securities (Contractual Maturity Distribution Of Debt Securities) (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Investment securities available-for-sale, Amortized Cost	$ 12,388	$ 12,313
Investment securities available-for-sale, Fair Value	12,759	$ 12,398
Debt securities
Available-for-sale, Within one year, Amortized Cost	780
Available-for-sale, After one year through five years, Amortized Cost	2,115
Available-for-sale, After five years through ten years, Amortized Cost	872
Available-for-sale, After ten years, Amortized Cost	8,621
Investment securities available-for-sale, Amortized Cost	12,388
Available-for-sale, Within one year, Fair Value	796
Available-for-sale, After one year through five years, Fair Value	2,212
Available-for-sale, After five years through ten years, Fair Value	898
Available-for-sale, After ten years, Fair Value	8,853
Investment securities available-for-sale, Fair Value	$ 12,759

X

- Definition Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading. + References No definition available. + Details Name: us-gaap_AvailableForSaleSecurities Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: instant

X

- Definition This item represents the cost of debt and equity securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any. + References No definition available. + Details Name: us-gaap_AvailableForSaleSecuritiesAmortizedCost Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: instant

X

- Definition Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing in next rolling fiscal year following latest fiscal year. For interim and annual periods when interim period is reported on rolling approach, from latest statement of financial position date. + References No definition available. + Details Name: us-gaap_AvailableForSaleSecuritiesDebtMaturitiesNextRollingTwelveMonthsAmortizedCostBasis Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: instant

X

- Definition Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing after rolling tenth fiscal year following latest fiscal year. For interim and annual periods when interim period is reported on rolling approach, from latest statement of financial position date. + References No definition available. + Details Name: us-gaap_AvailableForSaleSecuritiesDebtMaturitiesRollingAfterYearTenAmortizedCostBasis Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: instant

X

- Definition Fair value of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing after rolling tenth fiscal year following latest fiscal year. For interim and annual periods when interim period is reported on rolling approach, from latest statement of financial position date. + References No definition available. + Details Name: us-gaap_AvailableForSaleSecuritiesDebtMaturitiesRollingAfterYearTenFairValue Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: instant

X

- Definition Amortized cost of investment in debt security, measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing in rolling sixth through tenth fiscal year following latest fiscal year. For interim and annual periods when interim period is reported on rolling approach, from latest statement of financial position date. + References No definition available. + Details Name: us-gaap_AvailableForSaleSecuritiesDebtMaturitiesRollingYearSixThroughTenAmortizedCostBasis Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: instant

X

- Definition Fair value of investment in debt security, measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing in rolling sixth through tenth fiscal year following latest fiscal year. For interim and annual periods when interim period is reported on rolling approach, from latest statement of financial position date. + References No definition available. + Details Name: us-gaap_AvailableForSaleSecuritiesDebtMaturitiesRollingYearSixThroughTenFairValue Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: instant

X

- Definition Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing in next rolling fiscal year through fifth year following latest fiscal year. For interim and annual periods when interim period is reported on rolling approach, from latest statement of financial position date. + References No definition available. + Details Name: us-gaap_AvailableForSaleSecuritiesDebtMaturitiesRollingYearTwoThroughFiveAmortizedCostBasis Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: instant

X

- Definition Fair value of investment in debt security, measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing in next rolling fiscal year through fifth year following latest fiscal year. For interim and annual periods when interim period is reported on rolling approach, from latest statement of financial position date. + References No definition available. + Details Name: us-gaap_AvailableForSaleSecuritiesDebtMaturitiesRollingYearTwoThroughFiveFairValue Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: instant

X

- Definition Fair value of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing in next fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 320 -Section 50 -Paragraph 3A -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=120252992&loc=SL120269850-112803 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=121645371&loc=d3e27198-111563 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=121645371&loc=d3e27161-111563 + Details Name: us-gaap_AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearFairValue Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: instant

X

- Details Name: us-gaap_FinancialInstrumentAxis=us-gaap_DebtSecuritiesMember Namespace Prefix: Data Type: na Balance Type: Period Type:

v3.20.2

Credit Quality And Allowance For Credit Losses (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Financing Receivable, Nonaccrual, Interest Income	$ 0	$ 0	$ 0	$ 0
Retail loans secured by residential real estate in process of foreclosure	0		0		$ 0
Commitments to lend additional funds to TDR borrowers	2		2		3
Foreclosed properties	11		$ 11		11
Principal Deferrals
Minimum period loan terms were extended			90 days	90 days
Subsequent default during period	6	0	$ 15	$ 0
Interest Rate Reductions
Minimum period loan terms were extended			90 days	90 days
Subsequent default during period	0	$ 0	$ 0	$ 0
Financing Receivable Portfolio Segment [Domain]
Interest receivable	$ 132		$ 132		$ 172

X

- Definition Days that a principal or interest payment is past due to be defined as a subsequent default + References No definition available. + Details Name: cma_Dayspastduedefinedassubsequentdefault Namespace Prefix: cma_ Data Type: xbrli:durationItemType Balance Type: na Period Type: duration

X

- Definition Amount of financing receivable modified as troubled debt restructuring within previous 12 months, with subsequent payment default. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 34 -Subparagraph (a)(2) -URI http://asc.fasb.org/extlink&oid=121611835&loc=SL6953682-111524 + Details Name: us-gaap_FinancingReceivableModificationsSubsequentDefaultRecordedInvestment1 Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: duration

X

- Definition Amount of interest income on financing receivable on nonaccrual status. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 16 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=121599337&loc=SL82919258-210447 + Details Name: us-gaap_FinancingReceivableNonaccrualInterestIncome Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: credit Period Type: duration

X

- Definition Carrying amount as of the balance sheet date of all assets obtained in full or partial satisfaction of a debt arrangement through foreclosure proceedings or defeasance; includes real and personal property; equity interests in corporations, partnerships, and joint ventures; and beneficial interests in trusts. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 11 -URI http://asc.fasb.org/extlink&oid=121611835&loc=d3e5162-111524 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 45 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=121593590&loc=d3e4437-111522 + Details Name: us-gaap_ForeclosedAssets Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: instant

X

- Definition Carrying amount as of the balance sheet date of interest earned but not received. Also called accrued interest or accrued interest receivable. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.8) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 + Details Name: us-gaap_InterestReceivable Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: instant

X

- Definition Amount of unfunded portion of contractual agreement to lend funds to borrower for financing receivable modified as troubled debt restructuring. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 40 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=121585226&loc=d3e18794-111554 + Details Name: us-gaap_LoansAndLeasesReceivableImpairedCommitmentToLend Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: instant

X

- Definition Recorded investment of consumer mortgage loan receivables secured by residential real estate properties for which formal foreclosure proceedings are in process. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 35 -URI http://asc.fasb.org/extlink&oid=121611835&loc=SL49126937-111524 + Details Name: us-gaap_MortgageLoansInProcessOfForeclosureAmount Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: instant

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- Details Name: us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis=us-gaap_FinancingReceivablePortfolioSegmentDomain Namespace Prefix: Data Type: na Balance Type: Period Type:

v3.20.2

Credit Quality And Allowance For Credit Losses (Aging Analysis Of Loans) (Details) - USD ($) $ in Millions		Jun. 30, 2020	Dec. 31, 2019
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		$ 248	$ 153
Nonaccrual loans		267	199
Current loans	[1]	52,931	50,017
Total loans		53,446	50,369
30 to 59 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		130	80
60 to 89 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		77	47
90 days or more past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		41	26
Business loans | Commercial borrower
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		192	122
Nonaccrual loans		222	162
Current loans	[1]	48,982	45,800
Total loans		49,396	46,084
Business loans | Commercial borrower | 30 to 59 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		90	59
Business loans | Commercial borrower | 60 to 89 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		67	37
Business loans | Commercial borrower | 90 days or more past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		35	26
Business loans | Commercial borrower | Domestic loans
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		125	51
Nonaccrual loans		200	148
Current loans	[1]	33,501	31,274
Total loans		33,826	31,473
Business loans | Commercial borrower | Domestic loans | 30 to 59 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		48	27
Business loans | Commercial borrower | Domestic loans | 60 to 89 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		53	7
Business loans | Commercial borrower | Domestic loans | 90 days or more past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		24	17
Business loans | Commercial borrower | International loans
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		5	5
Nonaccrual loans		0	0
Current loans	[1]	1,099	1,004
Total loans		1,104	1,009
Business loans | Commercial borrower | International loans | 30 to 59 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		0	0
Business loans | Commercial borrower | International loans | 60 to 89 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		0	5
Business loans | Commercial borrower | International loans | 90 days or more past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		5	0
Business loans | Real estate construction | Commercial borrower | Domestic loans
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		19	13
Nonaccrual loans		0	0
Current loans	[1]	3,933	3,442
Total loans		3,952	3,455
Business loans | Real estate construction | Commercial borrower | Domestic loans | 30 to 59 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		16	6
Business loans | Real estate construction | Commercial borrower | Domestic loans | 60 to 89 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		3	7
Business loans | Real estate construction | Commercial borrower | Domestic loans | 90 days or more past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		0	0
Business loans | Real estate construction | Commercial borrower | Domestic loans | Commercial Real Estate business line
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing	[2]	16	6
Nonaccrual loans	[2]	0	0
Current loans	[1],[2]	3,531	3,038
Total loans	[2]	3,547	3,044
Business loans | Real estate construction | Commercial borrower | Domestic loans | Commercial Real Estate business line | 30 to 59 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing	[2]	16	6
Business loans | Real estate construction | Commercial borrower | Domestic loans | Commercial Real Estate business line | 60 to 89 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing	[2]	0	0
Business loans | Real estate construction | Commercial borrower | Domestic loans | Commercial Real Estate business line | 90 days or more past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing	[2]	0	0
Business loans | Real estate construction | Commercial borrower | Domestic loans | Other business lines
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing	[3]	3	7
Nonaccrual loans	[3]	0	0
Current loans	[1],[3]	402	404
Total loans	[3]	405	411
Business loans | Real estate construction | Commercial borrower | Domestic loans | Other business lines | 30 to 59 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing	[3]	0	0
Business loans | Real estate construction | Commercial borrower | Domestic loans | Other business lines | 60 to 89 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing	[3]	3	7
Business loans | Real estate construction | Commercial borrower | Domestic loans | Other business lines | 90 days or more past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing	[3]	0	0
Business loans | Commercial mortgage | Commercial borrower | Domestic loans
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		43	52
Nonaccrual loans		21	14
Current loans	[1]	9,861	9,493
Total loans		9,925	9,559
Business loans | Commercial mortgage | Commercial borrower | Domestic loans | 30 to 59 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		26	25
Business loans | Commercial mortgage | Commercial borrower | Domestic loans | 60 to 89 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		11	18
Business loans | Commercial mortgage | Commercial borrower | Domestic loans | 90 days or more past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		6	9
Business loans | Commercial mortgage | Commercial borrower | Domestic loans | Commercial Real Estate business line
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing	[2]	10	9
Nonaccrual loans	[2]	3	2
Current loans	[1],[2]	2,279	2,165
Total loans	[2]	2,292	2,176
Business loans | Commercial mortgage | Commercial borrower | Domestic loans | Commercial Real Estate business line | 30 to 59 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing	[2]	1	9
Business loans | Commercial mortgage | Commercial borrower | Domestic loans | Commercial Real Estate business line | 60 to 89 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing	[2]	9	0
Business loans | Commercial mortgage | Commercial borrower | Domestic loans | Commercial Real Estate business line | 90 days or more past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing	[2]	0	0
Business loans | Commercial mortgage | Commercial borrower | Domestic loans | Other business lines
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing	[3]	33	43
Nonaccrual loans	[3]	18	12
Current loans	[1],[3]	7,582	7,328
Total loans	[3]	7,633	7,383
Business loans | Commercial mortgage | Commercial borrower | Domestic loans | Other business lines | 30 to 59 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing	[3]	25	16
Business loans | Commercial mortgage | Commercial borrower | Domestic loans | Other business lines | 60 to 89 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing	[3]	2	18
Business loans | Commercial mortgage | Commercial borrower | Domestic loans | Other business lines | 90 days or more past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing	[3]	6	9
Business loans | Lease financing | Commercial borrower | Domestic loans
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		0	1
Nonaccrual loans		1	0
Current loans	[1]	588	587
Total loans		589	588
Business loans | Lease financing | Commercial borrower | Domestic loans | 30 to 59 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		0	1
Business loans | Lease financing | Commercial borrower | Domestic loans | 60 to 89 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		0	0
Business loans | Lease financing | Commercial borrower | Domestic loans | 90 days or more past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		0	0
Retail loans
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		56	31
Nonaccrual loans		45	37
Current loans	[1]	3,949	4,217
Total loans		4,050	4,285
Retail loans | 30 to 59 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		40	21
Retail loans | 60 to 89 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		10	10
Retail loans | 90 days or more past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		6	0
Retail loans | Consumer borrower
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		20	14
Nonaccrual loans		21	17
Current loans	[1]	2,123	2,409
Total loans		2,164	2,440
Retail loans | Consumer borrower | 30 to 59 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		13	6
Retail loans | Consumer borrower | 60 to 89 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		1	8
Retail loans | Consumer borrower | 90 days or more past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		6	0
Retail loans | Residential mortgage
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		36	17
Nonaccrual loans		24	20
Current loans	[1]	1,826	1,808
Total loans		1,886	1,845
Retail loans | Residential mortgage | 30 to 59 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		27	15
Retail loans | Residential mortgage | 60 to 89 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		9	2
Retail loans | Residential mortgage | 90 days or more past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		0	0
Retail loans | Home equity | Consumer borrower
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		13	9
Nonaccrual loans		21	17
Current loans	[1]	1,635	1,685
Total loans		1,669	1,711
Retail loans | Home equity | Consumer borrower | 30 to 59 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		12	4
Retail loans | Home equity | Consumer borrower | 60 to 89 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		1	5
Retail loans | Home equity | Consumer borrower | 90 days or more past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		0	0
Retail loans | Other consumer | Consumer borrower
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		7	5
Nonaccrual loans		0	0
Current loans	[1]	488	724
Total loans		495	729
Retail loans | Other consumer | Consumer borrower | 30 to 59 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		1	2
Retail loans | Other consumer | Consumer borrower | 60 to 89 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		0	3
Retail loans | Other consumer | Consumer borrower | 90 days or more past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		$ 6	$ 0
[1] Includes $4.5 billion of loans with deferred payments not considered past due in accordance with the Coronavirus Aid, Relief, and Economic Security Act (CARES Act) at June 30, 2020. [2] Primarily loans to real estate developers. [3] Primarily loans secured by owner-occupied real estate.

X

- Definition Amount of financing receivable not past due. + References Reference 1: http://fasb.org/us-gaap/role/ref/otherTransitionRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 7A -URI http://asc.fasb.org/extlink&oid=121611835&loc=SL6953401-111524 Reference 2: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 55 -Paragraph 80 -URI http://asc.fasb.org/extlink&oid=121647567&loc=SL82922355-210448 Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 14 -URI http://asc.fasb.org/extlink&oid=121599337&loc=SL82919253-210447 + Details Name: us-gaap_FinancingReceivableRecordedInvestmentCurrent Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: instant

X

- Definition Amount of financing receivable past due. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 55 -Paragraph 80 -URI http://asc.fasb.org/extlink&oid=121647567&loc=SL82922355-210448 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 14 -URI http://asc.fasb.org/extlink&oid=121599337&loc=SL82919253-210447 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 7A -URI http://asc.fasb.org/extlink&oid=121611835&loc=SL6953401-111524 + Details Name: us-gaap_FinancingReceivableRecordedInvestmentPastDue Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: instant

X

- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details Name: us-gaap_FinancingReceivableRecordedInvestmentPastDueLineItems Namespace Prefix: us-gaap_ Data Type: xbrli:stringItemType Balance Type: na Period Type: duration

X

- Definition Reflects the carrying amount of loans deemed to be questionable as to collection on which no interest is continuing to be recognized. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 7 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=121611835&loc=d3e5111-111524 + Details Name: us-gaap_LoansAndLeasesReceivableImpairedNonperformingNonaccrualOfInterest Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: instant

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- Details Name: us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=cma_ConsumerFinancingReceivableMember Namespace Prefix: Data Type: na Balance Type: Period Type:

v3.20.2

Credit Quality And Allowance For Credit Losses (Loans By Credit Quality Indicator and Vintage Year) (Details) - USD ($) $ in Millions		Jun. 30, 2020	Dec. 31, 2019
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans		$ 53,446	$ 50,369
Financing Receivable, Originated in Current Fiscal Year		6,984
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year		6,332
Financing Receivable, Originated Two Years before Latest Fiscal Year		5,056
Financing Receivable, Originated Three Years before Latest Fiscal Year		3,920
Financing Receivable, Originated Four Years before Latest Fiscal Year		2,389
Financing Receivable, Originated Five or More Years before Latest Fiscal Year		5,322
Financing Receivable, Revolving		23,337
Financing Receivable, Revolving Converted to Term		106
Business loans | Commercial borrower
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans		49,396	46,084
Financing Receivable, Originated in Current Fiscal Year		6,616
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year		6,001
Financing Receivable, Originated Two Years before Latest Fiscal Year		4,880
Financing Receivable, Originated Three Years before Latest Fiscal Year		3,607
Financing Receivable, Originated Four Years before Latest Fiscal Year		2,125
Financing Receivable, Originated Five or More Years before Latest Fiscal Year		4,685
Financing Receivable, Revolving		21,464
Financing Receivable, Revolving Converted to Term		18
Business loans | Commercial borrower | Domestic loans
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans		33,826	31,473
Financing Receivable, Originated in Current Fiscal Year		5,059
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year		2,978
Financing Receivable, Originated Two Years before Latest Fiscal Year		2,115
Financing Receivable, Originated Three Years before Latest Fiscal Year		1,406
Financing Receivable, Originated Four Years before Latest Fiscal Year		676
Financing Receivable, Originated Five or More Years before Latest Fiscal Year		1,171
Financing Receivable, Revolving		20,403
Financing Receivable, Revolving Converted to Term		18
Business loans | Commercial borrower | Domestic loans | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[1]	31,099	29,785
Financing Receivable, Originated in Current Fiscal Year	[1],[2]	5,029
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	[1]	2,673
Financing Receivable, Originated Two Years before Latest Fiscal Year	[1]	1,876
Financing Receivable, Originated Three Years before Latest Fiscal Year	[1]	1,259
Financing Receivable, Originated Four Years before Latest Fiscal Year	[1]	572
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	[1]	966
Financing Receivable, Revolving	[1]	18,708
Financing Receivable, Revolving Converted to Term	[1]	16
Business loans | Commercial borrower | Domestic loans | Criticized
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[3]	2,727	1,688
Financing Receivable, Originated in Current Fiscal Year	[3]	30
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	[3]	305
Financing Receivable, Originated Two Years before Latest Fiscal Year	[3]	239
Financing Receivable, Originated Three Years before Latest Fiscal Year	[3]	147
Financing Receivable, Originated Four Years before Latest Fiscal Year	[3]	104
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	[3]	205
Financing Receivable, Revolving	[3]	1,695
Financing Receivable, Revolving Converted to Term	[3]	2
Business loans | Commercial borrower | International loans
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans		1,104	1,009
Financing Receivable, Originated in Current Fiscal Year		277
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year		185
Financing Receivable, Originated Two Years before Latest Fiscal Year		129
Financing Receivable, Originated Three Years before Latest Fiscal Year		23
Financing Receivable, Originated Four Years before Latest Fiscal Year		11
Financing Receivable, Originated Five or More Years before Latest Fiscal Year		77
Financing Receivable, Revolving		402
Financing Receivable, Revolving Converted to Term		0
Business loans | Commercial borrower | International loans | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[1]	1,051	972
Financing Receivable, Originated in Current Fiscal Year	[1]	272
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	[1]	185
Financing Receivable, Originated Two Years before Latest Fiscal Year	[1]	129
Financing Receivable, Originated Three Years before Latest Fiscal Year	[1]	13
Financing Receivable, Originated Four Years before Latest Fiscal Year	[1]	3
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	[1]	75
Financing Receivable, Revolving	[1]	374
Financing Receivable, Revolving Converted to Term	[1]	0
Business loans | Commercial borrower | International loans | Criticized
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[3]	53	37
Financing Receivable, Originated in Current Fiscal Year	[3]	5
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	[3]	0
Financing Receivable, Originated Two Years before Latest Fiscal Year	[3]	0
Financing Receivable, Originated Three Years before Latest Fiscal Year	[3]	10
Financing Receivable, Originated Four Years before Latest Fiscal Year	[3]	8
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	[3]	2
Financing Receivable, Revolving	[3]	28
Financing Receivable, Revolving Converted to Term	[3]	0
Business loans | Real estate construction | Commercial borrower | Domestic loans
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans		3,952	3,455
Financing Receivable, Originated in Current Fiscal Year		127
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year		880
Financing Receivable, Originated Two Years before Latest Fiscal Year		1,297
Financing Receivable, Originated Three Years before Latest Fiscal Year		819
Financing Receivable, Originated Four Years before Latest Fiscal Year		458
Financing Receivable, Originated Five or More Years before Latest Fiscal Year		219
Financing Receivable, Revolving		152
Financing Receivable, Revolving Converted to Term		0
Business loans | Real estate construction | Commercial borrower | Domestic loans | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[1]	3,921	3,424
Financing Receivable, Originated in Current Fiscal Year	[1]	127
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	[1]	878
Financing Receivable, Originated Two Years before Latest Fiscal Year	[1]	1,293
Financing Receivable, Originated Three Years before Latest Fiscal Year	[1]	795
Financing Receivable, Originated Four Years before Latest Fiscal Year	[1]	458
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	[1]	218
Financing Receivable, Revolving	[1]	152
Financing Receivable, Revolving Converted to Term	[1]	0
Business loans | Real estate construction | Commercial borrower | Domestic loans | Criticized
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[3]	31	31
Financing Receivable, Originated in Current Fiscal Year	[3]	0
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	[3]	2
Financing Receivable, Originated Two Years before Latest Fiscal Year	[3]	4
Financing Receivable, Originated Three Years before Latest Fiscal Year	[3]	24
Financing Receivable, Originated Four Years before Latest Fiscal Year	[3]	0
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	[3]	1
Financing Receivable, Revolving	[3]	0
Financing Receivable, Revolving Converted to Term	[3]	0
Business loans | Commercial mortgage | Commercial borrower | Domestic loans
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans		9,925	9,559
Financing Receivable, Originated in Current Fiscal Year		1,089
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year		1,809
Financing Receivable, Originated Two Years before Latest Fiscal Year		1,252
Financing Receivable, Originated Three Years before Latest Fiscal Year		1,301
Financing Receivable, Originated Four Years before Latest Fiscal Year		962
Financing Receivable, Originated Five or More Years before Latest Fiscal Year		3,005
Financing Receivable, Revolving		507
Financing Receivable, Revolving Converted to Term		0
Business loans | Commercial mortgage | Commercial borrower | Domestic loans | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[1]	9,449	9,262
Financing Receivable, Originated in Current Fiscal Year	[1]	1,058
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	[1]	1,713
Financing Receivable, Originated Two Years before Latest Fiscal Year	[1]	1,220
Financing Receivable, Originated Three Years before Latest Fiscal Year	[1]	1,254
Financing Receivable, Originated Four Years before Latest Fiscal Year	[1]	915
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	[1]	2,790
Financing Receivable, Revolving	[1]	499
Financing Receivable, Revolving Converted to Term	[1]	0
Business loans | Commercial mortgage | Commercial borrower | Domestic loans | Criticized
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[3]	476	297
Financing Receivable, Originated in Current Fiscal Year	[3]	31
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	[3]	96
Financing Receivable, Originated Two Years before Latest Fiscal Year	[3]	32
Financing Receivable, Originated Three Years before Latest Fiscal Year	[3]	47
Financing Receivable, Originated Four Years before Latest Fiscal Year	[3]	47
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	[3]	215
Financing Receivable, Revolving	[3]	8
Financing Receivable, Revolving Converted to Term	[3]	0
Business loans | Lease financing | Commercial borrower | Domestic loans
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans		589	588
Financing Receivable, Originated in Current Fiscal Year		64
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year		149
Financing Receivable, Originated Two Years before Latest Fiscal Year		87
Financing Receivable, Originated Three Years before Latest Fiscal Year		58
Financing Receivable, Originated Four Years before Latest Fiscal Year		18
Financing Receivable, Originated Five or More Years before Latest Fiscal Year		213
Financing Receivable, Revolving		0
Financing Receivable, Revolving Converted to Term		0
Business loans | Lease financing | Commercial borrower | Domestic loans | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[1]	564	579
Financing Receivable, Originated in Current Fiscal Year	[1]	63
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	[1]	131
Financing Receivable, Originated Two Years before Latest Fiscal Year	[1]	84
Financing Receivable, Originated Three Years before Latest Fiscal Year	[1]	56
Financing Receivable, Originated Four Years before Latest Fiscal Year	[1]	17
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	[1]	213
Financing Receivable, Revolving	[1]	0
Financing Receivable, Revolving Converted to Term	[1]	0
Business loans | Lease financing | Commercial borrower | Domestic loans | Criticized
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[3]	25	9
Financing Receivable, Originated in Current Fiscal Year	[3]	1
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	[3]	18
Financing Receivable, Originated Two Years before Latest Fiscal Year	[3]	3
Financing Receivable, Originated Three Years before Latest Fiscal Year	[3]	2
Financing Receivable, Originated Four Years before Latest Fiscal Year	[3]	1
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	[3]	0
Financing Receivable, Revolving	[3]	0
Financing Receivable, Revolving Converted to Term	[3]	0
Retail loans
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans		4,050	4,285
Financing Receivable, Originated in Current Fiscal Year		368
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year		331
Financing Receivable, Originated Two Years before Latest Fiscal Year		176
Financing Receivable, Originated Three Years before Latest Fiscal Year		313
Financing Receivable, Originated Four Years before Latest Fiscal Year		264
Financing Receivable, Originated Five or More Years before Latest Fiscal Year		637
Financing Receivable, Revolving		1,873
Financing Receivable, Revolving Converted to Term		88
Retail loans | Consumer borrower
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans		2,164	2,440
Financing Receivable, Originated in Current Fiscal Year		13
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year		80
Financing Receivable, Originated Two Years before Latest Fiscal Year		22
Financing Receivable, Originated Three Years before Latest Fiscal Year		4
Financing Receivable, Originated Four Years before Latest Fiscal Year		6
Financing Receivable, Originated Five or More Years before Latest Fiscal Year		78
Financing Receivable, Revolving		1,873
Financing Receivable, Revolving Converted to Term		88
Retail loans | Residential mortgage
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans		1,886	1,845
Financing Receivable, Originated in Current Fiscal Year		355
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year		251
Financing Receivable, Originated Two Years before Latest Fiscal Year		154
Financing Receivable, Originated Three Years before Latest Fiscal Year		309
Financing Receivable, Originated Four Years before Latest Fiscal Year		258
Financing Receivable, Originated Five or More Years before Latest Fiscal Year		559
Financing Receivable, Revolving		0
Financing Receivable, Revolving Converted to Term		0
Retail loans | Residential mortgage | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[1]	1,853	1,823
Financing Receivable, Originated in Current Fiscal Year	[1]	355
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	[1]	251
Financing Receivable, Originated Two Years before Latest Fiscal Year	[1]	149
Financing Receivable, Originated Three Years before Latest Fiscal Year	[1]	305
Financing Receivable, Originated Four Years before Latest Fiscal Year	[1]	255
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	[1]	538
Financing Receivable, Revolving	[1]	0
Financing Receivable, Revolving Converted to Term	[1]	0
Retail loans | Residential mortgage | Criticized
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[3]	33	22
Financing Receivable, Originated in Current Fiscal Year	[3]	0
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	[3]	0
Financing Receivable, Originated Two Years before Latest Fiscal Year	[3]	5
Financing Receivable, Originated Three Years before Latest Fiscal Year	[3]	4
Financing Receivable, Originated Four Years before Latest Fiscal Year	[3]	3
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	[3]	21
Financing Receivable, Revolving	[3]	0
Financing Receivable, Revolving Converted to Term	[3]	0
Retail loans | Home equity | Consumer borrower
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans		1,669	1,711
Financing Receivable, Originated in Current Fiscal Year		0
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year		0
Financing Receivable, Originated Two Years before Latest Fiscal Year		0
Financing Receivable, Originated Three Years before Latest Fiscal Year		0
Financing Receivable, Originated Four Years before Latest Fiscal Year		0
Financing Receivable, Originated Five or More Years before Latest Fiscal Year		20
Financing Receivable, Revolving		1,561
Financing Receivable, Revolving Converted to Term		88
Retail loans | Home equity | Consumer borrower | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[1]	1,645	1,682
Financing Receivable, Originated in Current Fiscal Year	[1]	0
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	[1]	0
Financing Receivable, Originated Two Years before Latest Fiscal Year	[1]	0
Financing Receivable, Originated Three Years before Latest Fiscal Year	[1]	0
Financing Receivable, Originated Four Years before Latest Fiscal Year	[1]	0
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	[1]	19
Financing Receivable, Revolving	[1]	1,544
Financing Receivable, Revolving Converted to Term	[1]	82
Retail loans | Home equity | Consumer borrower | Criticized
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[3]	24	29
Financing Receivable, Originated in Current Fiscal Year	[3]	0
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	[3]	0
Financing Receivable, Originated Two Years before Latest Fiscal Year	[3]	0
Financing Receivable, Originated Three Years before Latest Fiscal Year	[3]	0
Financing Receivable, Originated Four Years before Latest Fiscal Year	[3]	0
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	[3]	1
Financing Receivable, Revolving	[3]	17
Financing Receivable, Revolving Converted to Term	[3]	6
Retail loans | Other consumer | Consumer borrower
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans		495	729
Financing Receivable, Originated in Current Fiscal Year		13
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year		80
Financing Receivable, Originated Two Years before Latest Fiscal Year		22
Financing Receivable, Originated Three Years before Latest Fiscal Year		4
Financing Receivable, Originated Four Years before Latest Fiscal Year		6
Financing Receivable, Originated Five or More Years before Latest Fiscal Year		58
Financing Receivable, Revolving		312
Financing Receivable, Revolving Converted to Term		0
Retail loans | Other consumer | Consumer borrower | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[1]	485	722
Financing Receivable, Originated in Current Fiscal Year	[1]	13
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	[1]	79
Financing Receivable, Originated Two Years before Latest Fiscal Year	[1]	19
Financing Receivable, Originated Three Years before Latest Fiscal Year	[1]	4
Financing Receivable, Originated Four Years before Latest Fiscal Year	[1]	6
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	[1]	58
Financing Receivable, Revolving	[1]	306
Financing Receivable, Revolving Converted to Term	[1]	0
Retail loans | Other consumer | Consumer borrower | Criticized
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[3]	10	$ 7
Financing Receivable, Originated in Current Fiscal Year	[3]	0
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	[3]	1
Financing Receivable, Originated Two Years before Latest Fiscal Year	[3]	3
Financing Receivable, Originated Three Years before Latest Fiscal Year	[3]	0
Financing Receivable, Originated Four Years before Latest Fiscal Year	[3]	0
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	[3]	0
Financing Receivable, Revolving	[3]	6
Financing Receivable, Revolving Converted to Term	[3]	$ 0
[1] Includes all loans not included in the categories of special mention, substandard or nonaccrual. [2] Includes $3.8 billion of Small Business Administration Paycheck Protection Program (PPP) loans at June 30, 2020. [3] Includes loans with an internal rating of special mention, substandard loans for which the accrual of interest has not been discontinued and nonaccrual loans. Special mention loans have potential credit weaknesses that deserve management’s close attention, such as loans to borrowers who may be experiencing financial difficulties that may result in deterioration of repayment prospects from the borrower at some future date. Accruing substandard loans have a well-defined weakness, or weaknesses, such as loans to borrowers who may be experiencing losses from operations or inadequate liquidity of a degree and duration that jeopardizes the orderly repayment of the loan. Substandard loans are also distinguished by the distinct possibility of loss in the future if these weaknesses are not corrected. Nonaccrual loans are loans for which the accrual of interest has been discontinued. For further information regarding nonaccrual loans, refer to the Nonperforming Assets subheading in Note 1 - Basis of Presentation and Accounting Policies - on page F-51 in the Corporation's 2019 Annual Report. These categories are generally consistent with the "special mention" and "substandard" categories as defined by regulatory authorities. A minority of nonaccrual loans are consistent with the "doubtful" category.

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- Definition Financing Receivable, Revolving Converted to Term + References No definition available. + Details Name: cma_FinancingReceivableRevolvingConvertedtoTerm Namespace Prefix: cma_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: instant

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- Definition Amount of financing receivable originated more than five years prior to current fiscal year. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 55 -Paragraph 79 -URI http://asc.fasb.org/extlink&oid=121647567&loc=SL82922352-210448 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=121599337&loc=SL82919232-210447 + Details Name: us-gaap_FinancingReceivableOriginatedFiveOrMoreYearsBeforeLatestFiscalYear Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: instant

X

- Definition Amount of financing receivable originated four years prior to current fiscal year. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 55 -Paragraph 79 -URI http://asc.fasb.org/extlink&oid=121647567&loc=SL82922352-210448 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=121599337&loc=SL82919232-210447 + Details Name: us-gaap_FinancingReceivableOriginatedFourYearsBeforeLatestFiscalYear Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: instant

X

- Definition Amount of financing receivable originated in current fiscal year. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 55 -Paragraph 79 -URI http://asc.fasb.org/extlink&oid=121647567&loc=SL82922352-210448 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=121599337&loc=SL82919232-210447 + Details Name: us-gaap_FinancingReceivableOriginatedInCurrentFiscalYear Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: instant

X

- Definition Amount of financing receivable originated in fiscal year prior to current fiscal year. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=121599337&loc=SL82919232-210447 Reference 2: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 55 -Paragraph 79 -URI http://asc.fasb.org/extlink&oid=121647567&loc=SL82922352-210448 + Details Name: us-gaap_FinancingReceivableOriginatedInFiscalYearBeforeLatestFiscalYear Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: instant

X

- Definition Amount of financing receivable originated three years prior to current fiscal year. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 55 -Paragraph 79 -URI http://asc.fasb.org/extlink&oid=121647567&loc=SL82922352-210448 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=121599337&loc=SL82919232-210447 + Details Name: us-gaap_FinancingReceivableOriginatedThreeYearsBeforeLatestFiscalYear Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: instant

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- Definition Amount of financing receivable originated two years prior to current fiscal year. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 55 -Paragraph 79 -URI http://asc.fasb.org/extlink&oid=121647567&loc=SL82922352-210448 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=121599337&loc=SL82919232-210447 + Details Name: us-gaap_FinancingReceivableOriginatedTwoYearsBeforeLatestFiscalYear Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: instant

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X

- Definition Amount of financing receivable that can be withdrawn, repaid and redrawn. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=121599337&loc=SL82919232-210447 Reference 2: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 55 -Paragraph 79 -URI http://asc.fasb.org/extlink&oid=121647567&loc=SL82922352-210448 + Details Name: us-gaap_FinancingReceivableRevolving Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: instant

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- Definition Amount before allowance and after deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=121593590&loc=d3e4428-111522 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=121611835&loc=d3e5074-111524 + Details Name: us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: instant

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v3.20.2

Credit Quality And Allowance For Credit Losses (Changes In The Allowance For Loan Losses And Related Loan Amounts) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Jan. 01, 2020	Jan. 01, 2019
Financing Receivable, Allowance for Credit Loss [Line Items]
Balance at beginning of period	$ 978	$ 677	$ 668	$ 701
Increase in retail loans allowance for credit losses					$ 25
Provision for credit losses	138	44	549	31
Balance at end of period	$ 1,066	$ 688	$ 1,066	$ 688
As a percentage of total loans	1.99%	1.33%	1.99%	1.33%
As a percentage of total loans excluding PPP Loans	2.15%		2.15%
Accounting Standards Update 2016-13 [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Reduction in business loans allowance for credit losses					(42)	$ 0
Increase in retail loans allowance for credit losses					25	0
Day-one decrease in the overall allowance for credit losses					$ (17)	$ 0
Financing Receivable
Financing Receivable, Allowance for Credit Loss [Line Items]
Balance at beginning of period	$ 916	$ 647	$ 637	$ 671
Loan charge-offs	(57)	(44)	(146)	(64)
Recoveries on loans previously charged-off	7	11	12	20
Net loan charge-offs	(50)	(33)	(134)	(44)
Provision for credit losses	141	43	521	30
Balance at end of period	$ 1,007	$ 657	$ 1,007	$ 657
As a percentage of total loans	1.88%	1.27%	1.88%	1.27%
As a percentage of total loans excluding PPP Loans	2.03%		2.03%
Unused Commitments to Extend Credit
Financing Receivable, Allowance for Credit Loss [Line Items]
Balance at beginning of period	$ 62	$ 30	$ 31	$ 30
Provision for credit losses	(3)	1	28	1
Balance at end of period	59	31	59	31
Business loans
Financing Receivable, Allowance for Credit Loss [Line Items]
Balance at beginning of period	913	635	629	653
Provision for credit losses	130	44	538	37
Balance at end of period	$ 993	$ 646	$ 993	$ 646
As a percentage of total loans	2.01%	1.36%	2.01%	1.36%
As a percentage of total loans excluding PPP Loans	2.18%		2.18%
Business loans | Financing Receivable
Financing Receivable, Allowance for Credit Loss [Line Items]
Balance at beginning of period	$ 861	$ 608	$ 601	$ 627
Loan charge-offs	(56)	(43)	(143)	(62)
Recoveries on loans previously charged-off	6	10	11	18
Net loan charge-offs	(50)	(33)	(132)	(44)
Provision for credit losses	132	43	516	35
Balance at end of period	$ 943	$ 618	$ 943	$ 618
As a percentage of total loans	1.91%	1.30%	1.91%	1.30%
As a percentage of total loans excluding PPP Loans	2.07%		2.07%
Business loans | Unused Commitments to Extend Credit
Financing Receivable, Allowance for Credit Loss [Line Items]
Balance at beginning of period	$ 52	$ 27	$ 28	$ 26
Provision for credit losses	(2)	1	22	2
Balance at end of period	50	28	50	28
Retail loans
Financing Receivable, Allowance for Credit Loss [Line Items]
Balance at beginning of period	65	42	39	48
Provision for credit losses	8	0	11	6
Balance at end of period	$ 73	$ 42	$ 73	$ 42
As a percentage of total loans	1.82%	0.96%	1.82%	0.96%
Retail loans | Financing Receivable
Financing Receivable, Allowance for Credit Loss [Line Items]
Balance at beginning of period	$ 55	$ 39	$ 36	$ 44
Loan charge-offs	(1)	(1)	(3)	(2)
Recoveries on loans previously charged-off	1	1	1	2
Net loan charge-offs	0	0	(2)	0
Provision for credit losses	9	0	5	5
Balance at end of period	$ 64	$ 39	$ 64	$ 39
As a percentage of total loans	1.59%	0.89%	1.59%	0.89%
Retail loans | Unused Commitments to Extend Credit
Financing Receivable, Allowance for Credit Loss [Line Items]
Balance at beginning of period	$ 10	$ 3	$ 3	$ 4
Provision for credit losses	(1)	0	6	(1)
Balance at end of period	$ 9	$ 3	$ 9	$ 3

X

- Definition Day-one decrease in the overall allowance for credit losses + References No definition available. + Details Name: cma_Dayonedecreaseintheoverallallowanceforcreditlosses Namespace Prefix: cma_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: instant

X

- Definition The ratio of Allowance for Credit Losses to All Loans. + References No definition available. + Details Name: cma_FinancingReceivableRatioOfAllowanceForCreditLossesToAllLoans Namespace Prefix: cma_ Data Type: num:percentItemType Balance Type: na Period Type: instant

X

- Definition Financing Receivable, Ratio of Allowance for Loan Losses to All Loans excluding PPP Loans + References No definition available. + Details Name: cma_FinancingReceivableRatioOfAllowanceForLoanLossesToAllLoansExcludingPPPLoans Namespace Prefix: cma_ Data Type: num:percentItemType Balance Type: na Period Type: instant

X

- Definition Increase in retail loans allowance for credit losses + References No definition available. + Details Name: cma_Increaseinretailloansallowanceforcreditlosses Namespace Prefix: cma_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: instant

X

- Definition Reduction in business loans allowance for credit losses + References No definition available. + Details Name: cma_Reductioninbusinessloansallowanceforcreditlosses Namespace Prefix: cma_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: instant

X

- Definition Amount, after recoveries, of loans and leases that have been written-off. + References No definition available. + Details Name: us-gaap_AllowanceForLoanAndLeaseLossesWriteoffsNet Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: duration

X

- Definition Amount of allowance for credit loss on financing receivable. Excludes allowance for financing receivable covered under loss sharing agreement. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 11B -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=121611835&loc=SL6953423-111524 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(7)(2)) -URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=121599878&loc=SL82895884-210446 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 13 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=121599337&loc=SL82919249-210447 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 13 -Subparagraph (f) -URI http://asc.fasb.org/extlink&oid=121599337&loc=SL82919249-210447 + Details Name: us-gaap_FinancingReceivableAllowanceForCreditLosses Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: credit Period Type: instant

X

- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details Name: us-gaap_FinancingReceivableAllowanceForCreditLossesLineItems Namespace Prefix: us-gaap_ Data Type: xbrli:stringItemType Balance Type: na Period Type: duration

X

- Definition Amount of increase in allowance for credit loss on financing receivable from recovery. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 55 -Paragraph 79 -URI http://asc.fasb.org/extlink&oid=121647567&loc=SL82922352-210448 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 13 -Subparagraph (e) -URI http://asc.fasb.org/extlink&oid=121599337&loc=SL82919249-210447 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 11B -Subparagraph (c)(4) -URI http://asc.fasb.org/extlink&oid=121611835&loc=SL6953423-111524 + Details Name: us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: credit Period Type: duration

X

- Definition Amount of writeoff of financing receivable, charged against allowance for credit loss. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 13 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=121599337&loc=SL82919249-210447 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 11B -Subparagraph (c)(3) -URI http://asc.fasb.org/extlink&oid=121611835&loc=SL6953423-111524 Reference 3: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 55 -Paragraph 79 -URI http://asc.fasb.org/extlink&oid=121647567&loc=SL82922352-210448 + Details Name: us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: duration

X

- Definition Amount of expense related loan transactions, lease transactions, credit loss from transactions other than loan and lease transactions, and other loss based on assessment of uncollectability from the counterparty to reduce the account to their net realizable value. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 11B -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=121611835&loc=SL6953423-111524 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 220 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-04.11) -URI http://asc.fasb.org/extlink&oid=120399700&loc=SL114874048-224260 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3602-108585 + Details Name: us-gaap_ProvisionForLoanLeaseAndOtherLosses Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: duration

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- Details Name: us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis=us-gaap_CommitmentsToExtendCreditMember Namespace Prefix: Data Type: na Balance Type: Period Type:

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- Details Name: us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_CommercialPortfolioSegmentMember Namespace Prefix: Data Type: na Balance Type: Period Type:

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- Details Name: us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_ConsumerPortfolioSegmentMember Namespace Prefix: Data Type: na Balance Type: Period Type:

v3.20.2

Credit Quality And Allowance For Credit Losses (Nonaccrual Loans) (Details) - USD ($) $ in Millions		Jun. 30, 2020	Dec. 31, 2019
Financing Receivable, Nonaccrual [Line Items]
Financing Receivable, Nonaccrual, No Allowance		$ 85	$ 69
Financing Receivable, Nonaccrual		182	130
Nonaccrual loans		267	199
Business loans | Commercial borrower
Financing Receivable, Nonaccrual [Line Items]
Financing Receivable, Nonaccrual, No Allowance		40	32
Financing Receivable, Nonaccrual		182	130
Nonaccrual loans		222	162
Business loans | Commercial borrower | Domestic loans
Financing Receivable, Nonaccrual [Line Items]
Financing Receivable, Nonaccrual, No Allowance		32	29
Financing Receivable, Nonaccrual		168	119
Nonaccrual loans		200	148
Business loans | Commercial borrower | International loans
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual loans		0	0
Retail loans
Financing Receivable, Nonaccrual [Line Items]
Financing Receivable, Nonaccrual, No Allowance		45	37
Financing Receivable, Nonaccrual		0	0
Nonaccrual loans		45	37
Retail loans | Consumer borrower
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual loans		21	17
Commercial mortgage | Business loans | Commercial borrower | Domestic loans
Financing Receivable, Nonaccrual [Line Items]
Financing Receivable, Nonaccrual, No Allowance		8	3
Financing Receivable, Nonaccrual		13	11
Nonaccrual loans		21	14
Commercial mortgage | Commercial Real Estate business line | Business loans | Commercial borrower | Domestic loans
Financing Receivable, Nonaccrual [Line Items]
Financing Receivable, Nonaccrual, No Allowance	[1]	2	2
Financing Receivable, Nonaccrual	[1]	1	0
Nonaccrual loans	[1]	3	2
Commercial mortgage | Other business lines | Business loans | Commercial borrower | Domestic loans
Financing Receivable, Nonaccrual [Line Items]
Financing Receivable, Nonaccrual, No Allowance	[2]	6	1
Financing Receivable, Nonaccrual	[2]	12	11
Nonaccrual loans	[2]	18	12
Residential mortgage | Retail loans
Financing Receivable, Nonaccrual [Line Items]
Financing Receivable, Nonaccrual, No Allowance		24	20
Financing Receivable, Nonaccrual		0	0
Nonaccrual loans		24	20
Home equity | Retail loans | Consumer borrower
Financing Receivable, Nonaccrual [Line Items]
Financing Receivable, Nonaccrual, No Allowance		21	17
Financing Receivable, Nonaccrual		0	0
Nonaccrual loans		21	17
Other consumer | Retail loans | Consumer borrower
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual loans		0	$ 0
Business Loans | Finance Leases Portfolio Segment [Member] | Commercial borrower | Domestic loans
Financing Receivable, Nonaccrual [Line Items]
Financing Receivable, Nonaccrual, No Allowance		0
Financing Receivable, Nonaccrual		1
Nonaccrual loans		$ 1
[1] Primarily loans to real estate developers. [2] Primarily loans secured by owner-occupied real estate.

X

- Definition Amount of financing receivable on nonaccrual status with no allowance for credit loss. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 16 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=121599337&loc=SL82919258-210447 + Details Name: us-gaap_FinancingReceivableNonaccrualNoAllowance Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: instant

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X

- Definition Amount of financing receivable on nonaccrual status. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 7 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=121611835&loc=d3e5111-111524 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 16 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=121599337&loc=SL82919258-210447 + Details Name: us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: instant

X

- Definition Reflects the carrying amount of loans deemed to be questionable as to collection on which no interest is continuing to be recognized. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 7 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=121611835&loc=d3e5111-111524 + Details Name: us-gaap_LoansAndLeasesReceivableImpairedNonperformingNonaccrualOfInterest Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: instant

X

- Details Name: us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_CommercialPortfolioSegmentMember Namespace Prefix: Data Type: na Balance Type: Period Type:

X

- Details Name: us-gaap_ClassOfFinancingReceivableTypeOfBorrowerAxis=us-gaap_CommercialBorrowerMember Namespace Prefix: Data Type: na Balance Type: Period Type:

X

- Details Name: us-gaap_GeographicDistributionAxis=us-gaap_GeographicDistributionDomesticMember Namespace Prefix: Data Type: na Balance Type: Period Type:

X

- Details Name: us-gaap_GeographicDistributionAxis=us-gaap_GeographicDistributionForeignMember Namespace Prefix: Data Type: na Balance Type: Period Type:

X

- Details Name: us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_ConsumerPortfolioSegmentMember Namespace Prefix: Data Type: na Balance Type: Period Type:

X

- Details Name: us-gaap_ClassOfFinancingReceivableTypeOfBorrowerAxis=us-gaap_ConsumerBorrowerMember Namespace Prefix: Data Type: na Balance Type: Period Type:

X

- Details Name: us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_RealEstateLoanMember Namespace Prefix: Data Type: na Balance Type: Period Type:

X

- Details Name: us-gaap_EquitySecuritiesByIndustryAxis=us-gaap_RealEstateSectorMember Namespace Prefix: Data Type: na Balance Type: Period Type:

X

- Details Name: us-gaap_EquitySecuritiesByIndustryAxis=us-gaap_CommercialAndIndustrialSectorMember Namespace Prefix: Data Type: na Balance Type: Period Type:

X

- Details Name: us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_ResidentialMortgageMember Namespace Prefix: Data Type: na Balance Type: Period Type:

X

- Details Name: us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_HomeEquityLoanMember Namespace Prefix: Data Type: na Balance Type: Period Type:

X

- Details Name: us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=cma_ConsumerFinancingReceivableMember Namespace Prefix: Data Type: na Balance Type: Period Type:

X

- Details Name: cma_LoanClassificationAxis=cma_BusinessLoansMember Namespace Prefix: Data Type: na Balance Type: Period Type:

X

- Details Name: us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_FinanceLeasesPortfolioSegmentMember Namespace Prefix: Data Type: na Balance Type: Period Type:

v3.20.2

Credit Quality And Allowance For Credit Losses (Troubled Debt Restructurings By Type Of Modification) (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Troubled Debt Restructuring, Postmodification		$ 0	$ 1	$ 17	$ 13
Commitments to lend additional funds to TDR borrowers		2		2		$ 3
Business loans | Commercial borrower | Domestic loans
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Troubled Debt Restructuring, Postmodification				16	11
Business loans | Commercial mortgage | Commercial borrower | Domestic loans | Other business lines
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Troubled Debt Restructuring, Postmodification				1	1
Retail | Retail | Domestic loans
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Troubled Debt Restructuring, Postmodification		0	1	0	1
Principal Deferrals
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Troubled Debt Restructuring, Postmodification	[1]	0	0	17	12
Subsequent default during period		6	0	15	0
Principal Deferrals | Business loans | Commercial borrower | Domestic loans
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Troubled Debt Restructuring, Postmodification	[1]			16	11
Principal Deferrals | Business loans | Commercial mortgage | Commercial borrower | Domestic loans | Other business lines
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Troubled Debt Restructuring, Postmodification	[1],[2]			1	1
Principal Deferrals | Retail | Retail | Domestic loans
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Troubled Debt Restructuring, Postmodification	[1],[3]	0	0	0	0
Interest Rate Reductions
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Troubled Debt Restructuring, Postmodification		0	1	0	1
Subsequent default during period		0	0	0	0
Interest Rate Reductions | Business loans | Commercial borrower | Domestic loans
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Troubled Debt Restructuring, Postmodification				0	0
Interest Rate Reductions | Business loans | Commercial mortgage | Commercial borrower | Domestic loans | Other business lines
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Troubled Debt Restructuring, Postmodification				0	0
Interest Rate Reductions | Retail | Retail | Domestic loans
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Troubled Debt Restructuring, Postmodification		$ 0	$ 1	$ 0	$ 1
[1] Primarily represents loan balances where terms were extended by more than an insignificant time period, typically more than 180 days, at or above contractual interest rates. Also includes commercial loans restructured in bankruptcy. [2] Primarily loans secured by owner-occupied real estate. [3] Includes bankruptcy loans for which the court has discharged the borrower's obligation and the borrower has not reaffirmed the debt.

X

- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details Name: us-gaap_FinancingReceivableModificationsLineItems Namespace Prefix: us-gaap_ Data Type: xbrli:stringItemType Balance Type: na Period Type: duration

X

- Definition Amount, after troubled debt restructuring, of modified financing receivable. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 33 -URI http://asc.fasb.org/extlink&oid=121611835&loc=SL6953676-111524 + Details Name: us-gaap_FinancingReceivableModificationsPostModificationRecordedInvestment2 Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: duration

X

- Definition Amount of financing receivable modified as troubled debt restructuring within previous 12 months, with subsequent payment default. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 34 -Subparagraph (a)(2) -URI http://asc.fasb.org/extlink&oid=121611835&loc=SL6953682-111524 + Details Name: us-gaap_FinancingReceivableModificationsSubsequentDefaultRecordedInvestment1 Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: duration

X

- Definition Amount of unfunded portion of contractual agreement to lend funds to borrower for financing receivable modified as troubled debt restructuring. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 40 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=121585226&loc=d3e18794-111554 + Details Name: us-gaap_LoansAndLeasesReceivableImpairedCommitmentToLend Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: instant

X

- Details Name: us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_CommercialPortfolioSegmentMember Namespace Prefix: Data Type: na Balance Type: Period Type:

X

- Details Name: us-gaap_ClassOfFinancingReceivableTypeOfBorrowerAxis=us-gaap_CommercialBorrowerMember Namespace Prefix: Data Type: na Balance Type: Period Type:

X

- Details Name: us-gaap_GeographicDistributionAxis=us-gaap_GeographicDistributionDomesticMember Namespace Prefix: Data Type: na Balance Type: Period Type:

X

- Details Name: us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_RealEstateLoanMember Namespace Prefix: Data Type: na Balance Type: Period Type:

X

- Details Name: us-gaap_EquitySecuritiesByIndustryAxis=us-gaap_CommercialAndIndustrialSectorMember Namespace Prefix: Data Type: na Balance Type: Period Type:

X

- Details Name: us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_RetailMember Namespace Prefix: Data Type: na Balance Type: Period Type:

X

- Details Name: us-gaap_ClassOfFinancingReceivableTypeOfBorrowerAxis=us-gaap_RetailMember Namespace Prefix: Data Type: na Balance Type: Period Type:

X

- Details Name: us-gaap_LoanRestructuringModificationAxis=us-gaap_PaymentDeferralMember Namespace Prefix: Data Type: na Balance Type: Period Type:

X

- Details Name: us-gaap_LoanRestructuringModificationAxis=us-gaap_ContractualInterestRateReductionMember Namespace Prefix: Data Type: na Balance Type: Period Type:

v3.20.2

Credit Quality And Allowance For Credit Losses Foreclosed Properties (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Nonaccrual Loans [Abstract]
Foreclosed properties	$ 11	$ 11

X

- Definition Nonaccrual Loans [Abstract] + References No definition available. + Details Name: cma_NonaccrualLoansAbstract Namespace Prefix: cma_ Data Type: xbrli:stringItemType Balance Type: na Period Type: duration

X

- Definition Carrying amount as of the balance sheet date of all assets obtained in full or partial satisfaction of a debt arrangement through foreclosure proceedings or defeasance; includes real and personal property; equity interests in corporations, partnerships, and joint ventures; and beneficial interests in trusts. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 11 -URI http://asc.fasb.org/extlink&oid=121611835&loc=d3e5162-111524 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 45 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=121593590&loc=d3e4437-111522 + Details Name: us-gaap_ForeclosedAssets Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: instant

v3.20.2

Derivative And Credit-Related Financial Instruments (Narrative) (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Cash received as collateral for derivative assets	$ 216
Fair value of securities pledged as collateral for derivative assets	56
Cash posted as collateral for derivative liabilities	30
Aggregate fair value of all derivative instruments with credit-risk contingent features that were in a liability position	0
Net gain on open foreign currency positions		$ 0
Allowance for credit losses on lending-related commitments	59		$ 31
Allowance for credit losses on lending-related commitments, amount related to unused commitments to extend credit	$ 47		25
Final year of expiration for outstanding letters of credit	2028
Risk participation agreements covering standby and commercial letters of credit	$ 163		161
Standby and commercial letters of credit	3,200		3,300
Carrying value of standby and commercial letters of credit included in accrued expenses and other liabilities	34		32
Deferred fees on standby and commercial letters of credit included in accrued expenses and other liabilities	22		26
Allowance for credit losses on lending-related commitments, amount related to standby and commercial letters of credit	12		6
Notional amount of derivative credit risk participation agreements	1,100		786
Maximum estimated exposure to credit risk participation agreements assuming 100% default	$ 76		$ 20
Weighted average remaining maturity of credit risk participation agreements, in years	4 years 8 months 12 days

X

- Definition Allowance For Off Balance Sheet Credit Losses + References No definition available. + Details Name: cma_AllowanceForOffBalanceSheetCreditLosses Namespace Prefix: cma_ Data Type: xbrli:monetaryItemType Balance Type: credit Period Type: instant

X

- Definition Carrying value of standby and commercial letters of credit included in accrued expenses and other liabilities on the consolidated balance sheet. + References No definition available. + Details Name: cma_CarryingValueOfStandbyAndCommercialLettersOfCredit Namespace Prefix: cma_ Data Type: xbrli:monetaryItemType Balance Type: credit Period Type: instant

X

- Definition Carrying value of standby and commercial letters of credit included in the allowance for lending-related commitments. + References No definition available. + Details Name: cma_CarryingValueOfStandbyAndCommercialLettersOfCreditIncludedInAllowanceForCreditLossesOnLendingRelatedCommitments Namespace Prefix: cma_ Data Type: xbrli:monetaryItemType Balance Type: credit Period Type: instant

X

- Definition Carrying value of standby and commercial letters of credit included in deferred fees. + References No definition available. + Details Name: cma_CarryingValueOfStandbyAndCommercialLettersOfCreditIncludedInDeferredFees Namespace Prefix: cma_ Data Type: xbrli:monetaryItemType Balance Type: credit Period Type: instant

X

- Definition Carrying value of unused commitments to extend credit, included in the allowance for credit losses on lending-related commitments. + References No definition available. + Details Name: cma_CarryingValueOfUnusedCommitmentsToExtendCredit Namespace Prefix: cma_ Data Type: xbrli:monetaryItemType Balance Type: credit Period Type: instant

X

- Definition Cash Collateral Posted For Derivatives In Liability Position. Includes both the amount of cash offset against derivative liabilities under master netting arrangments and amounts not offset. + References No definition available. + Details Name: cma_CashCollateralPostedForDerivativesInLiabilityPosition Namespace Prefix: cma_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: instant

X

- Definition The total value of cash collateral received from counterparties to secure the fair value of derivative contracts in an unrealized gain position. Includes both the amount offset against derivative assets under master netting arrangements as well as cash collateral that has not been offset. + References No definition available. + Details Name: cma_DerivativeAssetsCashCollateral Namespace Prefix: cma_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: instant

X

- Definition Longest Expiration Year Letters Of Credit + References No definition available. + Details Name: cma_LongestExpirationYearLettersOfCredit Namespace Prefix: cma_ Data Type: xbrli:gYearItemType Balance Type: na Period Type: duration

X

- Definition Notional amount of derivative credit risk participation agreements under which the participant assumes counterparty credit exposure associated with a borrower's performance related to certain derivative contracts. + References No definition available. + Details Name: cma_NotionalAmountOfDerivativeCreditRiskParticipationAgreements Namespace Prefix: cma_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: instant

X

- Definition Total risk participations with third parties covering standby and commercial letters of credit outstanding. + References No definition available. + Details Name: cma_RiskParticipationsCoveringStandbyAndCommercialLettersOfCredit Namespace Prefix: cma_ Data Type: xbrli:monetaryItemType Balance Type: credit Period Type: instant

X

- Definition Average period covered by credit risk derivative contracts, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4K -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=121590274&loc=SL5708775-113959 + Details Name: us-gaap_AverageTermOfCreditRiskDerivatives1 Namespace Prefix: us-gaap_ Data Type: xbrli:durationItemType Balance Type: na Period Type: duration

X

- Definition Maximum potential amount of future undiscounted payments that could be required under the credit derivative, before reduction for potential recoveries under recourse or collateralization provisions. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4K -Subparagraph (b)(1) -URI http://asc.fasb.org/extlink&oid=121590274&loc=SL5708775-113959 + Details Name: us-gaap_CreditDerivativeMaximumExposureUndiscounted Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: credit Period Type: instant

X

- Definition Fair value of securities received as collateral against derivative assets. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 55 -Paragraph 12 -URI http://asc.fasb.org/extlink&oid=99393222&loc=SL20226013-175313 + Details Name: us-gaap_DerivativeAssetFairValueOfCollateral Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: credit Period Type: instant

X

- References No definition available. + Details Name: us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosureAbstract Namespace Prefix: us-gaap_ Data Type: xbrli:stringItemType Balance Type: na Period Type: duration

X

- Definition The aggregate fair value amounts of derivative instruments that contain credit-risk-related contingent features that are in a net liability position at the end of the reporting period. For nonderivative instruments that are designated and qualify as hedging instruments, the fair value amounts are the carrying value of the nonderivative hedging instrument, including the adjustment for the foreign currency transaction gain (loss) on that instrument. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4H -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=121590274&loc=SL5624258-113959 + Details Name: us-gaap_DerivativeNetLiabilityPositionAggregateFairValue Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: credit Period Type: instant

X

- Definition Amount of gain (loss) recognized in earnings in the period from the increase (decrease) in fair value of foreign currency derivatives not designated as hedging instruments. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4A -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=121590274&loc=SL5618551-113959 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4C -Subparagraph (e) -URI http://asc.fasb.org/extlink&oid=121590274&loc=SL5624171-113959 + Details Name: us-gaap_GainLossOnForeignCurrencyDerivativeInstrumentsNotDesignatedAsHedgingInstruments Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: credit Period Type: duration

X

- Definition The total amount of the contingent obligation under letters of credit outstanding as of the reporting date. + References No definition available. + Details Name: us-gaap_LettersOfCreditOutstandingAmount Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: credit Period Type: instant

v3.20.2

Derivative And Credit-Related Financial Instruments (Schedule Of Derivative Instruments) (Details) - USD ($) $ in Millions		Jun. 30, 2020	Dec. 31, 2019
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	[1]	$ 33,754	$ 30,134
Fair Value of Gross Derivative Assets		935	317
Fair Value of Gross Derivative Liabilities		351	141
Derivative assets, Netting adjustment - Offsetting derivative liabilities		(54)	(63)
Derivative liabilities, Netting adjustment - Offsetting derivative assets		(54)	(63)
Derivative assets, Netting adjustment - Cash collateral received		(214)	(11)
Derivative liabilities, Netting adjustment, Cash collateral posted		(28)	(12)
Net derivative assets included in the consolidated balance sheets	[2]	667	243
Net derivative liabilities included in the consolidated balance sheets	[2]	269	66
Derivative asset, securities pledged as collateral		0	0
Derivative liability, securities pledged as collateral		(53)	(21)
Net derivative assets after deducting amounts not offset in the consolidated balance sheets		667	243
Net derivative liabilities after deducting amounts not offset in the consolidated balance sheets		216	45
Credit valuation adjustments for counterparty credit risk		25	9
Risk management purposes
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	[1]	8,530	8,205
Fair Value of Gross Derivative Assets		1	0
Fair Value of Gross Derivative Liabilities		2	2
Risk management purposes | Derivatives designated as hedging instruments | Swaps - fair value - receive fixed/pay floating | Interest rate swap
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	[1]	2,650	4,550
Fair Value of Gross Derivative Assets		0	0
Fair Value of Gross Derivative Liabilities		0	0
Risk management purposes | Derivatives designated as hedging instruments | Swaps - cash flow - receive fixed/pay floating rate | Interest rate swap
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	[1]	5,550	3,325
Fair Value of Gross Derivative Assets		0	0
Fair Value of Gross Derivative Liabilities		0	0
Risk management purposes | Derivatives used as economic hedges | Foreign exchange spot, forwards and swaps
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	[1]	330	330
Fair Value of Gross Derivative Assets		1	0
Fair Value of Gross Derivative Liabilities		2	2
Customer-initiated and other activities
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	[1]	25,224	21,929
Fair Value of Gross Derivative Assets		934	317
Fair Value of Gross Derivative Liabilities		349	139
Customer-initiated and other activities | Interest rate contracts
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	[1]	21,241	17,827
Fair Value of Gross Derivative Assets		649	211
Fair Value of Gross Derivative Liabilities		73	39
Customer-initiated and other activities | Interest rate caps and floors written
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	[1]	601	671
Fair Value of Gross Derivative Assets		0	0
Fair Value of Gross Derivative Liabilities		1	0
Customer-initiated and other activities | Interest rate caps and floors purchased
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	[1]	601	671
Fair Value of Gross Derivative Assets		1	0
Fair Value of Gross Derivative Liabilities		0	0
Customer-initiated and other activities | Interest rate swap
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	[1]	20,039	16,485
Fair Value of Gross Derivative Assets		648	211
Fair Value of Gross Derivative Liabilities		72	39
Customer-initiated and other activities | Energy contracts
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	[1]	3,015	3,089
Fair Value of Gross Derivative Assets		271	96
Fair Value of Gross Derivative Liabilities		263	92
Customer-initiated and other activities | Energy caps and floors written
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	[1]	439	477
Fair Value of Gross Derivative Assets		0	0
Fair Value of Gross Derivative Liabilities		46	23
Customer-initiated and other activities | Energy caps and floors purchased
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	[1]	439	477
Fair Value of Gross Derivative Assets		46	23
Fair Value of Gross Derivative Liabilities		0	0
Customer-initiated and other activities | Energy swaps
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	[1]	2,137	2,135
Fair Value of Gross Derivative Assets		225	73
Fair Value of Gross Derivative Liabilities		217	69
Customer-initiated and other activities | Foreign exchange spot, options and swaps
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	[1]	968	1,013
Fair Value of Gross Derivative Assets		14	10
Fair Value of Gross Derivative Liabilities		$ 13	$ 8
[1] Notional or contractual amounts, which represent the extent of involvement in the derivatives market, are used to determine the contractual cash flows required in accordance with the terms of the agreement. These amounts are typically not exchanged, significantly exceed amounts subject to credit or market risk and are not reflected in the Consolidated Balance Sheets. [2] Net derivative assets are included in accrued income and other assets and net derivative liabilities are included in accrued expenses and other liabilities on the Consolidated Balance Sheets. Included in the fair value of net derivative assets and net derivative liabilities are credit valuation adjustments reflecting counterparty credit risk and credit risk of the Corporation. The fair value of net derivative assets included credit valuation adjustments for counterparty credit risk of $25 million and $9 million at June 30, 2020 and December 31, 2019, respectively.

X

- Definition Amount of obligation to return cash collateral under master netting arrangements offset against derivative assets. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 50 -Paragraph 3 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 45 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=117331979&loc=d3e41228-113958 + Details Name: us-gaap_DerivativeAssetCollateralObligationToReturnCashOffset Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: credit Period Type: instant

X

- Definition Fair value of liability associated with financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4B -Subparagraph (a),(c) -URI http://asc.fasb.org/extlink&oid=121590274&loc=SL5624163-113959 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 55 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=99393222&loc=SL20226003-175313 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 50 -Paragraph 3 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312 + Details Name: us-gaap_DerivativeAssetFairValueGrossLiability Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: credit Period Type: instant

X

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v3.20.2

Derivative And Credit-Related Financial Instruments Derivative and Credit-Related Financial Instruments (Schedule of the Effects of Fair Value Hedging on the Consolidated Statements of Comprehensive Income (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Total interest on medium- and long-term debt	[1]	$ 19	$ 51	$ 59	$ 102
Swaps - fair value - receive fixed/pay floating | Risk management purposes | Interest rate swap
Interest rate contract: Hedge items interest expense		28	26	58	52
Interest rate contracts: Derivatives designated as hedging instruments net interest income		$ (12)	$ 0	$ (18)	$ 1
[1] Includes the effects of hedging.

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v3.20.2

Derivative And Credit-Related Financial Instruments (Schedule Of Weighted Average Maturity And Interest Rates On Risk Management Cash Flow Swaps) (Details) - USD ($) $ in Millions		6 Months Ended
		Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Derivative, Notional Amount	[1]	$ 33,754		$ 30,134
Risk management purposes
Derivative, Notional Amount	[1]	8,530		8,205
Variable rate loans | Swaps - cash flow - receive fixed/pay floating rate | Risk management purposes | Cash flow swap
Derivative, Notional Amount		$ 5,550		$ 4,550
Weighted Average Remaining Maturity		2 years 9 months 18 days	3 years
Derivative, Average Fixed Interest Rate		1.87%		1.94%
Derivative, Average Variable Interest Rate	[2]	0.17%		1.71%
[1] Notional or contractual amounts, which represent the extent of involvement in the derivatives market, are used to determine the contractual cash flows required in accordance with the terms of the agreement. These amounts are typically not exchanged, significantly exceed amounts subject to credit or market risk and are not reflected in the Consolidated Balance Sheets. [2] Variable rates paid on receive fixed swaps designated as cash flow hedges are based on one-month LIBOR rates in effect at June 30, 2020 and December 31, 2019.

X

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X

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v3.20.2

Derivative And Credit-Related Financial Instruments Derivative And Credit-Related Financial Instruments (Schedule Of Weighted Average Maturity And Interest Rates On Risk Management Fair Value Swaps) (Details) - USD ($) $ in Millions		6 Months Ended	12 Months Ended
		Jun. 30, 2020	Dec. 31, 2019
Derivative, Notional Amount	[1]	$ 33,754	$ 30,134
Risk management purposes
Derivative, Notional Amount	[1]	8,530	8,205
Interest rate swap | Fair Value Hedging [Member] | Risk management purposes | Long-term Debt [Member]
Derivative, Notional Amount		2,650	3,325
Carryingvalueofhedgeditem	[2]	$ 2,971	$ 3,469
Weighted Average Remaining Maturity		5 years 1 month 6 days	4 years 7 months 6 days
Derivative, Average Fixed Interest Rate		3.68%	3.44%
Derivative, Average Variable Interest Rate	[3]	1.54%	2.80%
[1] Notional or contractual amounts, which represent the extent of involvement in the derivatives market, are used to determine the contractual cash flows required in accordance with the terms of the agreement. These amounts are typically not exchanged, significantly exceed amounts subject to credit or market risk and are not reflected in the Consolidated Balance Sheets. [2] Included $322 million and $146 million of cumulative hedging adjustments at June 30, 2020 and December 31, 2019, respectively, which included $6 million and $7 million, respectively, of hedging adjustment on a discontinued hedging relationship. [3] Variable rates paid on receive fixed swaps designated as fair value hedges are based on one- and six-month LIBOR rates in effect at June 30, 2020 and December 31, 2019.

X

- Definition Carrying value of hedged debt + References No definition available. + Details Name: cma_Carryingvalueofhedgeditem Namespace Prefix: cma_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: instant

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X

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- Details Name: us-gaap_BalanceSheetLocationAxis=us-gaap_LongTermDebtMember Namespace Prefix: Data Type: na Balance Type: Period Type:

v3.20.2

Derivative And Credit-Related Financial Instruments (Schedule Of Net Gains Recognized In Income On Customer-Initiated Derivatives) (Details) - Customer-initiated and other activities - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Derivative Instruments, Gain (Loss) [Line Items]
Net derivative gain recognized in income	$ 19	$ 19	$ 39	$ 37
Interest rate contracts | Other noninterest income
Derivative Instruments, Gain (Loss) [Line Items]
Net derivative gain recognized in income	8	6	16	12
Energy contracts | Other noninterest income
Derivative Instruments, Gain (Loss) [Line Items]
Net derivative gain recognized in income	2	2	3	3
Foreign exchange contracts | Foreign exchange income
Derivative Instruments, Gain (Loss) [Line Items]
Net derivative gain recognized in income	$ 9	$ 11	$ 20	$ 22

X

- Definition Amount of increase (decrease) in the fair value of derivatives recognized in the income statement. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4A -Subparagraph (b)(1) -URI http://asc.fasb.org/extlink&oid=121590274&loc=SL5618551-113959 + Details Name: us-gaap_DerivativeGainLossOnDerivativeNet Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: credit Period Type: duration

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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details Name: us-gaap_DerivativeInstrumentsGainLossLineItems Namespace Prefix: us-gaap_ Data Type: xbrli:stringItemType Balance Type: na Period Type: duration

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- Details Name: cma_DerivativePurposeAxis=cma_CustomerInitiatedAndOtherActivitiesDerivativesMember Namespace Prefix: Data Type: na Balance Type: Period Type:

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- Details Name: us-gaap_DerivativeInstrumentRiskAxis=us-gaap_InterestRateContractMember Namespace Prefix: Data Type: na Balance Type: Period Type:

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- Details Name: us-gaap_IncomeStatementLocationAxis=us-gaap_OtherIncomeMember Namespace Prefix: Data Type: na Balance Type: Period Type:

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- Details Name: us-gaap_DerivativeInstrumentRiskAxis=us-gaap_EnergyRelatedDerivativeMember Namespace Prefix: Data Type: na Balance Type: Period Type:

X

- Details Name: us-gaap_DerivativeInstrumentRiskAxis=us-gaap_ForeignExchangeContractMember Namespace Prefix: Data Type: na Balance Type: Period Type:

X

- Details Name: us-gaap_IncomeStatementLocationAxis=us-gaap_ForeignCurrencyGainLossMember Namespace Prefix: Data Type: na Balance Type: Period Type:

v3.20.2

Derivative And Credit-Related Financial Instruments (Schedule Of Financial Instruments With Off-Balance Sheet Credit Risk) (Details) - Maximum - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Unused Commitments to Extend Credit
Loss contingency, estimate of possible loss	$ 25,863	$ 26,861
Commercial And Other | Unused Commitments to Extend Credit
Loss contingency, estimate of possible loss	22,588	23,681
Bankcard, Revolving Check Credit And Home Equity Loan Commitments | Unused Commitments to Extend Credit
Loss contingency, estimate of possible loss	3,275	3,180
Standby Letters Of Credit
Loss contingency, estimate of possible loss	3,185	3,320
Commercial Letters Of Credit
Loss contingency, estimate of possible loss	$ 19	$ 18

X

- Definition Reflects the estimated amount of loss from the specified contingency as of the balance sheet date. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 450 -SubTopic 20 -Section 50 -Paragraph 4 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=121557415&loc=d3e14435-108349 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 450 -SubTopic 20 -Section 50 -Paragraph 9 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=121557415&loc=d3e14557-108349 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 460 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=121555522&loc=d3e12021-110248 + Details Name: us-gaap_LossContingencyEstimateOfPossibleLoss Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: instant

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- Details Name: srt_RangeAxis=srt_MaximumMember Namespace Prefix: Data Type: na Balance Type: Period Type:

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- Details Name: us-gaap_FinancialInstrumentAxis=us-gaap_CommitmentsToExtendCreditMember Namespace Prefix: Data Type: na Balance Type: Period Type:

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- Details Name: cma_CreditRelatedFinancialInstrumentsAxis=cma_CommercialAndOtherMember Namespace Prefix: Data Type: na Balance Type: Period Type:

X

- Details Name: cma_CreditRelatedFinancialInstrumentsAxis=cma_BankcardHomeEquityAndOtherMember Namespace Prefix: Data Type: na Balance Type: Period Type:

X

- Details Name: cma_CreditRelatedFinancialInstrumentsAxis=us-gaap_StandbyLettersOfCreditMember Namespace Prefix: Data Type: na Balance Type: Period Type:

X

- Details Name: cma_CreditRelatedFinancialInstrumentsAxis=us-gaap_LetterOfCreditMember Namespace Prefix: Data Type: na Balance Type: Period Type:

v3.20.2

Derivative And Credit-Related Financial Instruments (Summary Of Internally Classified Watch List Letters Of Credit) (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Total criticized standby and commercial letters of credit	$ 83	$ 44
As a percentage of total outstanding standby and commercial letters of credit	2.60%	1.30%

X

- Definition Total internally classified watch list standby and commercial letters of credit (generally consistent with regulatory defined special mention, substandard and doubtful). + References No definition available. + Details Name: cma_TotalInternallyClassifiedWatchListLettersOfCredit Namespace Prefix: cma_ Data Type: xbrli:monetaryItemType Balance Type: credit Period Type: instant

X

- Definition Total internally classified watch list standby and commercial letters of credit as a percentage of total standby and commercial letters of credit. + References No definition available. + Details Name: cma_WatchListLettersOfCreditAsPercentageOfTotalLettersOfCredit Namespace Prefix: cma_ Data Type: num:percentItemType Balance Type: na Period Type: instant

X

- References No definition available. + Details Name: us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosureAbstract Namespace Prefix: us-gaap_ Data Type: xbrli:stringItemType Balance Type: na Period Type: duration

v3.20.2

Variable Interest Entities (VIEs) (Narrative) (Details) - USD ($) $ in Millions		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2020	Jun. 30, 2019
Variable Interest Entity
Unfunded commitments to fund tax credit entities	$ 173
Amount of financial or other support not contractually required provided by the Corporation to VIEs		$ 0	$ 0
Low Income Housing Tax Credit Entities
Variable Interest Entity
Exposure to loss as a result of involvement with VIEs	451	451
Other Tax Credit Entities [Member]
Variable Interest Entity
Exposure to loss as a result of involvement with VIEs	$ 10	$ 10

X

- Definition The amount of expense between the reporting entity and the Variable Interest Entity (VIE). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 810 -SubTopic 10 -Section 50 -Paragraph 6 -Subparagraph d -URI http://asc.fasb.org/extlink&oid=121559654&loc=d3e5747-111685 + Details Name: us-gaap_VariableInterestEntityActivityBetweenVIEAndEntityExpense Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: duration

X

- Definition The reporting entity's maximum amount of exposure to loss as a result of its involvement with the Variable Interest Entity (VIE). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 810 -SubTopic 10 -Section 50 -Paragraph 6 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=121559654&loc=d3e5747-111685 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 810 -SubTopic 10 -Section 50 -Paragraph 4 -Subparagraph b -URI http://asc.fasb.org/extlink&oid=121559654&loc=d3e5728-111685 + Details Name: us-gaap_VariableInterestEntityEntityMaximumLossExposureAmount Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: credit Period Type: instant

X

- Definition The amount of financial or other support the reporting entity has provided (explicitly or implicitly) to the Variable Interest Entity (VIE) that it was not previously contractually required to provide or that the reporting entity intends to provide, including, for example, situations in which the reporting entity assisted the VIE in obtaining another type of support. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 810 -SubTopic 10 -Section 50 -Paragraph 5A -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=121559654&loc=SL6759159-111685 + Details Name: us-gaap_VariableInterestEntityFinancialOrOtherSupportAmount Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: duration

X

- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details Name: us-gaap_VariableInterestEntityLineItems Namespace Prefix: us-gaap_ Data Type: xbrli:stringItemType Balance Type: na Period Type: duration

X

- Details Name: us-gaap_InvestmentsByConsolidatedAndNonconsolidatedEntitiesAxis=cma_LowIncomeHousingTaxCreditEntitiesMember Namespace Prefix: Data Type: na Balance Type: Period Type:

X

- Details Name: us-gaap_InvestmentsByConsolidatedAndNonconsolidatedEntitiesAxis=cma_OtherTaxCreditEntitiesMember Namespace Prefix: Data Type: na Balance Type: Period Type:

v3.20.2

Variable Interest Entities (VIEs) (Impact Of VIEs On The Consolidated Statements Of Comprehensive Income) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Variable Interest Entity
Other noninterest income	$ 35	$ 22	$ 55	$ 47
Provision for income taxes	27	87	6	172
Variable Interest Entity
Variable Interest Entity
Other noninterest income	0	0	0	1
Provision for income taxes	(2)	(2)	(5)	(5)
Low income housing tax credits | Variable Interest Entity
Variable Interest Entity
Provision for income taxes, amortization of LIHTC investments	17	17	34	32
Provision for income taxes, affordable housing tax credits and other tax benefits	(16)	(15)	(32)	(30)
Other tax benefits related to tax credit entities | Variable Interest Entity
Variable Interest Entity
Provision for income taxes, affordable housing tax credits and other tax benefits	$ (3)	$ (4)	$ (7)	$ (7)

X

- Definition Amount of affordable housing tax credits and other tax benefits recognized. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 323 -SubTopic 740 -Section 50 -Paragraph 2 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=116633289&loc=SL49122993-202985 + Details Name: us-gaap_AffordableHousingTaxCreditsAndOtherTaxBenefitsAmount Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: credit Period Type: duration

X

- Definition Amount of amortization expense of investment in qualified affordable housing projects. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 323 -SubTopic 740 -Section 50 -Paragraph 2 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=116633289&loc=SL49122993-202985 + Details Name: us-gaap_AmortizationMethodQualifiedAffordableHousingProjectInvestmentsAmortization Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: duration

X

- Definition Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SAB TOPIC 6.I.7) -URI http://asc.fasb.org/extlink&oid=116825942&loc=d3e330036-122817 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 10 -URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32672-109319 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 280 -SubTopic 10 -Section 50 -Paragraph 22 -Subparagraph (h) -URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8736-108599 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.4-08(h)) -URI http://asc.fasb.org/extlink&oid=120395691&loc=d3e23780-122690 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 250 -SubTopic 10 -Section 50 -Paragraph 9 -URI http://asc.fasb.org/extlink&oid=109234566&loc=d3e22663-107794 Reference 6: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 20 -Section 45 -Paragraph 2 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=120385591&loc=d3e38679-109324 Reference 7: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 220 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-04(9)) -URI http://asc.fasb.org/extlink&oid=120400993&loc=SL114874131-224263 Reference 8: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 250 -SubTopic 10 -Section 50 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=109234566&loc=d3e22658-107794 + Details Name: us-gaap_IncomeTaxExpenseBenefit Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: duration

X

- Definition Amount of revenue earned, classified as other, excluding interest income. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-03(1)(e)) -URI http://asc.fasb.org/extlink&oid=120395209&loc=SL114868656-224227 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 220 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-04(13)) -URI http://asc.fasb.org/extlink&oid=120399700&loc=SL114874048-224260 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 220 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-04(4)) -URI http://asc.fasb.org/extlink&oid=120400993&loc=SL114874131-224263 + Details Name: us-gaap_NoninterestIncomeOtherOperatingIncome Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: credit Period Type: duration

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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details Name: us-gaap_VariableInterestEntityLineItems Namespace Prefix: us-gaap_ Data Type: xbrli:stringItemType Balance Type: na Period Type: duration

X

- Details Name: us-gaap_InvestmentsByConsolidatedAndNonconsolidatedEntitiesAxis=us-gaap_VariableInterestEntityNotPrimaryBeneficiaryMember Namespace Prefix: Data Type: na Balance Type: Period Type:

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- Details Name: cma_TaxCreditsandBenefitsRelatedToTaxCreditEntitiesAxis=cma_LowIncomeHousingTaxCreditsMember Namespace Prefix: Data Type: na Balance Type: Period Type:

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- Details Name: cma_TaxCreditsandBenefitsRelatedToTaxCreditEntitiesAxis=cma_OtherTaxBenefitsRelatedToTaxCreditEntitiesMember Namespace Prefix: Data Type: na Balance Type: Period Type:

v3.20.2

Medium- And Long-Term Debt (Narrative) (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Federal Home Loan Bank, Advances, Weighted Average Interest Rate	0.31%
Real estate-related loans securing FHLB advances	$ 18,300
Pledged to the FHLB as collateral for potential future borrowings	5,200
Short-term Federal Home Loan Bank Advances	750
Long-term Federal Home Loan Bank Advances	3,600
Potential future borrowings	10,100
Unamortized debt issuance cost	$ 11	$ 12
Subsidiaries | Floating-rate based on FHLB auction rate due 2026
Debt Instrument [Line Items]
Weighted-average interest rate	0.27%
Subsidiaries | Floating-rate based on FHLB auction rate due 2028
Debt Instrument [Line Items]
Weighted-average interest rate	0.35%

X

- Definition Short-term Federal Home Loan Bank Advances + References No definition available. + Details Name: cma_ShorttermFederalHomeLoanBankAdvances Namespace Prefix: cma_ Data Type: xbrli:monetaryItemType Balance Type: credit Period Type: instant

X

- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details Name: us-gaap_DebtInstrumentLineItems Namespace Prefix: us-gaap_ Data Type: xbrli:stringItemType Balance Type: na Period Type: duration

X

- Definition Including both current and noncurrent portions, Federal Home Loan Bank borrowings initially due beyond one year or beyond the normal operating cycle if longer. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03.16) -URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 470 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=75038535&loc=d3e64702-112823 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 470 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6479118&loc=d3e64650-112822 + Details Name: us-gaap_FederalHomeLoanBankAdvancesLongTerm Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: credit Period Type: instant

X

- Definition Weighted average interest rate on advances made and reported by Federal Home Loan Bank (FHLBank). + References No definition available. + Details Name: us-gaap_FederalHomeLoanBankAdvancesWeightedAverageInterestRate Namespace Prefix: us-gaap_ Data Type: num:percentItemType Balance Type: na Period Type: instant

X

- Definition The fair value as of the balance sheet date of financial instruments and other positions owned by the entity and pledged to counterparties as collateral, including: (1) mortgages, mortgage-backed and asset backed securities; (2) US government and agency obligations; (3) state and municipal government obligations; (4) other sovereign government debt; (5) corporate obligations; (6) corporate equities; (7) principal investments; (8) derivative contracts; and (9) physical commodities. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 860 -SubTopic 30 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=66007379&loc=d3e113888-111728 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 860 -SubTopic 30 -Section 50 -Paragraph 1A -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=109249958&loc=SL6224234-111729 + Details Name: us-gaap_FinancialInstrumentsOwnedAndPledgedAsCollateralAtFairValue Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: instant

X

- Definition Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.19(b),22(b)) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 + Details Name: us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: credit Period Type: instant

X

- Definition Weighted average interest rate of long-term debt outstanding calculated at point in time. + References No definition available. + Details Name: us-gaap_LongtermDebtWeightedAverageInterestRate Namespace Prefix: us-gaap_ Data Type: num:percentItemType Balance Type: na Period Type: instant

X

- Definition The carrying amount, as of the date of the latest financial statement presented, of loans receivable which are owned but transferred to serve as collateral for the payment of FHLB debt obligations, and for which the transferee is not permitted to sell or re-pledge them to an unrelated party. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 860 -SubTopic 30 -Section 50 -Paragraph 1A -Subparagraph (b)(1)(i) -URI http://asc.fasb.org/extlink&oid=109249958&loc=SL6224234-111729 + Details Name: us-gaap_PledgedFinancialInstrumentsNotSeparatelyReportedLoansReceivablePledgedForFederalHomeLoanBankDebt Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: instant

X

- Definition The remaining balance of debt issuance expenses that were capitalized and are being amortized against income over the lives of the respective bond issues. This does not include the amounts capitalized as part of the cost of the utility plant or asset. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.17) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 + Details Name: us-gaap_UnamortizedDebtIssuanceExpense Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: instant

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- Details Name: srt_ConsolidatedEntitiesAxis=srt_SubsidiariesMember Namespace Prefix: Data Type: na Balance Type: Period Type:

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- Details Name: us-gaap_DebtInstrumentAxis=cma_FloatingRateBasedonFHLBAuctionDue2026Member Namespace Prefix: Data Type: na Balance Type: Period Type:

X

- Details Name: us-gaap_DebtInstrumentAxis=cma_FloatingratebasedonFHLBauctionratedue2028Member Namespace Prefix: Data Type: na Balance Type: Period Type:

v3.20.2

Medium- And Long-Term Debt (Schedule Of Medium- And Long-Term Debt) (Details) - USD ($) $ in Millions		6 Months Ended
		Jun. 30, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Long-term Federal Home Loan Bank Advances		$ 3,600
Total medium- and long-term debt		6,521	$ 7,269
Parent Company
Debt Instrument [Line Items]
Medium-term notes		1,564	1,471
Total medium- and long-term debt		1,848	1,735
Subsidiaries
Debt Instrument [Line Items]
Subordinated notes		596	562
Medium-term notes		527	1,172
Long-term Federal Home Loan Bank Advances		3,550	3,800
Total medium- and long-term debt		4,673	5,534
3.80% subordinated notes due 2026 | Parent Company
Debt Instrument [Line Items]
Subordinated notes	[1]	$ 284	264
Stated interest rate		3.80%
Maturity year		2026
3.70% Notes Due 2023 | Parent Company
Debt Instrument [Line Items]
Medium-term notes	[1]	$ 917	884
Stated interest rate		3.70%
Maturity year		2023
4.00% Notes Due 2029 | Parent Company
Debt Instrument [Line Items]
Medium-term notes	[1]	$ 647	587
Stated interest rate		4.00%
Maturity year		2029
4.00% subordinated notes due 2025 | Subsidiaries
Debt Instrument [Line Items]
Subordinated notes	[1]	$ 383	360
Stated interest rate		4.00%
Maturity year		2025
7.875% subordinated notes due 2026 | Subsidiaries
Debt Instrument [Line Items]
Subordinated notes	[1]	$ 213	202
Stated interest rate		7.875%
Maturity year		2026
2.50% notes due 2020 | Subsidiaries
Debt Instrument [Line Items]
Medium-term notes	[1]	$ 0	674
Stated interest rate		2.50%
Maturity year		2020
2.50% notes due 2024 | Subsidiaries
Debt Instrument [Line Items]
Medium-term notes	[1]	$ 527	498
Stated interest rate		2.50%
Maturity year		2024
Floating-rate based on FHLB auction rate due 2026 | Subsidiaries
Debt Instrument [Line Items]
Maturity year		2026
Weighted-average interest rate		0.27%
Floating-rate based on FHLB auction rate due 2026 | Subsidiaries
Debt Instrument [Line Items]
Long-term Federal Home Loan Bank Advances		$ 2,800	2,800
Floating-rate based on FHLB auction rate due 2028 | Subsidiaries
Debt Instrument [Line Items]
Maturity year		2028
Weighted-average interest rate		0.35%
Floating-rate based on FHLB auction rate due 2028 | Subsidiaries
Debt Instrument [Line Items]
Long-term Federal Home Loan Bank Advances		$ 750	$ 1,000
[1] The fixed interest rates on these notes have been swapped to a variable rate and designated in a hedging relationship. Accordingly, carrying value has been adjusted to reflect the change in the fair value of the debt as a result of changes in the benchmark rate.

X

- Definition Debt Instrument, Maturity Year + References No definition available. + Details Name: cma_DebtInstrumentMaturityYear Namespace Prefix: cma_ Data Type: xbrli:gYearItemType Balance Type: na Period Type: duration

X

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v3.20.2

Accumulated Other Comprehensive Income (Loss) (Schedule Of Accumulated Other Comprehensive Loss) (Details) - USD ($) $ in Millions		6 Months Ended
		Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Investment securities, Balance at beginning of period, net of tax		$ 65	$ (138)
Investment securities, Net unrealized holding gains arising during the period		286	229
Investment securities, Less: Provision for income taxes		68	54
Investment securities, Net unrealized holding gains arising during the period, net of tax		218	175
Investment securities, Net realized losses gains included in net securities losses		0	(8)
Investment securities, Less: Benefit for income taxes		0	(2)
Investment Securities, Reclassification adjustment for net securities losses included in net income, net of tax		0	(6)
Investment securities, Change in net unrealized gains on investment securities, net of tax		218	181
Investment securities, Balance at end of period, net of tax		283	43
Cash flow hedges, Balance at beginning of period, net of tax		34	0
Cash flow hedge: Net gains arising during the period		233	51
Cash flow hedges, Less: Provision for income tax		56	12
Change in net cash flow hedge gains arising during the period, net of tax		177	39
Net cash flow hedge gains (losses) included in interest and fees on loans		22	(1)
Cash flow hedges, Less: Provision for income tax		7	0
Cash flow hedges, reclassification adjustment for net cash flow hedge gains (losses) included in net income, net of tax		15	(1)
Cash flows hedges, Change in net gain on cash flow hedges		162	40
Cash flow hedges, Balance at end of period, net of tax	[1]	196	40
Benefit plans, Balance at beginning of period, net of tax		(334)	(471)
Benefit plans, Amortization of actuarial net loss		31	21
Benefit plans, Amortization of prior service credit		(14)	(13)
Benefit plans, Amounts recognized in other noninterest expenses		17	8
Benefit plans, Less: Provision for income taxes		4	2
Benefit plans, Change in defined benefit pension and other postretirement plans adjustment, net of tax		13	6
Benefit plans, Balance at end of period, net of tax		(321)	(465)
Total accumulated other comprehensive income (loss) at end of period, net of tax		$ 158	$ (382)	$ (235)
[1] The Corporation expects to reclassify $73 million of net gains, net of tax, from accumulated other comprehensive income to earnings over the next twelve months if interest yield curves and notional amounts remain at June 30, 2020 levels.

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- Definition Amount before tax of increase (decrease) in accumulated gain (loss) from derivative instruments designated and qualifying as the effective portion of cash flow hedges and an entity's share of an equity investee's increase (decrease) in deferred hedging gain (loss). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 11 -URI http://asc.fasb.org/extlink&oid=121641772&loc=d3e637-108580 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 30 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=121558989&loc=d3e80720-113993 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 10A -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=121641772&loc=SL7669646-108580 + Details Name: us-gaap_OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodBeforeTax Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: credit Period Type: duration

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- Definition Amount, before adjustment, of tax expense (benefit) for unrealized holding gain (loss) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). Excludes tax expense (benefit) for unrealized gain (loss) on investment in debt security measured at amortized cost (held-to-maturity) from transfer to available-for-sale. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 12 -URI http://asc.fasb.org/extlink&oid=121641772&loc=d3e640-108580 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 10A -Subparagraph (f) -URI http://asc.fasb.org/extlink&oid=121641772&loc=SL7669646-108580 + Details Name: us-gaap_OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodTax Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: duration

v3.20.2

Net Income Per Common Share (Narrative) (Details) - USD ($)	3 Months Ended	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2020	Jun. 30, 2019
Earnings Per Share [Abstract]
Issuance of preferred stock	$ 395,000,000	$ 395,000,000	$ 0
Depositary Shares, Issued	400,000	400,000
Preferred Stock, Dividend Rate, Percentage		5.625%
Preferred Stock, Liquidation Preference, Value	$ 100,000	$ 100,000
Preferred Stock, Liquidation Preference Per Share	$ 1,000	$ 1,000
Proceeds from Issuance of Preferred Stock, Preference Stock, and Warrants		$ 400,000,000

X

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v3.20.2

Net Income Per Common Share (Basic And Diluted Net Income Per Share) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Earnings Per Share [Abstract]
Net (loss) income	$ 113	$ 298	$ 48	$ 637
Income allocated to participating securities	1	1	1	3
Net (loss) income attributable to common shares	$ 112	$ 297	$ 47	$ 634
Basic average shares	139.0	152.0	140.0	155.0
Basic net (loss) income per common share	$ 0.81	$ 1.95	$ 0.34	$ 4.10
Basic average shares	139.0	152.0	140.0	155.0
Net effect of the assumed exercise of stock options	0.0	1.0	1.0	1.0
Diluted average shares	139.0	153.0	141.0	156.0
Diluted net (loss) income per common share	$ 0.80	$ 1.94	$ 0.34	$ 4.06

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v3.20.2

Net Income Per Common Share (Ant-Dilutive Schedule) (Details) - $ / shares	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Stock awards excluded because exercise prices were greater than average market price of shares	2,056,133	470,162	1,633,078	446,610
Minimum | Share-based Payment Arrangement, Option
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Net Income, Per Outstanding Unit, Amount	$ 39.10	$ 79.01	$ 39.10	$ 79.01
Maximum | Share-based Payment Arrangement, Option
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Net Income, Per Outstanding Unit, Amount	$ 95.25	$ 95.25	$ 95.25	$ 95.25

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v3.20.2

Employee Benefit Plans (Net Periodic Defined Benefit Cost) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Defined Benefit Plan Disclosure [Line Items]
Net periodic defined benefit (credit) cost			$ (13)	$ (14)
Qualified Defined Benefit Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Total other components of net benefit (credit) cost	$ 17	$ 17	33	35
Net periodic defined benefit (credit) cost	(9)	(10)	(17)	(20)
Qualified Defined Benefit Pension Plan | Component recognized in salaries and benefits expense
Defined Benefit Plan Disclosure [Line Items]
Service cost	8	7	16	15
Qualified Defined Benefit Pension Plan | Component recognized in noninterest expenses
Defined Benefit Plan Disclosure [Line Items]
Interest Cost	17	20	35	40
Expected return on plan assets	(42)	(41)	(85)	(83)
Amortization of prior service credit	(5)	(4)	(10)	(9)
Defined Benefit Plan, Amortization of Gain (Loss)	13	8	27	17
Non-Qualified Defined Benefit Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Total other components of net benefit (credit) cost	2	2	4	4
Net periodic defined benefit (credit) cost	2	3	5	6
Non-Qualified Defined Benefit Pension Plan | Component recognized in salaries and benefits expense
Defined Benefit Plan Disclosure [Line Items]
Service cost	0	1	1	2
Non-Qualified Defined Benefit Pension Plan | Component recognized in noninterest expenses
Defined Benefit Plan Disclosure [Line Items]
Interest Cost	2	2	4	4
Amortization of prior service credit	(2)	(2)	(4)	(4)
Defined Benefit Plan, Amortization of Gain (Loss)	2	(2)	4	(4)
Postretirement Benefit Plan
Defined Benefit Plan Disclosure [Line Items]
Net periodic defined benefit (credit) cost	(1)	0	(1)	0
Postretirement Benefit Plan | Component recognized in noninterest expenses
Defined Benefit Plan Disclosure [Line Items]
Interest Cost	0	0	0	1
Expected return on plan assets	$ (1)	$ 0	$ (1)	$ (1)

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- Definition Amount of prior service cost (credit) recognized in net periodic benefit cost (credit) of defined benefit plan. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 55 -Paragraph 17 -URI http://asc.fasb.org/extlink&oid=118257860&loc=d3e4179-114921 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (h)(5) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 45 -Paragraph 3A -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=109237824&loc=SL108413299-114919 Reference 4: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 55 -Paragraph 18 -URI http://asc.fasb.org/extlink&oid=118257860&loc=d3e4587-114921 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 6 -Subparagraph (a)(5) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e2709-114920 + Details Name: us-gaap_DefinedBenefitPlanAmortizationOfPriorServiceCostCredit Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: duration

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- Definition Amount of expected return (loss) recognized in net periodic benefit (cost) credit, calculated based on expected long-term rate of return and market-related value of plan assets of defined benefit plan. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 55 -Paragraph 17 -URI http://asc.fasb.org/extlink&oid=118257860&loc=d3e4179-114921 Reference 2: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 55 -Paragraph 18 -URI http://asc.fasb.org/extlink&oid=118257860&loc=d3e4587-114921 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (h)(3) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 45 -Paragraph 3A -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=109237824&loc=SL108413299-114919 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 6 -Subparagraph (a)(3) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e2709-114920 + Details Name: us-gaap_DefinedBenefitPlanExpectedReturnOnPlanAssets Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: credit Period Type: duration

X

- Definition Amount of cost recognized for passage of time related to defined benefit plan. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (h)(2) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 45 -Paragraph 3A -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=109237824&loc=SL108413299-114919 Reference 3: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 55 -Paragraph 17 -URI http://asc.fasb.org/extlink&oid=118257860&loc=d3e4179-114921 Reference 4: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 55 -Paragraph 18 -URI http://asc.fasb.org/extlink&oid=118257860&loc=d3e4587-114921 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (a)(2) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 Reference 6: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 6 -Subparagraph (a)(2) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e2709-114920 + Details Name: us-gaap_DefinedBenefitPlanInterestCost Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: duration

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- Definition Amount of net periodic benefit cost (credit) for defined benefit plan. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 6 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e2709-114920 Reference 2: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 55 -Paragraph 17 -URI http://asc.fasb.org/extlink&oid=118257860&loc=d3e4179-114921 Reference 3: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 55 -Paragraph 18 -URI http://asc.fasb.org/extlink&oid=118257860&loc=d3e4587-114921 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (h) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 + Details Name: us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: duration

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- Definition Amount of cost for actuarial present value of benefits attributed to service rendered by employee for defined benefit plan. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (h)(1) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 Reference 2: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 55 -Paragraph 17 -URI http://asc.fasb.org/extlink&oid=118257860&loc=d3e4179-114921 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 6 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e2709-114920 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 Reference 5: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 55 -Paragraph 18 -URI http://asc.fasb.org/extlink&oid=118257860&loc=d3e4587-114921 + Details Name: us-gaap_DefinedBenefitPlanServiceCost Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: duration

X

- Details Name: us-gaap_RetirementPlanTypeAxis=us-gaap_PensionPlansDefinedBenefitMember Namespace Prefix: Data Type: na Balance Type: Period Type:

X

- Details Name: cma_DefinedBenefitsComponentsAxis=cma_SalariesandbenefitsexpenseMember Namespace Prefix: Data Type: na Balance Type: Period Type:

X

- Details Name: cma_DefinedBenefitsComponentsAxis=cma_ComponentrecognizedinnoninterestexpenseMember Namespace Prefix: Data Type: na Balance Type: Period Type:

X

- Details Name: us-gaap_RetirementPlanTypeAxis=us-gaap_SupplementalEmployeeRetirementPlanDefinedBenefitMember Namespace Prefix: Data Type: na Balance Type: Period Type:

X

- Details Name: us-gaap_RetirementPlanTypeAxis=us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember Namespace Prefix: Data Type: na Balance Type: Period Type:

v3.20.2

Income Taxes And Tax-Related Items Income Taxes And Tax-Related Items (Narrative) (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2020	Dec. 31, 2019
Unrecognized tax benefits	$ 18	$ 17
Tax-related interest and penalties payable	6	8
Net deferred tax assets	11	42
State net operating loss carryforwards	3	3
Valuation allowance for deferred tax assets	3	$ 3
Unrecognized Tax Benefits, Decrease Resulting from Settlements with Taxing Authorities	$ 1
Minimum
Years state net operating loss carryforwards expire	Dec. 31, 2020
Maximum
Years state net operating loss carryforwards expire	Dec. 31, 2029

X

- Definition Amount, after allocation of valuation allowances and deferred tax liability, of deferred tax asset attributable to deductible differences and carryforwards, without jurisdictional netting. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32537-109319 + Details Name: us-gaap_DeferredTaxAssetsLiabilitiesNet Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: instant

X

- Definition Amount before allocation of valuation allowances of deferred tax asset attributable to deductible state and local operating loss carryforwards. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32632-109319 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32621-109319 + Details Name: us-gaap_DeferredTaxAssetsOperatingLossCarryforwardsStateAndLocal Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: instant

X

- Definition Amount of deferred tax assets for which it is more likely than not that a tax benefit will not be realized. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32537-109319 + Details Name: us-gaap_DeferredTaxAssetsValuationAllowance Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: credit Period Type: instant

X

- Definition Expiration date of each operating loss carryforward included in operating loss carryforward, in CCYY-MM-DD format. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32559-109319 + Details Name: us-gaap_OperatingLossCarryforwardsExpirationDate Namespace Prefix: us-gaap_ Data Type: xbrli:dateItemType Balance Type: na Period Type: duration

X

- Definition Amount of unrecognized tax benefits. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 45 -Paragraph 10B -URI http://asc.fasb.org/extlink&oid=120406818&loc=SL37586934-109318 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 15A -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=84230637&loc=SL6600010-109319 + Details Name: us-gaap_UnrecognizedTaxBenefits Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: credit Period Type: instant

X

- Definition Amount of decrease in unrecognized tax benefits resulting from settlements with taxing authorities. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 15A -Subparagraph (a)(3) -URI http://asc.fasb.org/extlink&oid=84230637&loc=SL6600010-109319 + Details Name: us-gaap_UnrecognizedTaxBenefitsDecreasesResultingFromSettlementsWithTaxingAuthorities Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: duration

X

- Definition Amount accrued for interest on an underpayment of income taxes and penalties related to a tax position claimed or expected to be claimed in the tax return. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 15 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32718-109319 + Details Name: us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: credit Period Type: instant

X

- Details Name: srt_RangeAxis=srt_MinimumMember Namespace Prefix: Data Type: na Balance Type: Period Type:

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- Details Name: srt_RangeAxis=srt_MaximumMember Namespace Prefix: Data Type: na Balance Type: Period Type:

v3.20.2

Contingent Liabilities (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Loss Contingencies [Line Items]
Legal fees	$ 5	$ 4	$ 7	$ 5
Pending Litigation | Minimum
Loss Contingencies [Line Items]
Loss contingency, estimate of possible loss	0		0
Pending Litigation | Maximum
Loss Contingencies [Line Items]
Loss contingency, estimate of possible loss	$ 46		$ 46

X

- Definition The amount of expense provided in the period for legal costs incurred on or before the balance sheet date pertaining to resolved, pending or threatened litigation, including arbitration and mediation proceedings. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.3) -URI http://asc.fasb.org/extlink&oid=120395209&loc=SL114868664-224227 + Details Name: us-gaap_LegalFees Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: duration

X

- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details Name: us-gaap_LossContingenciesLineItems Namespace Prefix: us-gaap_ Data Type: xbrli:stringItemType Balance Type: na Period Type: duration

X

- Definition Reflects the estimated amount of loss from the specified contingency as of the balance sheet date. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 450 -SubTopic 20 -Section 50 -Paragraph 4 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=121557415&loc=d3e14435-108349 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 450 -SubTopic 20 -Section 50 -Paragraph 9 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=121557415&loc=d3e14557-108349 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 460 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=121555522&loc=d3e12021-110248 + Details Name: us-gaap_LossContingencyEstimateOfPossibleLoss Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: instant

X

- Details Name: us-gaap_LitigationStatusAxis=us-gaap_PendingLitigationMember Namespace Prefix: Data Type: na Balance Type: Period Type:

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- Details Name: srt_RangeAxis=srt_MinimumMember Namespace Prefix: Data Type: na Balance Type: Period Type:

X

- Details Name: srt_RangeAxis=srt_MaximumMember Namespace Prefix: Data Type: na Balance Type: Period Type:

v3.20.2

Business Segment Information (Narrative) (Details)	6 Months Ended
	Jun. 30, 2020 segments markets
Segment Reporting [Abstract]
Number of Major Business Segments | segments	3
Number of Primary Market Segments | markets	3

X

- Definition Number of Geographic Markets + References No definition available. + Details Name: cma_NumberOfGeographicMarkets Namespace Prefix: cma_ Data Type: xbrli:integerItemType Balance Type: na Period Type: duration

X

- Definition Number of Major Business Segments + References No definition available. + Details Name: cma_NumberOfMajorBusinessSegments Namespace Prefix: cma_ Data Type: xbrli:integerItemType Balance Type: na Period Type: duration

X

- References No definition available. + Details Name: us-gaap_SegmentReportingAbstract Namespace Prefix: us-gaap_ Data Type: xbrli:stringItemType Balance Type: na Period Type: duration

v3.20.2

Business Segment Information (Business Segment Financial Results) (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Net interest income (expense)		$ 471	$ 603	$ 984	$ 1,209
Provision for credit losses		138	44	549	31
Noninterest income		247	250	484	488
Noninterest expenses		440	424	865	857
(Benefit) provision for income taxes		27	87	6	172
Net income		113	298	48	637
Net credit-related charge-offs (recoveries)		50	33	134	44
Assets, average		81,644	71,252	77,454	70,515
Loans, average		53,498	50,963	51,551	50,323
Deposits, average		$ 64,282	$ 54,995	$ 60,524	$ 54,498
Return on average assets	[1]	0.55%	1.68%	0.12%	1.82%
Efficiency ratio	[2]	61.14%	49.65%	58.80%	50.23%
Commercial Bank
Net interest income (expense)		$ 402	$ 420	$ 782	$ 832
Provision for credit losses		117	52	513	46
Noninterest income		144	136	271	272
Noninterest expenses		207	195	401	393
(Benefit) provision for income taxes		47	71	27	153
Net income		175	238	112	512
Net credit-related charge-offs (recoveries)		48	35	131	47
Assets, average		47,392	45,321	45,823	44,619
Loans, average		45,914	43,932	44,253	43,241
Deposits, average		$ 36,318	$ 28,251	$ 33,274	$ 28,356
Return on average assets	[1]	1.49%	2.11%	0.49%	2.31%
Efficiency ratio	[2]	37.67%	34.98%	38.05%	35.61%
Retail Bank
Net interest income (expense)		$ 120	$ 146	$ 245	$ 292
Provision for credit losses		5	1	8	(3)
Noninterest income		24	33	52	64
Noninterest expenses		155	147	304	292
(Benefit) provision for income taxes		(4)	7	(4)	16
Net income		(12)	24	(11)	51
Net credit-related charge-offs (recoveries)		1	0	2	0
Assets, average		3,306	2,839	3,085	2,826
Loans, average		2,479	2,107	2,277	2,105
Deposits, average		$ 22,647	$ 20,649	$ 21,921	$ 20,560
Return on average assets	[1]	(0.21%)	0.44%	(0.10%)	0.49%
Efficiency ratio	[2]	107.15%	82.26%	101.41%	81.80%
Wealth Management
Net interest income (expense)		$ 40	$ 46	$ 81	$ 93
Provision for credit losses		16	(5)	28	(10)
Noninterest income		66	68	136	132
Noninterest expenses		73	67	145	139
(Benefit) provision for income taxes		3	13	9	23
Net income		14	39	35	73
Net credit-related charge-offs (recoveries)		1	(2)	1	(3)
Assets, average		5,191	5,071	5,134	5,121
Loans, average		5,077	4,930	5,007	4,983
Deposits, average		$ 4,217	$ 3,740	$ 4,120	$ 3,770
Return on average assets	[1]	1.00%	3.10%	1.34%	2.88%
Efficiency ratio	[2]	69.86%	58.99%	67.00%	61.67%
Finance
Net interest income (expense)		$ (95)	$ (23)	$ (139)	$ (37)
Provision for credit losses		0	0	0	0
Noninterest income		11	13	25	17
Noninterest expenses		1	0	1	1
(Benefit) provision for income taxes		(20)	(4)	(28)	(8)
Net income		(65)	(6)	(87)	(13)
Net credit-related charge-offs (recoveries)		0	0	0	0
Assets, average		14,500	13,907	14,393	13,747
Loans, average		0	0	0	0
Deposits, average		950	2,174	1,043	1,655
Other
Net interest income (expense)		4	14	15	29
Provision for credit losses		0	(4)	0	(2)
Noninterest income		2	0	0	3
Noninterest expenses		4	15	14	32
(Benefit) provision for income taxes		1	0	2	(12)
Net income		1	3	(1)	14
Net credit-related charge-offs (recoveries)		0	0	0	0
Assets, average		11,255	4,114	9,019	4,202
Loans, average		28	(6)	14	(6)
Deposits, average		$ 150	$ 181	$ 166	$ 157
[1] Return on average assets is calculated based on the greater of average assets or average liabilities and attributed equity. [2] Noninterest expenses as a percentage of the sum of net interest income and noninterest income excluding net gains (losses) from securities and a derivative contract tied to the conversion rate of Visa Class B shares.

X

- Definition The aggregate average balances of all deposit liabilities held by the entity, including foreign and domestic, interest and noninterest bearing; may include demand deposits, saving deposits, Negotiable Order of Withdrawal (NOW) and time deposits among others. + References No definition available. + Details Name: cma_AverageBalanceDuringPeriodDeposits Namespace Prefix: cma_ Data Type: xbrli:monetaryItemType Balance Type: credit Period Type: duration

X

- Definition Reflects the average aggregate gross carrying amount of all categories of loans and leases held in portfolio, after deducting deferred income, but before deducting the allowance for losses on loans and leases. + References No definition available. + Details Name: cma_AverageBalanceDuringPeriodLoansAndLeasesReceivableNetOfDeferredIncome Namespace Prefix: cma_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: duration

X

- Definition Noninterest expense for the period as a percent of the sum of net interest income (expense) FTE and noninterest income (excluding net securities gains(losses)) for the period. + References No definition available. + Details Name: cma_EfficiencyRatio Namespace Prefix: cma_ Data Type: num:percentItemType Balance Type: na Period Type: duration

X

- Definition The sum of net loan and lease charge-offs and charge-offs associated with lending-related commitments. + References No definition available. + Details Name: cma_NetCreditRelatedChargeOffs Namespace Prefix: cma_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: duration

X

- Definition Net income for the period as a percent of average assets for the period. + References No definition available. + Details Name: cma_ReturnOnAverageAssets Namespace Prefix: cma_ Data Type: num:percentItemType Balance Type: na Period Type: duration

X

- Definition Amount of average assets attributed to the reportable segment. + References No definition available. + Details Name: cma_SegmentReportingAverageAssets Namespace Prefix: cma_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: duration

X

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- Definition Total aggregate amount of all noninterest expense. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 220 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-04.14) -URI http://asc.fasb.org/extlink&oid=120399700&loc=SL114874048-224260 + Details Name: us-gaap_NoninterestExpense Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: duration

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- Definition The total amount of noninterest income which may be derived from: (1) fees and commissions; (2) premiums earned; (3) insurance policy charges; (4) the sale or disposal of assets; and (5) other sources not otherwise specified. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 220 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-04.13) -URI http://asc.fasb.org/extlink&oid=120399700&loc=SL114874048-224260 + Details Name: us-gaap_NoninterestIncome Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: credit Period Type: duration

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v3.20.2

Business Segment Information (Market Segment Financial Results) (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Net interest income (expense)		$ 471	$ 603	$ 984	$ 1,209
Provision for credit losses		138	44	549	31
Noninterest income		247	250	484	488
Noninterest expenses		440	424	865	857
(Benefit) provision for income taxes		27	87	6	172
Net income		113	298	48	637
Net credit-related charge-offs (recoveries)		50	33	134	44
Assets, average		81,644	71,252	77,454	70,515
Loans, average		53,498	50,963	51,551	50,323
Deposits, average		$ 64,282	$ 54,995	$ 60,524	$ 54,498
Return on average assets	[1]	0.55%	1.68%	0.12%	1.82%
Efficiency ratio	[2]	61.14%	49.65%	58.80%	50.23%
Michigan
Net interest income (expense)		$ 159	$ 186	$ 322	$ 373
Provision for credit losses		40	(10)	64	(5)
Noninterest income		64	72	136	144
Noninterest expenses		139	134	279	273
(Benefit) provision for income taxes		8	30	23	56
Net income		36	104	92	193
Net credit-related charge-offs (recoveries)		0	0	3	4
Assets, average		13,643	13,239	13,269	13,157
Loans, average		13,014	12,704	12,601	12,631
Deposits, average		$ 23,460	$ 19,816	$ 22,104	$ 19,854
Return on average assets	[1]	0.59%	2.01%	0.81%	1.89%
Efficiency ratio	[2]	62.08%	52.04%	60.46%	52.85%
California
Net interest income (expense)		$ 176	$ 208	$ 358	$ 411
Provision for credit losses		51	(4)	102	(5)
Noninterest income		36	40	72	80
Noninterest expenses		103	99	201	199
(Benefit) provision for income taxes		13	39	30	76
Net income		45	114	97	221
Net credit-related charge-offs (recoveries)		4	7	15	4
Assets, average		18,948	19,108	18,664	19,020
Loans, average		18,663	18,806	18,346	18,730
Deposits, average		$ 18,463	$ 16,314	$ 17,965	$ 16,276
Return on average assets	[1]	0.93%	2.38%	1.02%	2.35%
Efficiency ratio	[2]	48.61%	40.07%	46.77%	40.49%
Texas
Net interest income (expense)		$ 116	$ 124	$ 231	$ 248
Provision for credit losses		31	49	321	38
Noninterest income		30	34	60	66
Noninterest expenses		91	84	175	169
(Benefit) provision for income taxes		4	6	(46)	25
Net income		20	19	(159)	82
Net credit-related charge-offs (recoveries)		46	26	116	39
Assets, average		11,597	11,342	11,371	11,128
Loans, average		11,184	10,684	10,870	10,474
Deposits, average		$ 10,209	$ 8,668	$ 9,705	$ 8,682
Return on average assets	[1]	0.68%	0.69%	(2.82%)	1.47%
Efficiency ratio	[2]	61.88%	52.86%	60.07%	53.74%
Other Markets
Net interest income (expense)		$ 111	$ 94	$ 197	$ 185
Provision for credit losses		16	13	62	5
Noninterest income		104	91	191	178
Noninterest expenses		102	92	195	183
(Benefit) provision for income taxes		21	16	25	35
Net income		76	64	106	140
Net credit-related charge-offs (recoveries)		0	0	0	(3)
Assets, average		11,732	9,542	10,754	9,261
Loans, average		10,640	8,775	9,735	8,494
Deposits, average		$ 11,050	$ 7,842	$ 9,541	$ 7,874
Return on average assets	[1]	2.53%	2.75%	1.99%	3.06%
Efficiency ratio	[2]	47.41%	49.36%	50.25%	50.30%
Finance & Other
Net interest income (expense)		$ (91)	$ (9)	$ (124)	$ (8)
Provision for credit losses		0	(4)	0	(2)
Noninterest income		13	13	25	20
Noninterest expenses		5	15	15	33
(Benefit) provision for income taxes		(19)	(4)	(26)	(20)
Net income		(64)	(3)	(88)	1
Net credit-related charge-offs (recoveries)		0	0	0	0
Assets, average		25,724	18,021	23,396	17,949
Loans, average		(3)	(6)	(1)	(6)
Deposits, average		$ 1,100	$ 2,355	$ 1,209	$ 1,812
[1] Return on average assets is calculated based on the greater of average assets or average liabilities and attributed equity. [2] Noninterest expenses as a percentage of the sum of net interest income and noninterest income excluding net gains (losses) from securities and a derivative contract tied to the conversion rate of Visa Class B shares.

X

- Definition The aggregate average balances of all deposit liabilities held by the entity, including foreign and domestic, interest and noninterest bearing; may include demand deposits, saving deposits, Negotiable Order of Withdrawal (NOW) and time deposits among others. + References No definition available. + Details Name: cma_AverageBalanceDuringPeriodDeposits Namespace Prefix: cma_ Data Type: xbrli:monetaryItemType Balance Type: credit Period Type: duration

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X

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- Definition Net income for the period as a percent of average assets for the period. + References No definition available. + Details Name: cma_ReturnOnAverageAssets Namespace Prefix: cma_ Data Type: num:percentItemType Balance Type: na Period Type: duration

X

- Definition Amount of average assets attributed to the reportable segment. + References No definition available. + Details Name: cma_SegmentReportingAverageAssets Namespace Prefix: cma_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: duration

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- Definition The net amount of operating interest income (expense). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 220 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-04.10) -URI http://asc.fasb.org/extlink&oid=120399700&loc=SL114874048-224260 + Details Name: us-gaap_InterestIncomeExpenseNet Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: credit Period Type: duration

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- Definition Total aggregate amount of all noninterest expense. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 220 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-04.14) -URI http://asc.fasb.org/extlink&oid=120399700&loc=SL114874048-224260 + Details Name: us-gaap_NoninterestExpense Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: debit Period Type: duration

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- Definition The total amount of noninterest income which may be derived from: (1) fees and commissions; (2) premiums earned; (3) insurance policy charges; (4) the sale or disposal of assets; and (5) other sources not otherwise specified. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 220 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-04.13) -URI http://asc.fasb.org/extlink&oid=120399700&loc=SL114874048-224260 + Details Name: us-gaap_NoninterestIncome Namespace Prefix: us-gaap_ Data Type: xbrli:monetaryItemType Balance Type: credit Period Type: duration

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v3.20.2

Revenue from Contracts with Customers (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers		$ 188	$ 189	$ 373	$ 373
Other sources of noninterest income		59	61	111	115
Total noninterest income		247	250	484	488
Commercial Bank
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers		104	93	193	185
Other sources of noninterest income		40	43	78	87
Total noninterest income		144	136	271	272
Retail Bank
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers		21	31	49	60
Other sources of noninterest income		3	2	3	4
Total noninterest income		24	33	52	64
Wealth Management
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers		63	65	131	128
Other sources of noninterest income		3	3	5	4
Total noninterest income		66	68	136	132
Finance & Other
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers		0	0	0	0
Other sources of noninterest income		13	13	25	20
Total noninterest income		13	13	25	20
Credit and Debit Card [Member]
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers		68	65	127	128
Credit and Debit Card [Member] | Commercial Bank
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers		59	54	108	107
Credit and Debit Card [Member] | Retail Bank
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers		8	10	17	19
Credit and Debit Card [Member] | Wealth Management
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers		1	1	2	2
Credit and Debit Card [Member] | Finance & Other
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers		0	0	0	0
Service charges on deposit accounts
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers		42	51	91	102
Service charges on deposit accounts | Commercial Bank
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers		30	33	62	66
Service charges on deposit accounts | Retail Bank
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers		11	17	27	34
Service charges on deposit accounts | Wealth Management
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers		1	1	2	2
Service charges on deposit accounts | Finance & Other
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers		0	0	0	0
Fiduciary income
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers		52	52	106	101
Fiduciary income | Commercial Bank
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers		0	0	0	0
Fiduciary income | Retail Bank
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers		0	0	0	0
Fiduciary income | Wealth Management
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers		52	52	106	101
Fiduciary income | Finance & Other
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers		0	0	0	0
Commercial loan servicing fees
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers	[1]	4	4	8	8
Commercial loan servicing fees | Commercial Bank
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers	[1]	4	4	8	8
Commercial loan servicing fees | Retail Bank
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers	[1]	0	0	0	0
Commercial loan servicing fees | Wealth Management
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers	[1]	0	0	0	0
Commercial loan servicing fees | Finance & Other
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers	[1]	0	0	0	0
Brokerage Commissions Revenue [Member]
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers		5	7	12	14
Brokerage Commissions Revenue [Member] | Commercial Bank
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers		0	0	0	0
Brokerage Commissions Revenue [Member] | Retail Bank
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers		0	0	0	0
Brokerage Commissions Revenue [Member] | Wealth Management
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers		5	7	12	14
Brokerage Commissions Revenue [Member] | Finance & Other
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers		0	0	0	0
Other noninterest income
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers	[2]	17	10	29	20
Other noninterest income | Commercial Bank
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers	[2]	11	2	15	4
Other noninterest income | Retail Bank
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers	[2]	2	4	5	7
Other noninterest income | Wealth Management
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers	[2]	4	4	9	9
Other noninterest income | Finance & Other
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers	[2]	$ 0	$ 0	$ 0	$ 0
[1] Included in commercial lending fees on the Consolidated Statements of Comprehensive Income. [2] Excludes derivative, warrant and other miscellaneous income.

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