Comerica (CMA) 10-K 11 Feb 20 2019 FY Annual report Financial data

Document And Entity Information

Document And Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2019	Feb. 07, 2020	Jun. 28, 2019
Document And Entity Information [Abstract]
Document Annual Report	true
Entity Incorporation, State or Country Code	DE
City Area Code	(214)
Local Phone Number	462-6831
Title of 12(b) Security	Common Stock, $5 par value
Document Type	10-K
Document Period End Date	Dec. 31, 2019
Entity File Number	1-10706
Amendment Flag	false
Entity Registrant Name	Comerica Incorporated
Entity Central Index Key	0000028412
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	FY
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		141,346,049
Entity Shell Company	false
Entity Emerging Growth Company	false
Entity Small Business	false
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Public Float			$ 10,700,000,000
Document Transition Report	false
Trading Symbol	CMA
Security Exchange Name	NYSE
Entity Address, Address Line One	1717 Main Street, MC 6404
Entity Address, City or Town	Dallas
Entity Address, State or Province	TX
Entity Address, Postal Zip Code	75201
Entity Tax Identification Number	38-1998421

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
ASSETS
Cash and due from banks	$ 973	$ 1,390
Interest-bearing deposits with banks	4,845	3,171
Other short-term investments	155	134
Investment securities available-for-sale	12,398	12,045
Commercial loans	31,473	31,976
Real estate construction loans	3,455	3,077
Commercial mortgage loans	9,559	9,106
Lease financing	588	507
International loans	1,009	1,013
Residential mortgage loans	1,845	1,970
Consumer loans	2,440	2,514
Total loans	50,369	50,163
Less allowance for loan losses	(637)	(671)
Net loans	49,732	49,492
Premises and equipment	457	475
Accrued income and other assets	4,842	4,111
Total assets	73,402	70,818
LIABILITIES AND SHAREHOLDERS' EQUITY
Noninterest-bearing deposits	27,382	28,690
Money market and interest-bearing checking deposits	24,527	22,560
Savings deposits	2,184	2,172
Customer certificates of deposit	2,978	2,131
Other time deposits	133	0
Foreign office time deposits	91	8
Total interest-bearing deposits	29,913	26,871
Total deposits	57,295	55,561
Short-term borrowings	71	44
Accrued expenses and other liabilities	1,440	1,243
Medium- and long-term debt	7,269	6,463
Total liabilities	66,075	63,311
Common stock - $5 par value: Authorized - 325,000,000 shares; Issued - 228,164,824 shares	1,141	1,141
Capital surplus	2,174	2,148
Accumulated other comprehensive loss	(235)	(609)
Retained earnings	9,538	8,781
Less cost of common stock in treasury - 86,069,234 shares at 12/31/19 and 68,081,176 shares at 12/31/18	(5,291)	(3,954)
Total shareholders' equity	7,327	7,507
Total liabilities and shareholders' equity	$ 73,402	$ 70,818

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2019	Dec. 31, 2018
Statement of Financial Position [Abstract]
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	86,069,234	68,081,176

Consolidated Statements Of Inco

Consolidated Statements Of Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019		Dec. 31, 2018		Dec. 31, 2017
INTEREST INCOME
Interest and fees on loans	$ 2,439		$ 2,262		$ 1,872
Interest on investment securities	297		265		250
Interest on short-term investments	71		92		60
Total interest income	2,807		2,619		2,182
INTEREST EXPENSE
Interest on deposits	262		122		42
Interest on short-term borrowings	9		1		3
Interest on medium- and long-term debt	197	[1]	144	[1]	76
Total interest expense	468		267		121
Net interest income	2,339		2,352		2,061
Provision for credit losses	74		(1)		74
Net interest income after provision for credit losses	2,265		2,353		1,987
NONINTEREST INCOME
Card fees	257		244		333
Fiduciary income	206		206		198
Service charges on deposit accounts	203		211		227
Commercial lending fees	91		85		85
Foreign exchange income	44		47		45
Bank-owned life insurance	41		39		43
Letter of credit fees	38		40		45
Brokerage fees	28		27		23
Net securities losses	(7)		(19)		0
Other noninterest income	109		96		108
Total noninterest income	1,010		976		1,107
NONINTEREST EXPENSES
Salaries and benefits expense	1,020		1,009		961
Outside processing fee expense	264		255		366
Occupancy expense	154		152		154
Software expense	117		125		126
Equipment expense	50		48		45
Advertising expense	34		30		28
FDIC insurance expense	23		42		51
Restructuring charges	0		53		45
Other noninterest expenses	81		80		84
Total noninterest expenses	1,743		1,794		1,860
Income before income taxes	1,532		1,535		1,234
Provision for income taxes	334		300		491
Net Income	1,198		1,235		743
Less income allocated to participating securities	7		8		5
Net income attributable to common shares	$ 1,191		$ 1,227		$ 738
Basic earnings per common share	$ 7.95		$ 7.31		$ 4.23
Diluted earnings per common share	$ 7.87		$ 7.20		$ 4.14
Cash dividends declared on common stock	$ 398		$ 309		$ 193
Cash dividends declared per common share	$ 2.68		$ 1.84		$ 1.09
[1]	Includes the effects of hedging.

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 1,198	$ 1,235	$ 743
Net unrealized holding gains (losses) arising during the period	257	(69)	(81)
Less reclassification adjustment for net securities losses included in net income	(8)	(20)	0
Less net losses realized as a yield adjustment in interest on investment securities	0	0	(3)
Change in net unrealized gains (losses) before income taxes	265	(49)	(78)
Change in net cash flow hedge gains before income taxes	44	0	0
Actuarial gain (loss) arising during the period	163	(191)	72
Amortization of actuarial net loss	(42)	(61)	(51)
Amortization of prior service credit	(27)	(27)	(27)
Change in defined benefit pension and other postretirement plans adjustment before income taxes	178	(157)	96
Total other comprehensive income (loss) before income taxes	487	(206)	18
Provision (benefit) for income taxes	113	(47)	(1)
Total other comprehensive income (loss), net of tax	374	(159)	19
Comprehensive Income	$ 1,572	$ 1,076	$ 762

Consolidated Statements Of Chan

Consolidated Statements Of Changes In Shareholders' Equity - USD ($) shares in Millions, $ in Millions	Total	Common Stock	Capital Surplus	Accumulated Other Comprehensive Loss	Retained Earnings	Treasury Stock
BALANCE (in shares)		175.3
Cumulative effect of change in accounting principle(s)	$ 1		$ 3		$ (2)
BALANCE at Dec. 31, 2016	7,796	$ 1,141	2,135	$ (383)	7,331	$ (2,428)
Net income	743				743
Other comprehensive income (loss), net of tax	19			19
Cash dividends declared on common stock	(193)				(193)
Purchase of common stock	(544)					544
Purchase of common stock (in shares)		(7.5)
Net issuance of common stock under employee stock plans	102		(24)		(26)	152
Net issuance of common stock under employee stock plans (in shares)		3.3
Net issuance of common stock for warrants	0		(30)		(53)	83
Net issuance of common stock for warrants (in shares)		1.8
Share-based compensation	39		39
Reclassification of certain deferred tax effects	0			(87)	87
Other	0		(1)			1
BALANCE at Dec. 31, 2017	7,963	$ 1,141	2,122	(451)	7,887	(2,736)
BALANCE (in shares)		172.9
Cumulative effect of change in accounting principle(s)	15		0	1	14
Net income	1,235				1,235
Other comprehensive income (loss), net of tax	(159)			(159)
Cash dividends declared on common stock	(309)				(309)
Purchase of common stock	(1,329)		3			1,326
Purchase of common stock (in shares)		(14.9)
Net issuance of common stock under employee stock plans	43		(9)		(23)	75
Net issuance of common stock under employee stock plans (in shares)		1.5
Net issuance of common stock for warrants	0		(10)		(23)	33
Net issuance of common stock for warrants (in shares)		0.6
Share-based compensation	48		48
BALANCE at Dec. 31, 2018	7,507	$ 1,141	2,148	(609)	8,781	(3,954)
BALANCE (in shares)		160.1
Cumulative effect of change in accounting principle(s)	(14)			0	(14)
Net income	1,198				1,198
Other comprehensive income (loss), net of tax	374			374
Cash dividends declared on common stock	(398)				(398)
Purchase of common stock	(1,380)		0			1,380
Purchase of common stock (in shares)		(18.7)
Net issuance of common stock under employee stock plans	1		(13)		(29)	43
Net issuance of common stock under employee stock plans (in shares)		0.7
Share-based compensation	39		39
BALANCE at Dec. 31, 2019	$ 7,327	$ 1,141	$ 2,174	$ (235)	$ 9,538	$ (5,291)
BALANCE (in shares)		142.1

Consolidated Statements Of Ch_2

Consolidated Statements Of Changes In Shareholders' Equity (Parenthetical) - $ / shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statement of Changes in Equity Parenthetical [Abstract]
Cash dividends declared per common share	$ 2.68	$ 1.84	$ 1.09

Consolidated Statements Of Cash

Consolidated Statements Of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
OPERATING ACTIVITIES
Net income	$ 1,198	$ 1,235	$ 743
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for credit losses	74	(1)	74
Provision for deferred income taxes	12	24	79
Depreciation and amortization	114	120	121
Net periodic defined benefit credit	(29)	(18)	(18)
Share-based compensation expense	39	48	39
Net amortization of securities	2	3	6
Accretion of loan purchase discount	0	(1)	(3)
Net securities losses	7	19	0
Net gains on sales of foreclosed property	1	(1)	(3)
Net change in accrued income receivable	17	(45)	(33)
Net change in accrued expenses payable	(27)	49	41
Other, net	(318)	184	39
Net cash provided by operating activities	1,090	1,616	1,085
INVESTING ACTIVITIES
Maturities and redemptions of investment securities available-for-sale	2,262	1,781	1,615
Sales of investment securities available-for-sale	987	1,256	1,259
Purchases of investment securities available-for-sale	(3,346)	(3,032)	(3,112)
Maturities and redemptions of investment securities held-to-maturity	0	0	319
Net change in loans	(324)	(1,045)	(175)
Proceeds from sales of foreclosed property	1	8	22
Net increase in premises and equipment	(86)	(90)	(69)
Purchases of Federal Home Loan Bank stock	(201)	(41)	(42)
Redemptions of Federal Home Loan Bank stock	201	0	42
Proceeds from bank-owned life insurance settlements	10	9	18
Other, net	2	(2)	3
Net cash used in investing activities	(494)	(1,156)	(120)
FINANCING ACTIVITIES
Net change in deposits	1,711	(2,082)	(1,180)
Net change in short-term borrowings	27	34	(15)
Maturities of medium- and long-term debt	(350)	0	(500)
Issuances and advances of medium- and long-term debt	1,050	1,850	0
Terminations of medium- and long-term debt	0	0	(16)
Repurchases of common stock	(1,394)	(1,338)	(560)
Cash dividends paid on common stock	(402)	(263)	(180)
Issuances of common stock under employee stock plans	18	52	118
Other, net	1	3	(5)
Net cash provided by (used in) financing activities	661	(1,744)	(2,338)
Net increase (decrease) in cash and cash equivalents	1,257	(1,284)	(1,373)
Cash and cash equivalents at beginning of period	4,561	5,845	7,218
Cash and cash equivalents at end of period	5,818	4,561	5,845
Interest paid	462	261	122
Income taxes paid	266	200	336
Noncash investing and financing activities:
Loans transferred to other real estate	12	3	8
Residential mortgage-backed securities transferred from held-to-maturity to available-for-sale	0	1,266	0
Securities transferred from available-for-sale to equity securities	$ 0	$ 81	$ 0

Basis of Presentation and Accou

Basis of Presentation and Accounting Policies	12 Months Ended
	Dec. 31, 2019
Accounting Policies [Abstract]
Basis of Presentation and Accounting Policies	BASIS OF PRESENTATION AND ACCOUNTING POLICIES Organization Comerica Incorporated (the Corporation) is a registered financial holding company headquartered in Dallas, Texas. The Corporation’s major business segments are the Business Bank, the Retail Bank and Wealth Management. The Corporation operates in three primary geographic markets: Michigan, California and Texas. For further discussion of each business segment and primary geographic market, refer to Note 22 . The Corporation and its banking subsidiaries are regulated at both the state and federal levels. The accounting and reporting policies of the Corporation conform to United States (U.S.) generally accepted accounting principles (GAAP). The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect reported amounts and disclosures. Actual results could differ from these estimates. Certain amounts in the financial statements for prior years have been reclassified to conform to the current financial statement presentation. The following summarizes the significant accounting policies of the Corporation applied in the preparation of the accompanying consolidated financial statements. Principles of Consolidation The consolidated financial statements include the accounts of the Corporation and the accounts of those subsidiaries that are majority owned and in which the Corporation has a controlling financial interest. The Corporation consolidates entities not determined to be variable interest entities (VIEs) when it holds a controlling financial interest and uses the cost or equity method when it holds less than a controlling financial interest. In consolidation, all significant intercompany accounts and transactions are eliminated. The results of operations of companies acquired are included from the date of acquisition. The Corporation holds investments in certain legal entities that are considered VIEs. In general, a VIE is an entity that either (1) has an insufficient amount of equity to carry out its principal activities without additional subordinated financial support, (2) has a group of equity owners that are unable to make significant decisions about its activities, or (3) has a group of equity owners that do not have the obligation to absorb losses or the right to receive returns generated by its operations. If any of these characteristics are present, the entity is subject to a variable interests consolidation model, and consolidation is based on variable interests, not on voting interests. Variable interests are defined as contractual ownership or other money interests in an entity that change with fluctuations in the entity’s net asset value. The primary beneficiary is required to consolidate the VIE. The primary beneficiary is defined as the party that has both the power to direct the activities of the VIE that most significantly impact the entity’s economic performance and the obligation to absorb losses or the right to receive benefits that could be significant to the VIE. The maximum potential exposure to losses relative to investments in VIEs is generally limited to the sum of the outstanding book basis and unfunded commitments for future investments. The Corporation evaluates its investments in VIEs, both at inception and when there is a change in circumstances that requires reconsideration, to determine if the Corporation is the primary beneficiary and consolidation is required. The Corporation accounts for unconsolidated VIEs using either the proportional, cost or equity method. These investments comprise investments in community development projects which generate tax credits to their investors and are included in accrued income and other assets on the Consolidated Balance Sheets. The proportional method is used for investments in affordable housing projects that qualify for the low-income housing tax credit (LIHTC). The equity method is used for other investments where the Corporation has the ability to exercise significant influence over the entity’s operation and financial policies. Other unconsolidated equity investments that do not meet the criteria to be accounted for under the equity method are accounted for under the cost method. Amortization and other write-downs of LIHTC investments are presented on a net basis as a component of the provision for income taxes, while income, amortization and write-downs from cost and equity method investments are recorded in other noninterest income on the Consolidated Statements of Income. Assets held in an agency or fiduciary capacity are not assets of the Corporation and are not included in the consolidated financial statements. See Note 9 for additional information about the Corporation’s involvement with VIEs. 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. Fair value is an estimate of the exchange price that would be received to sell an asset or paid to transfer a liability in an orderly transaction (i.e., not a forced transaction, such as a liquidation or distressed sale) between market participants at the measurement date. Fair value is based on the assumptions market participants would use when pricing an asset or liability. 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 impaired loans, 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. Fair value measurements and disclosures guidance establishes a three-level fair value hierarchy based on the markets in which the assets and liabilities are traded and the reliability of the assumptions used to determine fair value. The fair value hierarchy gives the highest priority to quoted prices in active markets and the lowest priority to unobservable data. Fair value measurements are separately disclosed by level within the fair value hierarchy. For assets and liabilities recorded at fair value, it is the Corporation’s policy to maximize the use of observable inputs and minimize the use of unobservable inputs when developing fair value measurements. Level 1 Valuation is based upon quoted prices for identical instruments traded in active markets. Level 2 Valuation is based upon quoted prices for similar instruments in active markets, quoted prices for identical or similar instruments in markets that are less active, and model-based valuation techniques for which all significant assumptions are observable in the market. Level 3 Valuation is generated from model-based techniques that use at least one significant assumption not observable in the market. These unobservable assumptions reflect estimates of assumptions that market participants would use in pricing the asset or liability. Valuation techniques include use of option pricing models, discounted cash flow models and similar techniques. The Corporation generally utilizes third-party pricing services to value Level 1 and Level 2 securities. Management reviews the methodologies and assumptions used by the third-party pricing services and evaluates the values provided, principally by comparison with other available market quotes for similar instruments and/or analysis based on internal models using available third-party market data. The Corporation may occasionally adjust certain values provided by the third-party pricing service when management believes, as the result of its review, that the adjusted price most appropriately reflects the fair value of the particular security. Fair value measurements for assets and liabilities where limited or no observable market data exists are based primarily upon estimates, often calculated based on the economic and competitive environment, the characteristics of the asset or liability and other factors. Therefore, the results cannot be determined with precision and may not be realized in an actual sale or immediate settlement of the asset or liability. Additionally, there may be inherent weaknesses in any calculation technique, and changes in the underlying assumptions used, including discount rates and estimates of future cash flows, could significantly affect the results of current or future values. Following are 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. The descriptions include an indication of the level of the fair value hierarchy in which the assets or liabilities are classified. Transfers of assets or liabilities between levels of the fair value hierarchy are recognized at the beginning of the reporting period, when applicable. Cash and due from banks, federal funds sold and interest-bearing deposits with banks Due to their short-term nature, the carrying amount of these instruments approximates the estimated fair value. As such, the Corporation classifies the estimated fair value of these instruments as Level 1. Deferred compensation plan assets and liabilities as well as equity securities with a readily determinable fair value The Corporation holds a portfolio of securities including equity securities and assets held related to deferred compensation plans. Securities and associated deferred compensation plan liabilities are recorded at fair value on a recurring basis and included in other short-term investments and accrued expenses and other liabilities, respectively, on the Consolidated Balance Sheets. Level 1 securities include assets related to deferred compensation plans, which are invested in mutual funds, U.S. Treasury securities that are traded by dealers or brokers in active over-the-counter markets and other securities traded on an active exchange, such as the New York Stock Exchange. Deferred compensation plan liabilities represent the fair value of the obligation to the employee, which corresponds to the fair value of the invested assets. Level 2 securities include municipal bonds and residential mortgage-backed securities issued by U.S. government-sponsored entities and corporate debt securities. The methods used to value equity securities and deferred compensation plan assets are the same as the methods used to value investment securities, discussed below. Investment securities Investment securities available-for-sale are recorded at fair value on a recurring basis. The Corporation discloses estimated fair values of investment securities held-to-maturity, which is determined in the same manner as investment securities available-for-sale. Level 1 securities include those traded on an active exchange, such as the New York Stock Exchange, U.S. Treasury securities that are traded by dealers or brokers in active over-the-counter markets and money market funds. Level 2 securities include residential mortgage-backed securities issued by U.S. government agencies and U.S. government-sponsored entities and corporate debt securities. The fair value of Level 2 securities is determined using quoted prices of securities with similar characteristics, or pricing models based on observable market data inputs, primarily interest rates, spreads and prepayment information. Securities classified as Level 3 represent securities in less liquid markets requiring significant management assumptions when determining fair value. The Corporate Treasury department, with appropriate oversight and approval provided by senior management, is responsible for the valuation of Level 3 securities. Valuation results, including an analysis of changes to the valuation methodology, are provided to senior management for review on a quarterly basis. Loans held-for-sale Loans held-for-sale, included in other short-term investments on the Consolidated Balance Sheets, are recorded at the lower of cost or fair value. Loans held-for-sale may be carried at fair value on a nonrecurring basis when fair value is less than cost. The fair value is based on what secondary markets are currently offering for portfolios with similar characteristics. As such, the Corporation classifies both loans held-for-sale subjected to nonrecurring fair value adjustments and the estimated fair value of loans held-for sale as Level 2. Loans The Corporation does not record loans at fair value on a recurring basis. However, the Corporation may establish a specific allowance for an impaired loan based on the fair value of the underlying collateral. Such loan values are reported as nonrecurring fair value measurements. Collateral values supporting individually evaluated impaired loans are evaluated quarterly. When management determines that the fair value of the collateral requires additional adjustments, either as a result of non-current appraisal value or when there is no observable market price, the Corporation classifies the impaired loan as Level 3. The Special Assets Group is responsible for performing quarterly credit quality reviews for all impaired loans as part of the quarterly allowance for loan losses process overseen by the Chief Credit Officer, during which valuation adjustments to updated collateral values are determined. The Corporation discloses fair value estimates for loans. The estimated fair value is determined based on characteristics such as loan category, repricing features and remaining maturity, and includes prepayment and credit loss estimates. Fair values are estimated using a discounted cash flow model that employs discount rates that reflects current pricing for loans with similar maturity and risk characteristics, including credit characteristics, and the cost of equity for the portfolio at the balance sheet date. The rates take into account the expected yield curve, as well as an adjustment for prepayment risk, when applicable. The Corporation classifies the estimated fair value of loans held for investment as Level 3. Customers’ liability on acceptances outstanding and acceptances outstanding Customers' liability on acceptances outstanding is included in accrued income and other assets and acceptances outstanding are included in accrued expenses and other liabilities on the Consolidated Balance Sheets. Due to their short-term nature, the carrying amount of these instruments approximates the estimated fair value. As such, the Corporation classifies the estimated fair value of these instruments as Level 1. Derivative assets and derivative liabilities Derivative instruments held or issued for risk management or customer-initiated activities are traded in over-the-counter markets where quoted market prices are not readily available. Fair value for over-the-counter derivative instruments is measured on a recurring basis using internally developed models that use primarily market observable inputs, such as yield curves and option volatilities. The Corporation manages credit risk on its derivative positions based on whether the derivatives are being settled through a clearinghouse or bilaterally with each counterparty. For derivative positions settled on a counterparty-by-counterparty basis, the Corporation calculates credit valuation adjustments, included in the fair value of these instruments, on the basis of its relationships at the counterparty portfolio/master netting agreement level. These credit valuation adjustments are determined by applying a credit spread for the counterparty or the Corporation, as appropriate, to the total expected exposure of the derivative after considering collateral and other master netting arrangements. These adjustments, which are considered Level 3 inputs, are based on estimates of current credit spreads to evaluate the likelihood of default. When credit valuation adjustments are significant to the overall fair value of a derivative, the Corporation classifies the over-the-counter derivative valuation in Level 3 of the fair value hierarchy; otherwise, over-the-counter derivative valuations are classified in Level 2. Nonmarketable equity securities The Corporation has a portfolio of indirect (through funds) private equity and venture capital investments with a carrying value of $5 million and unfunded commitments of less than $1 million , at December 31, 2019 . The investments are accounted for either on the cost or equity method and are individually reviewed for impairment on a quarterly basis by comparing the carrying value to the estimated fair value. These investments may be carried at fair value on a nonrecurring basis when they are deemed to be impaired and written down to fair value. Where there is not a readily determinable fair value, the Corporation estimates fair value for indirect private equity and venture capital investments based on the net asset value, as reported by the fund. The Corporation also holds restricted equity investments, primarily Federal Home Loan Bank (FHLB) and Federal Reserve Bank (FRB) stock. Restricted equity securities are not readily marketable and are recorded at cost (par value) in accrued income and other assets on the Consolidated Balance Sheets and evaluated for impairment based on the ultimate recoverability of the par value. No significant observable market data for these instruments is available. The Corporation considers the profitability and asset quality of the issuer, dividend payment history and recent redemption experience and believes its investments in FHLB and FRB stock are ultimately recoverable at par. Therefore, the carrying amount for these restricted equity investments approximates fair value. The Corporation classifies the estimated fair value of such investments as Level 1. The Corporation’s investment in FHLB stock totaled $163 million at both December 31, 2019 and 2018 , and its investment in FRB stock totaled $85 million at both December 31, 2019 and 2018 . Other real estate Other real estate is included in accrued income and other assets on the Consolidated Balance Sheets and includes primarily foreclosed property. Foreclosed property is initially recorded at fair value, less costs to sell, at the date of legal title transfer to the Corporation, establishing a new cost basis. Subsequently, foreclosed property is carried at the lower of cost or fair value, less costs to sell. Other real estate may be carried at fair value on a nonrecurring basis when fair value is less than cost. Fair value is based upon independent market prices, appraised value or management's estimate of the value of the property. The Special Assets Group obtains updated independent market prices and appraised values, as required by state regulation or deemed necessary based on market conditions, and determines if additional write-downs are necessary. On a quarterly basis, senior management reviews all other real estate and determines whether the carrying values are reasonable, based on the length of time elapsed since receipt of independent market price or appraised value and current market conditions. When management determines that the fair value of other real estate requires additional adjustments, either as a result of a non-current appraisal or when there is no observable market price, the Corporation classifies the other real estate as Level 3. Deposit liabilities The estimated fair value of checking, savings and certain money market deposit accounts is represented by the amounts payable on demand. The estimated fair value of term deposits is calculated by discounting the scheduled cash flows using the period-end rates offered on these instruments. As such, the Corporation classifies the estimated fair value of deposit liabilities as Level 2. Short-term borrowings The carrying amount of federal funds purchased, securities sold under agreements to repurchase and other short-term borrowings approximates the estimated fair value. As such, the Corporation classifies the estimated fair value of short-term borrowings as Level 1. Medium- and long-term debt The estimated fair value of the Corporation's medium- and long-term debt is based on quoted market values when available. If quoted market values are not available, the estimated fair value is based on the market values of debt with similar characteristics. The Corporation classifies the estimated fair value of medium- and long-term debt as Level 2. Credit-related financial instruments Credit-related financial instruments include unused commitments to extend credit and letters of credit. These instruments generate ongoing fees which are recognized over the term of the commitment. In situations where credit losses are probable, the Corporation records an allowance. The carrying value of these instruments included in accrued expenses and other liabilities on the Consolidated Balance Sheets, which includes the carrying value of the deferred fees plus the related allowance, approximates the estimated fair value. The Corporation classifies the estimated fair value of credit-related financial instruments as Level 3. For further information about fair value measurements refer to Note 2 . Other Short-Term Investments Other short-term investments include deferred compensation plan assets, equity securities with a readily determinable fair value and loans held-for-sale. Deferred compensation plan assets and equity securities are carried at fair value. Realized and unrealized gains or losses are included in other noninterest income on the Consolidated Statements of Income. Loans held-for-sale, typically residential mortgages originated with the intent to sell and occasionally including other loans transferred to held-for-sale, are carried at the lower of cost or fair value. Fair value is determined in the aggregate for each portfolio. Changes in fair value and gains or losses upon sale are included in other noninterest income on the Consolidated Statements of Income. Investment Securities Debt securities are classified as trading, available-for-sale or held-to-maturity. Trading securities are recorded at fair value, with unrealized gains and losses included in noninterest income on the Consolidated Statements of Income. Securities available-for-sale are recorded at fair value, with unrealized gains and losses, net of income taxes, reported as a separate component of other comprehensive income (OCI). Securities for which management has the intent and ability to hold to maturity are classified as held-to-maturity and recorded at amortized cost. Interest income is recognized using the interest method. Securities transferred from available-for-sale to held-to-maturity are reclassified at fair value on the date of transfer. The net unrealized gain (loss) at the date of transfer is included in historical cost and amortized over the remaining life of the related securities as a yield adjustment consistent with the amortization of the net unrealized gain (loss) included in accumulated other comprehensive loss on the same securities, resulting in no impact to net income. Debt securities are reviewed quarterly for possible other-than-temporary impairment (OTTI). In determining whether OTTI exists for debt securities in an unrealized loss position, the Corporation assesses the likelihood of selling the security prior to the recovery of its amortized cost basis. If the Corporation intends to sell the debt security or it is more likely than not that the Corporation will be required to sell the debt security prior to the recovery of its amortized cost basis, the debt security is written down to fair value, and the full amount of any impairment charge is recorded as a loss in net securities losses on the Consolidated Statements of Income. If the Corporation does not intend to sell the debt security and it is more likely than not that the Corporation will not be required to sell the debt security prior to recovery of its amortized cost basis, only the credit component of any impairment of a debt security is recognized as a loss in net securities losses on the Consolidated Statements of Income, with the remaining impairment recorded in OCI. Gains or losses on the sale of securities are computed based on the adjusted cost of the specific security sold. For further information on investment securities, refer to Note 3 . Loans Loans and leases originated and held for investment are recorded at the principal balance outstanding, net of unearned income, charge-offs and unamortized deferred fees and costs. Interest income is recognized on loans and leases using the interest method. The Corporation assesses all loan modifications to determine whether a restructuring constitutes a TDR. A restructuring is considered a TDR when a borrower is experiencing financial difficulty and the Corporation grants a concession to the borrower. TDRs on accrual status at the original contractual rate of interest are considered performing. Nonperforming TDRs include TDRs on nonaccrual status and loans which have been renegotiated to less than the original contractual rates (reduced-rate loans). All TDRs are considered impaired loans. Loan Origination Fees and Costs Substantially all loan origination fees and costs are deferred and amortized to net interest income over the life of the related loan or over the commitment period as a yield adjustment. Net deferred income on originated loans, including unearned income and unamortized costs, fees, premiums and discounts, totaled $103 million and $115 million at December 31, 2019 and 2018 , respectively. Loan fees on unused commitments and net origination fees related to loans sold are recognized in noninterest income. 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 traditional residential mortgage, home equity and other consumer loans. For further information on the Allowance for Credit Losses, refer to Note 4 . Allowance for Loan Losses The allowance for loan losses represents management’s assessment of probable, estimable losses inherent in the Corporation’s loan portfolio. The allowance for loan losses includes specific allowances, based on individual evaluations of certain loans, and allowances for homogeneous pools of loans with similar risk characteristics. The Corporation individually evaluates certain impaired loans on a quarterly basis and establishes specific allowances for such loans, if required. A loan is considered impaired when it is probable that interest or principal payments will not be made in accordance with the contractual terms of the loan agreement. Consistent with this definition, all loans for which the accrual of interest has been discontinued (nonaccrual loans) are considered impaired. The Corporation individually evaluates nonaccrual loans with book balances of $2 million or more and loans whose terms have been modified in a TDR with book balances of $1 million or more. The threshold for individual evaluation is revised on an infrequent basis, generally when economic circumstances change significantly. Specific allowances for impaired loans are estimated using one of several methods, including the estimated fair value of underlying collateral, observable market value of similar debt or discounted expected future cash flows. Collateral values supporting individually evaluated impaired loans are evaluated quarterly. Generally, appraisals are obtained or appraisal assumptions are updated annually, unless conditions dictate increased frequency. The Corporation may reduce the collateral value based upon the age of the appraisal and adverse developments in market conditions. Loans which do not meet the criteria to be evaluated individually are evaluated in homogeneous pools of loans with similar risk characteristics. Business loans are assigned to pools based on the Corporation's internal risk rating system. Internal risk ratings are assigned to each business loan at the time of approval and are subjected to subsequent periodic reviews by the Corporation’s senior management, generally at least annually or more frequently upon the occurrence of a circumstance that affects the credit risk of the loan. For business loans not individually evaluated, losses inherent to the pool are estimated by applying standard reserve factors to outstanding principal balances. Standard reserve factors are based on estimated probabilities of default for each internal risk rating, set to a default horizon based on an estimated loss emergence period, and loss given default. These factors are evaluated quarterly and updated annually, unless economic conditions necessitate a change, giving consideration to count-based borrower risk rating migration experience and trends, recent charge-off experience, current economic conditions and trends, changes in collateral values of properties securing loans, and trends with respect to past due and nonaccrual amounts. The allowance for business loans not individually evaluated 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 (i) risk factors that have not been fully addressed in internal risk ratings, (ii) imprecision in the risk rating system resulting from inaccuracy in assigning and/or entering risk ratings in the loan accounting system, (iii) market conditions and (iv) model imprecision. Risk factors that have not been fully addressed in internal risk ratings may include portfolios where recent historical losses exceed expected losses or known recent events are expected to alter risk ratings once evidence is acquired, portfolios where a certain level of concentration introduces added risk, or changes in the level and quality of experience held by lending management. An additional allowance for risk rating errors is calculated based on the results of risk rating accuracy assessments performed on samples of business loans conducted by the Corporation's asset quality review function, a function independent of the lending and credit groups responsible for assigning the initial internal risk rating at the time of approval. Qualitative adjustments for market conditions are determined based on an established framework. The determination of the appropriate adjustment is based on management's analysis of observable macroeconomic metrics, including consideration of regional metrics within the Corporation's footprint, internal credit risk movement and a qualitative assessment of the lending environment, including underwriting standards, current economic and political conditions, and other factors affecting credit quality. 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 assumption. The allowance for retail loans not individually evaluated is determined by applying estimated loss rates to various pools of loans within the portfolios with similar risk characteristics. Estimated loss rates for all pools are updated quarterly, incorp

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2019
Fair Value Disclosures [Abstract]
Fair Value Measurements	FAIR VALUE MEASUREMENTS Note 1 contains 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 December 31, 2019 and 2018 . (in millions) Total Level 1 Level 2 Level 3 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. (in millions) Total Level 1 Level 2 Level 3 December 31, 2018 Deferred compensation plan assets $ 88 $ 88 $ — $ — Equity securities 43 43 — — Investment securities available-for-sale: U.S. Treasury and other U.S. government agency securities 2,727 2,727 — — Residential mortgage-backed securities (a) 9,318 — 9,318 — Total investment securities available-for-sale 12,045 2,727 9,318 — Derivative assets: Interest rate contracts 67 — 58 9 Energy derivative contracts 189 — 189 — Foreign exchange contracts 19 — 19 — Total derivative assets 275 — 266 9 Total assets at fair value $ 12,451 $ 2,858 $ 9,584 $ 9 Derivative liabilities: Interest rate contracts $ 70 $ — $ 70 $ — Energy derivative contracts 186 — 186 — Foreign exchange contracts 13 — 13 — Total derivative liabilities 269 — 269 — Deferred compensation plan liabilities 88 88 — — Total liabilities at fair value $ 357 $ 88 $ 269 $ — (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 1, Level 2 and Level 3 fair value measurements during the years ended December 31, 2019 and 2018 . The following table summarizes the changes in Level 3 assets measured at fair value on a recurring basis for the years ended December 31, 2019 and 2018 . Net Realized/Unrealized Gains (Losses) (Pretax) Recorded in Earnings (b) Balance at Beginning of Period Change in Classification (a) Sales and Redemptions Balance at End of Period (in millions) Realized Unrealized Year Ended December 31, 2019 Derivative assets: Interest rate contracts $ 9 $ — $ 1 $ 13 $ (1 ) $ 22 Year Ended December 31, 2018 Equity securities $ — $ 44 $ — $ — $ (44 ) $ — Investment securities available-for-sale: State and municipal securities (c) 5 — — — (5 ) — Equity and other non-debt securities (c) 44 (44 ) — — — — Total investment securities 49 (44 ) — — (5 ) — Derivative assets: Interest rate contracts 14 — — (5 ) — 9 (a) Reflects the reclassification of equity securities resulting from the adoption of ASU 2016-01. (b) Realized and unrealized gains and losses due to changes in fair value recorded in other noninterest income on the Consolidated Statements of Income. (c) Auction-rate securities. Assets and Liabilities Recorded 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 December 31, 2019 and 2018 . No liabilities were recorded at fair value on a nonrecurring basis at December 31, 2019 and 2018 . (in millions) Level 3 December 31, 2019 Loans: Commercial $ 70 Total assets at fair value $ 70 December 31, 2018 Business loans: Commercial $ 96 Commercial mortgage 4 Total business loans 100 Retail loans: Residential mortgage 8 Total assets at fair value $ 108 Level 3 assets recorded at fair value on a nonrecurring basis at December 31, 2019 and 2018 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 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 — Customer 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 ) December 31, 2018 Assets Cash and due from banks $ 1,390 $ 1,390 $ 1,390 $ — $ — Interest-bearing deposits with banks 3,171 3,171 3,171 — — Loans held-for-sale 3 3 — 3 — Total loans, net of allowance for loan losses (a) 49,492 48,889 — — 48,889 Customers’ liability on acceptances outstanding 4 4 4 — — Restricted equity investments 248 248 248 — — Nonmarketable equity securities (b) 6 11 Liabilities Demand deposits (noninterest-bearing) 28,690 28,690 — 28,690 — Interest-bearing deposits 24,740 24,740 — 24,740 — Customer certificates of deposit 2,131 2,100 — 2,100 — Total deposits 55,561 55,530 — 55,530 — Short-term borrowings 44 44 44 — — Acceptances outstanding 4 4 4 — — Medium- and long-term debt 6,463 6,436 — 6,436 — Credit-related financial instruments (57 ) (57 ) — — (57 ) (a) Included $70 million and $108 million of impaired loans recorded at fair value on a nonrecurring basis at December 31, 2019 and 2018 , 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.

Investment Securities

Investment Securities	12 Months Ended
	Dec. 31, 2019
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 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 December 31, 2018 Investment securities available-for-sale: U.S. Treasury and other U.S. government agency securities $ 2,732 $ 14 $ 19 $ 2,727 Residential mortgage-backed securities (a) 9,493 22 197 9,318 Total investment securities available-for-sale $ 12,225 $ 36 $ 216 $ 12,045 (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 December 31, 2019 and 2018 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 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 December 31, 2018 U.S. Treasury and other U.S. government agency securities $ — $ — $ 1,457 $ 19 $ 1,457 $ 19 Residential mortgage-backed securities (a) 1,008 9 6,412 188 7,420 197 Total temporarily impaired securities $ 1,008 $ 9 $ 7,869 $ 207 $ 8,877 $ 216 (a) Issued and/or guaranteed by U.S. government agencies or U.S. government-sponsored enterprises. At December 31, 2019 , the Corporation had 170 residential mortgage-backed securities in an unrealized loss position with no credit impairment. The unrealized losses for these securities resulted from changes in market interest rates and liquidity, not changes in credit quality. The Corporation ultimately expects full collection of the carrying amount of these securities, does not intend to sell the securities in an unrealized loss position, and it is not more-likely-than-not that the Corporation will be required to sell the securities in an unrealized loss position prior to recovery of amortized cost. The Corporation does not consider these securities to be other-than-temporarily impaired at December 31, 2019 . Sales, primarily from repositioning $1.0 billion and $1.3 billion of lower-yielding treasury securities in the years ended December 31, 2019 and 2018 , respectively, of investment securities available-for-sale resulted in the following gains and losses recorded in net securities losses on the Consolidated Statements of Income, computed based on the adjusted cost of the specific security. There were no securities gains or losses for the year ended December 31, 2017 . (in millions) Year Ended December 31 2019 2018 Securities gains $ 1 $ 2 Securities losses (8 ) (21 ) Net securities losses $ (7 ) $ (19 ) 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) December 31, 2019 Amortized Cost Fair Value Contractual maturity Within one year $ 30 $ 30 After one year through five years 2,842 2,894 After five years through ten years 1,006 1,013 After ten years 8,435 8,461 Total investment securities $ 12,313 $ 12,398 Included in the contractual maturity distribution in the table above were residential mortgage-backed securities with a total amortized cost and fair value of $9.6 billion . The actual cash flows of mortgage-backed securities may differ from contractual maturity as the borrowers of the underlying loans may exercise prepayment options. At December 31, 2019 , investment securities with a carrying value of $518 million were pledged where permitted or required by law to secure $418 million of liabilities, primarily public and other deposits of state and local government agencies and derivative instruments.

Credit Quality And Allowance Fo

Credit Quality And Allowance For Credit Losses	12 Months Ended
	Dec. 31, 2019
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 recorded balance 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 Total Loans December 31, 2019 Business loans: Commercial $ 27 $ 7 $ 17 $ 51 $ 148 $ 31,274 $ 31,473 Real estate construction: Commercial Real Estate business line (a) 6 — — 6 — 3,038 3,044 Other business lines (b) — 7 — 7 — 404 411 Total real estate construction 6 7 — 13 — 3,442 3,455 Commercial mortgage: Commercial Real Estate business line (a) 9 — — 9 2 2,165 2,176 Other business lines (b) 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 December 31, 2018 Business loans: Commercial $ 34 $ 26 $ 8 $ 68 $ 141 $ 31,767 $ 31,976 Real estate construction: Commercial Real Estate business line (a) 6 — — 6 — 2,681 2,687 Other business lines (b) 6 — — 6 — 384 390 Total real estate construction 12 — — 12 — 3,065 3,077 Commercial mortgage: Commercial Real Estate business line (a) 4 — — 4 2 1,737 1,743 Other business lines (b) 32 5 8 45 18 7,300 7,363 Total commercial mortgage 36 5 8 49 20 9,037 9,106 Lease financing — — — — 2 505 507 International — — — — 3 1,010 1,013 Total business loans 82 31 16 129 166 45,384 45,679 Retail loans: Residential mortgage 11 3 — 14 36 1,920 1,970 Consumer: Home equity 4 1 — 5 19 1,741 1,765 Other consumer 1 — — 1 — 748 749 Total consumer 5 1 — 6 19 2,489 2,514 Total retail loans 16 4 — 20 55 4,409 4,484 Total loans $ 98 $ 35 $ 16 $ 149 $ 221 $ 49,793 $ 50,163 (a) Primarily loans to real estate developers. (b) Primarily loans secured by owner-occupied real estate. The following table presents loans by credit quality indicator, 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. Internally Assigned Rating (in millions) Pass (a) Special Mention (b) Substandard (c) Nonaccrual (d) Total December 31, 2019 Business loans: Commercial $ 29,785 $ 841 $ 699 $ 148 $ 31,473 Real estate construction: Commercial Real Estate business line (e) 3,013 19 12 — 3,044 Other business lines (f) 411 — — — 411 Total real estate construction 3,424 19 12 — 3,455 Commercial mortgage: Commercial Real Estate business line (e) 2,121 12 41 2 2,176 Other business lines (f) 7,141 147 83 12 7,383 Total commercial mortgage 9,262 159 124 14 9,559 Lease financing 579 7 2 — 588 International 972 29 8 — 1,009 Total business loans 44,022 1,055 845 162 46,084 Retail loans: Residential mortgage 1,823 2 — 20 1,845 Consumer: Home equity 1,682 1 11 17 1,711 Other consumer 722 6 1 — 729 Total consumer 2,404 7 12 17 2,440 Total retail loans 4,227 9 12 37 4,285 Total loans $ 48,249 $ 1,064 $ 857 $ 199 $ 50,369 December 31, 2018 Business loans: Commercial $ 30,817 $ 464 $ 554 $ 141 $ 31,976 Real estate construction: Commercial Real Estate business line (e) 2,664 23 — — 2,687 Other business lines (f) 382 8 — — 390 Total real estate construction 3,046 31 — — 3,077 Commercial mortgage: Commercial Real Estate business line (e) 1,682 14 45 2 1,743 Other business lines (f) 7,157 118 70 18 7,363 Total commercial mortgage 8,839 132 115 20 9,106 Lease financing 500 3 2 2 507 International 996 4 10 3 1,013 Total business loans 44,198 634 681 166 45,679 Retail loans: Residential mortgage 1,931 3 — 36 1,970 Consumer: Home equity 1,738 — 8 19 1,765 Other consumer 748 1 — — 749 Total consumer 2,486 1 8 19 2,514 Total retail loans 4,417 4 8 55 4,484 Total loans $ 48,615 $ 638 $ 689 $ 221 $ 50,163 (a) Includes all loans not included in the categories of special mention, substandard or nonaccrual. (b) Special mention loans are accruing loans that 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. This category is generally consistent with the "special mention" category as defined by regulatory authorities. (c) Substandard loans are accruing loans that 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 also are distinguished by the distinct possibility of loss in the future if these weaknesses are not corrected. This category is generally consistent with the "substandard" category as defined by regulatory authorities. (d) 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. A significant majority of nonaccrual loans are generally consistent with the "substandard" category and the remainder are generally consistent with the "doubtful" category as defined by regulatory authorities. (e) Primarily loans to real estate developers. (f) Primarily loans secured by owner-occupied real estate. The following table summarizes nonperforming assets. (in millions) December 31, 2019 December 31, 2018 Nonaccrual loans $ 199 $ 221 Reduced-rate loans (a) 5 8 Total nonperforming loans 204 229 Foreclosed property 11 1 Total nonperforming assets $ 215 $ 230 (a) Comprised of reduced-rate retail loans. There were no retail loans secured by residential real estate properties in process of foreclosure included in nonaccrual loans at December 31, 2019 , compared to $1 million at December 31, 2018 . Allowance for Credit Losses The following table details the changes in the allowance for loan losses and related loan amounts. 2019 2018 2017 (dollar amounts in millions) Business Loans Retail Loans Total Business Loans Retail Loans Total Business Loans Retail Loans Total Years Ended December 31 Allowance for loan losses: Balance at beginning of period $ 627 $ 44 $ 671 $ 661 $ 51 $ 712 $ 682 $ 48 $ 730 Loan charge-offs (147 ) (5 ) (152 ) (99 ) (4 ) (103 ) (143 ) (6 ) (149 ) Recoveries on loans previously charged-off 40 5 45 47 5 52 50 7 57 Net loan (charge-offs) recoveries (107 ) — (107 ) (52 ) 1 (51 ) (93 ) 1 (92 ) Provision for loan losses 81 (8 ) 73 19 (8 ) 11 71 2 73 Foreign currency translation adjustment — — — (1 ) — (1 ) 1 — 1 Balance at end of period $ 601 $ 36 $ 637 $ 627 $ 44 $ 671 $ 661 $ 51 $ 712 As a percentage of total loans 1.30 % 0.84 % 1.27 % 1.37 % 0.97 % 1.34 % 1.48 % 1.12 % 1.45 % December 31 Allowance for loan losses: Individually evaluated for impairment $ 31 $ — $ 31 $ 27 $ — $ 27 $ 67 $ — $ 67 Collectively evaluated for impairment 570 36 606 600 44 644 594 51 645 Total allowance for loan losses $ 601 $ 36 $ 637 $ 627 $ 44 $ 671 $ 661 $ 51 $ 712 Loans: Individually evaluated for impairment $ 199 $ 16 $ 215 $ 240 $ 36 $ 276 $ 443 $ 34 $ 477 Collectively evaluated for impairment 45,885 4,269 50,154 45,439 4,448 49,887 44,188 4,508 48,696 Total loans evaluated for impairment $ 46,084 $ 4,285 $ 50,369 $ 45,679 $ 4,484 $ 50,163 $ 44,631 $ 4,542 $ 49,173 Changes in the allowance for credit losses on lending-related commitments, included in accrued expenses and other liabilities on the Consolidated Balance Sheets, are summarized in the following table. (in millions) Years Ended December 31 2019 2018 2017 Balance at beginning of period $ 30 $ 42 $ 41 Provision for credit losses on lending-related commitments 1 (12 ) 1 Balance at end of period $ 31 $ 30 $ 42 Individually Evaluated Impaired Loans The following table presents additional information regarding individually evaluated impaired loans. Recorded Investment In: (in millions) Impaired Loans with No Related Allowance Impaired Loans with Related Allowance Total Impaired Loans Unpaid Principal Balance Related Allowance for Loan Losses December 31, 2019 Business loans: Commercial $ 30 $ 120 $ 150 $ 251 $ 30 Commercial mortgage: Commercial Real Estate business line (a) 39 — 39 49 — Other business lines (b) 1 9 10 15 1 Total commercial mortgage 40 9 49 64 1 Total business loans 70 129 199 315 31 Retail loans: Residential mortgage 8 — 8 8 — Consumer: Home equity 8 — 8 10 — Total retail loans (c) 16 — 16 18 — Total individually evaluated impaired loans $ 86 $ 129 $ 215 $ 333 $ 31 December 31, 2018 Business loans: Commercial $ 50 $ 130 $ 180 $ 227 $ 24 Commercial mortgage: Commercial Real Estate business line (a) 39 — 39 49 — Other business lines (b) 2 16 18 23 3 Total commercial mortgage 41 16 57 72 3 International 2 1 3 8 — Total business loans 93 147 240 307 27 Retail loans: Residential mortgage 16 8 24 25 — Consumer: Home equity 11 — 11 13 — Other consumer 1 — 1 1 — Total consumer 12 — 12 14 — Total retail loans (c) 28 8 36 39 — Total individually evaluated impaired loans $ 121 $ 155 $ 276 $ 346 $ 27 (a) Primarily loans to real estate developers. (b) Primarily loans secured by owner-occupied real estate. (c) Individually evaluated retail loans generally have no related allowance for loan losses, primarily due to policy which results in direct write-downs of most restructured retail loans. The following table presents information regarding average individually evaluated impaired loans and the related interest recognized. Interest income recognized for the period primarily related to performing restructured loans. Individually Evaluated Impaired Loans 2019 2018 2017 (in millions) Average Balance for the Period Interest Income Recognized for the Period Average Balance for the Period Interest Income Recognized for the Period Average Balance for the Period Interest Income Recognized for the Period Years Ended December 31 Business loans: Commercial $ 156 $ 2 $ 262 $ 5 $ 451 $ 8 Commercial mortgage: Commercial Real Estate business line (a) 39 3 40 4 21 2 Other business lines (b) 14 1 23 — 31 — Total commercial mortgage 53 4 63 4 52 2 Lease financing 1 — — — — — International 2 — 4 — 8 — Total business loans 212 6 329 9 511 10 Retail loans: Residential mortgage 21 1 21 — 24 — Consumer: Home equity 9 — 11 — 13 — Other consumer — — 1 — 3 — Total consumer 9 — 12 — 16 — Total retail loans 30 1 33 — 40 — Total individually evaluated impaired loans $ 242 $ 7 $ 362 $ 9 $ 551 $ 10 (a) Primarily loans to real estate developers. (b) Primarily loans secured by owner-occupied real estate. Troubled Debt Restructurings The following tables detail the recorded balance at December 31, 2019 and 2018 of loans considered to be TDRs that were restructured during the years ended December 31, 2019 and 2018 , 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. 2019 2018 Type of Modification Type of Modification (in millions) Principal Deferrals (a) Interest Rate Reductions Total Modifications Principal Deferrals (a) Interest Rate Reductions Total Modifications Years Ended December 31 Business loans: Commercial $ 28 $ — $ 28 $ 27 $ — $ 27 Commercial mortgage: Other business lines (b) — — — 2 — 2 International — — — 1 — 1 Total business loans 28 — 28 30 — 30 Retail loans: Consumer: Home equity (c) — 1 1 — 3 3 Total loans $ 28 $ 1 $ 29 $ 30 $ 3 $ 33 (a) Primarily represents loan balances where terms were extended 90 days or more at or above contractual interest rates. Also includes commercial loans restructured in bankruptcy. (b) Primarily loans secured by owner-occupied real estate. (c) Includes bankruptcy loans for which the court has discharged the borrower's obligation and the borrower has not reaffirmed the debt. The Corporation charges interest on principal balances outstanding during deferral periods. Additionally, none of the modifications involved forgiveness of principal. At December 31, 2019 and 2018 , commitments to lend additional funds to borrowers whose terms have been modified in TDRs totaled $3 million and $20 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 for each 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. Subsequent defaults of principal deferrals totaled $12 million in commercial loans for the year ended December 31, 2019 , compared to none in the comparable period in 2018 . There were no subsequent defaults of interest rate reductions during either of the years ended December 31, 2019 and 2018

Significant Group Concentration

Significant Group Concentrations of Credit Risk	12 Months Ended
	Dec. 31, 2019
Significant Group Concentrations of Credit Risk [Abstract]
Significant Group Concentrations of Credit Risk	SIGNIFICANT GROUP 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. Concentrations of both on-balance sheet and off-balance sheet credit risk are controlled and monitored as part of credit policies. The Corporation is a regional financial services holding company with a geographic concentration of its on-balance-sheet and off-balance-sheet activities in Michigan, California and Texas. As outlined below, the Corporation has a concentration of credit risk with the automotive industry. Loans to automotive dealers and to borrowers involved with automotive production are reported as automotive, as management believes these loans have similar economic characteristics that might cause them to react similarly to changes in economic conditions. This aggregation involves the exercise of judgment. Included in automotive production are: (a) original equipment manufacturers and Tier 1 and Tier 2 suppliers that produce components used in vehicles and whose primary revenue source is automotive-related (“primary” defined as greater than 50%) and (b) other manufacturers that produce components used in vehicles and whose primary revenue source is automotive-related. Loans less than $1 million and loans recorded in the Small Business loan portfolio were excluded from the definition. Outstanding loans, included in commercial loans on the Consolidated Balance Sheets, and total exposure (outstanding loans, unused commitments and standby letters of credit) to companies related to the automotive industry were as follows: (in millions) December 31 2019 2018 Automotive loans: Production $ 1,249 $ 1,331 Dealer 7,414 8,097 Total automotive loans $ 8,663 $ 9,428 Total automotive exposure: Production $ 2,358 $ 2,396 Dealer 9,677 10,044 Total automotive exposure $ 12,035 $ 12,440 Further, the Corporation’s portfolio of commercial real estate loans, which includes real estate construction and commercial mortgage loans, was as follows. (in millions) December 31 2019 2018 Real estate construction loans: Commercial Real Estate business line (a) $ 3,044 $ 2,687 Other business lines (b) 411 390 Total real estate construction loans 3,455 3,077 Commercial mortgage loans: Commercial Real Estate business line (a) 2,176 1,743 Other business lines (b) 7,383 7,363 Total commercial mortgage loans 9,559 9,106 Total commercial real estate loans $ 13,014 $ 12,183 Total unused commitments on commercial real estate loans $ 3,557 $ 3,146 (a) Primarily loans to real estate developers. (b) Primarily loans secured by owner-occupied real estate.

Premises and Equipment (Notes)

Premises and Equipment (Notes)	12 Months Ended
	Dec. 31, 2019
Premises and Equipments [Abstract]
Premises and Equipment	PREMISES AND EQUIPMENT A summary of premises and equipment by major category follows: (in millions) December 31 2019 2018 Land $ 86 $ 85 Buildings and improvements 818 842 Furniture and equipment 513 492 Total cost 1,417 1,419 Less: Accumulated depreciation and amortization (960 ) (944 ) Net book value $ 457 $ 475 The Corporation conducts a portion of its business from leased facilities and leases certain equipment. Rental expense for leased properties and equipment amounted to $81 million , $75 million and $78 million in 2019 , 2018 and 2017

Derivative And Credit-Related F

Derivative And Credit-Related Financial Instruments	12 Months Ended
	Dec. 31, 2019
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of Derivative 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 December 31, 2019 , counterparties with bilateral collateral agreements had no pledged marketable investment securities and deposited $12 million of cash with the Corporation to secure the fair value of contracts in an unrealized gain position, and the Corporation had pledged $23 million of marketable investment securities and posted $15 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 December 31, 2019 . 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 December 31, 2019 and 2018 . The table excludes commitments and warrants accounted for as derivatives. December 31, 2019 December 31, 2018 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 $ 3,325 $ — $ — $ 2,625 $ — $ 2 Swaps - cash flow - receive fixed/ pay floating 4,550 — — — — — Derivatives used as economic hedges Foreign exchange contracts: Spot, forwards and swaps 330 — 2 302 1 1 Total risk management purposes 8,205 — 2 2,927 1 3 Customer-initiated and other activities Interest rate contracts: Caps and floors written 671 — — 885 — 1 Caps and floors purchased 671 — — 885 1 — Swaps 16,485 211 39 13,115 66 67 Total interest rate contracts 17,827 211 39 14,885 67 68 Energy contracts: Caps and floors written 477 — 23 278 — 26 Caps and floors purchased 477 23 — 278 26 — Swaps 2,135 73 69 2,094 163 160 Total energy contracts 3,089 96 92 2,650 189 186 Foreign exchange contracts: Spot, forwards, options and swaps 1,013 10 8 1,095 18 12 Total customer-initiated and other activities 21,929 317 139 18,630 274 266 Total gross derivatives $ 30,134 317 141 $ 21,557 275 269 Amounts offset in the Consolidated Balance Sheets: Netting adjustment - Offsetting derivative assets/liabilities (63 ) (63 ) (45 ) (45 ) Netting adjustment - Cash collateral received/posted (11 ) (12 ) (174 ) (1 ) Net derivatives included in the Consolidated Balance Sheets (b) 243 66 56 223 Amounts not offset in the Consolidated Balance Sheets: Marketable securities pledged under bilateral collateral agreements — (21 ) (1 ) — Net derivatives after deducting amounts not offset in the Consolidated Balance Sheets $ 243 $ 45 $ 55 $ 223 (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 on 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 $9 million and $2 million at December 31, 2019 and 2018 , respectively. Risk Management The Corporation's derivative instruments used for managing interest rate risk include fair value hedging strategies that convert 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 Income. (in millions) Interest on Medium- and Long-Term Debt Years Ended December 31 2019 2018 Total interest on medium-and long-term debt (a) $ 197 $ 144 Fair value hedging relationships: Interest rate contracts: Hedged items 110 74 Derivatives designated as hedging instruments (4 ) (7 ) (a) Includes the effects of hedging. For the impact of cash flow hedging, refer to Note 14. 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 December 31, 2019 and 2018 . Weighted Average (dollar amounts in millions) Derivative Notional Amount Carrying Value of Hedged Items (a) Remaining Maturity (in years) Receive Rate Pay Rate (b) December 31, 2019 Swaps - cash flow - receive fixed/pay floating rate Variable rate loans $ 4,550 3.0 1.94 % 1.71 % Swaps - fair value - receive fixed/pay floating rate Medium- and long-term debt 3,325 $ 3,469 4.6 3.44 2.80 December 31, 2018 Swaps - fair value - receive fixed/pay floating rate Medium- and long-term debt 2,625 2,663 3.9 3.40 3.45 (a) Included $146 million and $49 million of cumulative hedging adjustments at December 31, 2019 and 2018 , respectively, which included $7 million and $8 million , respectively, of hedging adjustment on a discontinued hedging relationship. (b) Variable rates paid on receive fixed swaps designated as fair value and cash flow hedges are based on one- and six-month LIBOR rates in effect at December 31, 2019 and 2018 . 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 on the Consolidated Statements of 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 net gains and losses in other noninterest income on the Consolidated Statements of Income for the years ended December 31, 2019 and 2018 , respectively. Fair values of customer-initiated and other derivative instruments represent the net unrealized gains or losses on such contracts and are recorded on the Consolidated Balance Sheets. Changes in fair value are recognized on the Consolidated Statements of Income. The net gains recognized in income on customer-initiated derivative instruments, net of the impact of offsetting positions, were as follows: (in millions) Years Ended December 31 Location of Gain 2019 2018 Interest rate contracts Other noninterest income $ 29 $ 26 Energy contracts Other noninterest income 5 4 Foreign exchange contracts Foreign exchange income 43 47 Total $ 77 $ 77 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) December 31 2019 2018 Unused commitments to extend credit: Commercial and other $ 23,681 $ 24,266 Bankcard, revolving check credit and home equity loan commitments 3,180 3,001 Total unused commitments to extend credit $ 26,861 $ 27,267 Standby letters of credit $ 3,320 $ 3,244 Commercial letters of credit 18 39 The Corporation maintains an allowance to cover probable credit losses inherent in 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 $31 million and $30 million at December 31, 2019 and 2018 , 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 $25 million and $24 million at December 31, 2019 and 2018 , respectively, for probable credit losses inherent in 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 $161 million and $136 million at December 31, 2019 and 2018 , respectively, of the $3.3 billion of standby and commercial letters of credit outstanding at both December 31, 2019 and 2018 . 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 $32 million at December 31, 2019 , including $26 million in deferred fees and $6 million in the allowance for credit losses on lending-related commitments. At December 31, 2018 , the comparable amounts were $34 million , $28 million and $6 million , respectively. The following table presents a summary of criticized standby and commercial letters of credit at December 31, 2019 and 2018 . The Corporation's criticized list is 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) December 31, 2019 December 31, 2018 Total criticized standby and commercial letters of credit $ 44 $ 49 As a percentage of total outstanding standby and commercial letters of credit 1.3 % 1.5 % 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 agreement for such borrowers. The Corporation manages its credit risk on the credit risk participation agreements by monitoring the creditworthiness of the borrowers, which is based on the normal credit review process had it entered into the derivative instruments directly with the borrower. The notional amount of such credit risk participation agreement reflects the pro-rata share of the derivative instrument, consistent with its share of the related participated loan. As of December 31, 2019 and 2018 , the total notional amount of the credit risk participation agreements was approximately $786 million and $703 million , respectively, and the fair value was insignificant for both periods. 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 $20 million and $7 million at December 31, 2019 and 2018 , 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 December 31, 2019 , the weighted average remaining maturity of outstanding credit risk participation agreements was 3.4 years.

Goodwill and Intangible Assets

Goodwill and Intangible Assets	12 Months Ended
	Dec. 31, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Core Deposit Intangibles	GOODWILL AND CORE DEPOSIT INTANGIBLES The following table summarizes the carrying value of goodwill by reporting unit for the years ended December 31, 2019 and 2018 . (in millions) December 31 2019 2018 Business Bank $ 473 $ 473 Retail Bank 101 101 Wealth Management 61 61 Total $ 635 $ 635 The Corporation performs its annual evaluation of goodwill impairment in the third quarter of each year and on an interim basis if events or changes in circumstances between annual tests indicate goodwill might be impaired. In 2019 and 2018 , the annual test of goodwill impairment was performed as of the beginning of the third quarter, and in both of these periods, a qualitative assessment resulted in the Corporation determining goodwill was not impaired as it was more likely than not the fair value of each reporting unit exceeded its carrying value. A summary of core deposit intangible carrying value and related accumulated amortization follows: (in millions) December 31 2019 2018 Gross carrying amount $ 34 $ 34 Accumulated amortization (32 ) (30 ) Net carrying amount $ 2 $ 4 The Corporation recorded amortization expense related to the core deposit intangible of $2 million for both the years ended December 31, 2019 and 2018 . At December 31, 2019 , estimated future amortization expense was as follows: (in millions) Years Ending December 31 2020 $ 1 2021 1 Total $ 2

Net Income Per Common Share

Net Income Per Common Share	12 Months Ended
	Dec. 31, 2019
Earnings Per Share [Abstract]
Net Income Per Common Share	NET INCOME PER COMMON SHARE Basic and diluted net income per common share are presented in the following table. (in millions, except per share data) Years Ended December 31 2019 2018 2017 Basic and diluted Net income $ 1,198 $ 1,235 $ 743 Less: Income allocated to participating securities 7 8 5 Net income attributable to common shares $ 1,191 $ 1,227 $ 738 Basic average common shares 150 168 174 Basic net income per common share $ 7.95 $ 7.31 $ 4.23 Basic average common shares 150 168 174 Dilutive common stock equivalents: Net effect of the assumed exercise of stock options 1 2 3 Net effect of the assumed exercise of warrants — 1 1 Diluted average common shares 151 171 178 Diluted net income per common share $ 7.87 $ 7.20 $ 4.14 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. There were no anti-dilutive options for the year ended December 31, 2017. Years Ended December 31 2019 2018 Average outstanding options 542,786 193,248 Range of exercise prices $67.53 - $95.25 $95.25

Variable Interest Entities (VIE

Variable Interest Entities (VIEs)	12 Months Ended
	Dec. 31, 2019
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 December 31, 2019 was limited to $441 million and $6 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 ( $160 million at December 31, 2019 ). 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 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 years ended December 31, 2019 , 2018 and 2017 . The following table summarizes the impact of these tax credit entities on line items on the Corporation’s Consolidated Statements of Income. (in millions) Years Ended December 31 2019 2018 2017 Other noninterest income: Sales of other tax credit investments $ 2 $ 5 $ 2 Provision for income taxes: Amortization of LIHTC Investments 65 65 67 Low income housing tax credits (62 ) (62 ) (63 ) Other tax benefits related to tax credit entities (13 ) (14 ) (24 ) Total provision for income taxes $ (10 ) $ (11 ) $ (20 ) For further information on the Corporation’s consolidation policy, see Note 1.

Deposits

Deposits	12 Months Ended
	Dec. 31, 2019
Deposits [Abstract]
Deposits	DEPOSITS At December 31, 2019 , the scheduled maturities of certificates of deposit and other deposits with a stated maturity were as follows: (in millions) Years Ending December 31 2020 $ 2,970 2021 156 2022 24 2023 15 2024 11 Thereafter 26 Total $ 3,202 A maturity distribution of domestic certificates of deposit of $100,000 and over follows: (in millions) December 31 2019 2018 Three months or less $ 398 $ 363 Over three months to six months 503 146 Over six months to twelve months 819 278 Over twelve months 97 297 Total $ 1,817 $ 1,084 The aggregate amount of domestic certificates of deposit that meet or exceed the current FDIC insurance limit of $250,000 was $956 million and $543 million at December 31, 2019 and 2018 , respectively. All foreign office time deposits of $91 million and $8 million at December 31, 2019 and 2018 , respectively, were in denominations of $250,000 or more.

Short-term Borrowings

Short-term Borrowings	12 Months Ended
	Dec. 31, 2019
Short-term Debt [Abstract]
Short-term Borrowings	SHORT-TERM BORROWINGS Federal funds purchased and securities sold under agreements to repurchase generally mature within one to four days from the transaction date. Other short-term borrowings, which may consist of borrowed securities and short-term notes, generally mature within one to 120 days from the transaction date. At December 31, 2019 , Comerica Bank (the Bank), a wholly-owned subsidiary of the Corporation, had pledged loans totaling $22.0 billion which provided for up to $17.8 billion of available collateralized borrowing with the FRB. The following table provides a summary of short-term borrowings. (dollar amounts in millions) Federal Funds Purchased and Securities Sold Under Agreements to Repurchase Other Short-term Borrowings December 31, 2019 Amount outstanding at year-end $ 71 $ — Weighted average interest rate at year-end 1.50 % — % Maximum month-end balance during the year $ 835 $ 1,200 Average balance outstanding during the year 113 256 Weighted average interest rate during the year 2.28 % 2.44 % December 31, 2018 Amount outstanding at year-end $ 44 $ — Weighted average interest rate at year-end 2.39 % — % Maximum month-end balance during the year $ 182 $ 250 Average balance outstanding during the year 59 3 Weighted average interest rate during the year 1.91 % 1.75 % December 31, 2017 Amount outstanding at year-end $ 10 $ — Weighted average interest rate at year-end 1.43 % — % Maximum month-end balance during the year $ 41 $ 1,024 Average balance outstanding during the year 20 257 Weighted average interest rate during the year 1.02 % 1.15 %

Medium- And Long-Term Debt

Medium- And Long-Term Debt	12 Months Ended
	Dec. 31, 2019
Debt Disclosure [Abstract]
Medium- And Long-Term Debt	MEDIUM- AND LONG-TERM DEBT Medium- and long-term debt is summarized as follows: (in millions) December 31 2019 2018 Parent company Subordinated notes: 3.80% subordinated notes due 2026 (a) $ 264 $ 250 Medium- and long-term notes: 2.125% notes due 2019 (a) — 348 3.70% notes due 2023 (a) 884 861 4.00% notes due 2029 (a) 587 — Total medium- and long-term notes 1,471 1,209 Total parent company 1,735 1,459 Subsidiaries Subordinated notes: 4.00% subordinated notes due 2025 (a) 360 343 7.875% subordinated notes due 2026 (a) 202 198 Total subordinated notes 562 541 Medium- and long-term notes: 2.50% notes due 2020 (a) 674 663 2.50% notes due 2024 (a) 498 — Total medium- and long-term notes 1,172 663 Federal Home Loan Bank (FHLB) advances: Floating-rate based on FHLB auction rate due 2026 2,800 2,800 Floating-rate based on FHLB auction rate due 2028 1,000 1,000 Total FHLB advances 3,800 3,800 Total subsidiaries 5,534 5,004 Total medium- and long-term debt $ 7,269 $ 6,463 (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. 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 rate on the FHLB advances resets between four and eight weeks, based on the FHLB auction rate. At December 31, 2019 , the weighted-average rate on the FHLB advances was 1.75% . Each note may be prepaid in full, without penalty, at each scheduled reset date. Borrowing capacity is contingent upon the amount of collateral available to be pledged to the FHLB. At December 31, 2019 , $17.2 billion of real estate-related loans were pledged to the FHLB as blanket collateral for current and potential future borrowings of approximately $5.1 billion . The Corporation issued $350 million of 4.00% senior notes maturing in 2029, swapped to a floating rate at 30-day LIBOR plus 129 basis points in first quarter 2019 and issued an additional $200 million of 4.00% senior notes maturing in 2029 in third quarter 2019, swapped to a floating rate at 30-day LIBOR plus 123 basis points. These notes were consolidated under a single series with an aggregate principal amount of $550 million. Also in third quarter 2019, the Bank issued $500 million of 2.50% medium-term notes due in 2024, swapped to a floating rate based on 30-day LIBOR plus 84 basis points. Unamortized debt issuance costs deducted from the carrying amount of medium- and long-term debt totaled $12 million and $8 million at December 31, 2019 and 2018 , respectively. At December 31, 2019 , the principal maturities of medium- and long-term debt were as follows: (in millions) Years Ending December 31 2020 $ 675 2021 — 2022 — 2023 850 2024 500 Thereafter 5,100 Total $ 7,125

Shareholders' Equity

Shareholders' Equity	12 Months Ended
	Dec. 31, 2019
Stockholders' Equity Note [Abstract]
Stockholders' Equity	SHAREHOLDERS’ EQUITY Repurchases of common stock under the equity repurchase program initially authorized in 2010 by the Board of Directors of the Corporation totaled 18.6 million shares at an average price paid of $73.60 in 2019 , 14.8 million shares at an average price paid of $89.21 per share in 2018 and 7.3 million shares at an average price paid of $72.44 per share in 2017 . There is no expiration date for the Corporation's equity repurchase program. During the year ended December 31, 2019 , the Corporation repurchased $1.4 billion under the equity repurchase program. At December 31, 2019 , the Corporation had no outstanding warrants as all remaining warrants to purchase common stock expired in 2018 . Approximately 585,000 and 1.8 million shares of common stock were issued upon exercise of warrants in 2018 and 2017 , respectively. At December 31, 2019 , the Corporation had 3.8 million shares of common stock reserved for stock option exercises and restricted stock unit vesting and 458,000 shares of restricted stock outstanding to employees and directors under share-based compensation plans.

Accumulated Other Comprehensive

Accumulated Other Comprehensive Loss	12 Months Ended
	Dec. 31, 2019
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Accumulated Other Comprehensive Income (Loss)	ACCUMULATED OTHER COMPREHENSIVE LOSS The following table presents a reconciliation of the changes in the components of accumulated other comprehensive loss and details the components of other comprehensive income (loss) for the years ended December 31, 2019 , 2018 and 2017 , including the amount of income tax expense (benefit) allocated to each component of other comprehensive income (loss). (in millions) Years Ended December 31 2019 2018 2017 Accumulated net unrealized gains (losses) on investment securities: Balance at beginning of period, net of tax $ (138 ) $ (101 ) $ (33 ) Cumulative effect of change in accounting principle — 1 — Net unrealized holding gains (losses) arising during the period 257 (69 ) (81 ) Less: Provision (benefit) for income taxes 60 (16 ) (27 ) Net unrealized holding gains (losses) arising during the period, net of tax 197 (53 ) (54 ) Less: Net realized losses included in net securities losses (8 ) (20 ) — Less: Benefit for income taxes (2 ) (5 ) — Reclassification adjustment for net securities losses included in net income, net of tax (6 ) (15 ) — Less: Net losses realized as a yield adjustment in interest on investment securities — — (3 ) Less: Benefit for income taxes — — (1 ) Reclassification adjustment for net losses realized as a yield adjustment included in net income, net of tax — — (2 ) Change in net unrealized gains (losses) on investment securities, net of tax 203 (38 ) (52 ) Reclassification of certain deferred tax effects (a) — — (16 ) Balance at end of period, net of tax $ 65 $ (138 ) $ (101 ) Accumulated net gains on cash flow hedges: Balance at beginning of period, net of tax $ — $ — $ — Net cash flow hedge gains arising during the period 44 — — Less: Provision for income taxes 10 — — Change in net cash flow hedge gains, net of tax 34 — — Balance at end of period, net of tax (b) $ 34 $ — $ — Accumulated defined benefit pension and other postretirement plans adjustment: Balance at beginning of period, net of tax $ (471 ) $ (350 ) $ (350 ) Actuarial gain (loss) arising during the period 163 (191 ) 72 Less: Provision (benefit) for income taxes 38 (44 ) 17 Net defined benefit pension and other postretirement adjustment arising during the period, net of tax 125 (147 ) 55 Amounts recognized in other noninterest expense: Amortization of actuarial net loss 42 61 51 Amortization of prior service credit (27 ) (27 ) (27 ) Total amounts recognized in other noninterest expense 15 34 24 Less: Provision for income taxes 3 8 8 Adjustment for amounts recognized as other components of net benefit cost during the period, net of tax 12 26 16 Change in defined benefit pension and other postretirement plans adjustment, net of tax 137 (121 ) 71 Reclassification of certain deferred tax effects (a) — — (71 ) Balance at end of period, net of tax $ (334 ) $ (471 ) $ (350 ) Total accumulated other comprehensive loss at end of period, net of tax $ (235 ) $ (609 ) $ (451 ) (a) Amounts reclassified to retained earnings due to early adoption of ASU 2018-02. For further information, refer to Note 1. (b) The corporation expects to reclassify $12 million of net gains, net of tax, from accumulated other comprehensive loss to earnings over the next twelve months if interest yield curves and notional amounts remain at December 31, 2019 levels.

Share-Based Compensation

Share-Based Compensation	12 Months Ended
	Dec. 31, 2019
Share-based Payment Arrangement, Noncash Expense [Abstract]
Share-based Compensation	SHARE-BASED COMPENSATION Share-based compensation expense is charged to salaries and benefits expense on the Consolidated Statements of Income. The components of share-based compensation expense for all share-based compensation plans and related tax benefits are as follows: (in millions) Years Ended December 31 2019 2018 2017 Total share-based compensation expense $ 39 $ 48 $ 39 Related tax benefits recognized in net income $ 9 $ 11 $ 14 The following table summarizes unrecognized compensation expense for all share-based plans. (dollar amounts in millions) December 31, 2019 Total unrecognized share-based compensation expense $ 33 Weighted-average expected recognition period (in years) 2.3 The Corporation has share-based compensation plans under which it awards shares of restricted stock units to executive officers, directors and key personnel, and stock options to executive officers and key personnel of the Corporation and its subsidiaries. Additionally, the Corporation has awarded restricted stock to executive officers and key personnel under a previous share-based compensation plan that remain unvested. Restricted stock and restricted stock units fully vest after a period ranging from three years to five years, and stock options fully vest after four years. The maturity of each option is determined at the date of grant; however, no options may be exercised later than ten years from the date of grant. The options may have restrictions regarding exercisability. The plans provide for a grant of up to 6.1 million common shares, plus shares under certain plans that are forfeited, expire or are canceled, which become available for re-grant. At December 31, 2019 , over 5 million shares were available for grant. The Corporation used a binomial model to value stock options granted in the periods presented. Option valuation models require several inputs, including the expected stock price volatility, and changes in input assumptions can materially affect the fair value estimates. The model used may not necessarily provide a reliable single measure of the fair value of stock options. The risk-free interest rate assumption used in the binomial option-pricing model as outlined in the table below was based on the federal ten-year treasury interest rate. The expected dividend yield was based on the historical and projected long-term dividend yield patterns of the Corporation’s common shares. Expected volatility assumptions considered both the historical volatility of the Corporation’s common stock over a ten-year period and implied volatility based on actively traded options on the Corporation’s common stock with pricing terms and trade dates similar to the stock options granted. Expected option life was based on historical exercise activity over the contractual term of the option grant (10 years), excluding certain forced transactions. The estimated weighted-average grant-date fair value per option and the underlying binomial option-pricing model assumptions are summarized in the following table: Years Ended December 31 2019 2018 2017 Weighted-average grant-date fair value per option $ 22.27 $ 30.32 $ 19.61 Weighted-average assumptions: Risk-free interest rates 2.74 % 2.63 % 2.47 % Expected dividend yield 3.00 3.00 3.00 Expected volatility factors of the market price of Comerica common stock 30 36 34 Expected option life (in years) 7.6 7.4 7.0 A summary of the Corporation’s stock option activity and related information for the year ended December 31, 2019 follows: Weighted-Average Number of Options (in thousands) Exercise Price per Share Remaining Contractual Term (in years) Aggregate Intrinsic Value (in millions) Outstanding-January 1, 2019 2,943 $ 44.70 Granted 283 80.14 Forfeited or expired (35 ) 65.91 Exercised (511 ) 37.32 Outstanding-December 31, 2019 2,680 49.58 5.3 $ 66 Exercisable-December 31, 2019 1,816 $ 41.79 4.2 $ 56 The aggregate intrinsic value of outstanding options shown in the table above represents the total pretax intrinsic value at December 31, 2019 , based on the Corporation’s closing stock price of $71.75 at December 31, 2019 . The total intrinsic value of stock options exercised was $20 million , $81 million and $104 million for the years ended December 31, 2019 , 2018 and 2017 , respectively. A summary of the Corporation’s restricted stock activity and related information for the year ended December 31, 2019 follows: Number of Shares (in thousands) Weighted-Average Grant-Date Fair Value per Share Outstanding-January 1, 2019 869 $ 44.34 Forfeited (27 ) 49.81 Vested (384 ) 38.81 Outstanding-December 31, 2019 458 $ 48.64 The total fair value of restricted stock awards that fully vested was $15 million , $14 million and $19 million for the years ended December 31, 2019 , 2018 and 2017 , respectively. A summary of the Corporation's restricted stock unit activity and related information for the year ended December 31, 2019 follows: Service-Based Units Performance-Based Units Number of Units (in thousands) Weighted-Average Grant-Date Fair Value per Share Number of Units (in thousands) Weighted-Average Grant-Date Fair Value per Share Outstanding-January 1, 2019 367 $ 68.14 662 $ 56.64 Granted 237 78.81 329 66.80 Forfeited (14 ) 87.38 (28 ) 81.06 Vested (12 ) 55.81 (420 ) 32.53 Outstanding-December 31, 2019 578 72.34 543 80.22 The total fair value of restricted stock units that fully vested was $14 million , $10 million and $10 million for the years ended December 31, 2019 , 2018 and 2017 , respectively. The Corporation expects to satisfy the exercise of stock options, the vesting of restricted stock units and future grants of restricted stock by issuing shares of common stock out of treasury. At December 31, 2019 , the Corporation held 86.1 million shares in treasury. For further information on the Corporation’s share-based compensation plans, refer to Note 1 .

Employee Benefit Plans

Employee Benefit Plans	12 Months Ended
	Dec. 31, 2019
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Abstract]
Employee Benefit Plans	EMPLOYEE BENEFIT PLANS Defined Benefit Pension and Postretirement Benefit Plans The Corporation has a qualified and non-qualified defined benefit pension plan. In October 2016, the Corporation modified its defined benefit pension plans to freeze final average pay benefits as of December 31, 2016, other than for participants who were age 60 or older as of December 31, 2016, and added a cash balance plan provision effective January 1, 2017. Active pension plan participants 60 years or older as of December 31, 2016 receive the greater of the final average pay formula or the frozen final average pay benefit as of December 31, 2016 plus the cash balance benefit earned after January 1, 2017. Employees participating in the retirement account plan as of December 31, 2016 were eligible to participate in the cash balance pension plan effective January 1, 2017. Benefits earned under the cash balance pension formula, in the form of an account balance, include contribution credits based on eligible pay earned each month, age and years of service and monthly interest credits based on the 30-year Treasury rate. The Corporation’s postretirement benefit plan provides postretirement health care and life insurance benefits for retirees as of December 31, 1992. The plan also provides certain postretirement health care and life insurance benefits for a limited number of retirees who retired prior to January 1, 2000. For all other employees hired prior to January 1, 2000, a nominal benefit is provided. Employees hired on or after January 1, 2000 and prior to January 1, 2007 are eligible to participate in the plan on a full contributory basis until Medicare-eligible based on age and service. Employees hired on or after January 1, 2007 are not eligible to participate in the plan. The Corporation funds the pre-1992 retiree plan benefits with bank-owned life insurance. The following table sets forth reconciliations of plan assets and the projected benefit obligation, the weighted-average assumptions used to determine year-end benefit obligations, and the amounts recognized in accumulated other comprehensive income (loss) for the Corporation’s defined benefit pension plans and postretirement benefit plan at December 31, 2019 and 2018 . The Corporation used a measurement date of December 31, 2019 for these plans. Defined Benefit Pension Plans Qualified Non-Qualified Postretirement Benefit Plan (dollar amounts in millions) 2019 2018 2019 2018 2019 2018 Change in fair value of plan assets: Fair value of plan assets at January 1 $ 2,458 $ 2,747 $ — $ — $ 56 $ 60 Actual return on plan assets 579 (167 ) — — 5 (1 ) Employer contributions — — — — 1 1 Benefits paid (104 ) (122 ) — — (5 ) (4 ) Fair value of plan assets at December 31 $ 2,933 $ 2,458 $ — $ — $ 57 $ 56 Change in projected benefit obligation: Projected benefit obligation at January 1 $ 1,901 $ 2,061 $ 211 $ 212 $ 46 $ 51 Service cost 31 29 3 2 — — Interest cost 80 75 9 8 2 2 Actuarial loss (gain) 223 (142 ) 25 — 5 (3 ) Benefits paid (104 ) (122 ) (13 ) (11 ) (5 ) (4 ) Projected benefit obligation at December 31 $ 2,131 $ 1,901 $ 235 $ 211 $ 48 $ 46 Accumulated benefit obligation $ 2,121 $ 1,893 $ 234 $ 209 $ 48 $ 46 Funded status at December 31 (a) (b) $ 802 $ 557 $ (235 ) $ (211 ) $ 9 $ 10 Weighted-average assumptions used: Discount rate 3.43 % 4.37 % 3.43 % 4.37 % 3.26 % 4.26 % Rate of compensation increase 4.00 4.00 4.00 4.00 n/a n/a Healthcare cost trend rate: Cost trend rate assumed for next year n/a n/a n/a n/a 6.25 6.50 Rate to which the cost trend rate is assumed to decline (the ultimate trend rate) n/a n/a n/a n/a 4.50 4.50 Year when rate reaches the ultimate trend rate n/a n/a n/a n/a 2027 2027 Amounts recognized in accumulated other comprehensive income (loss) before income taxes: Net actuarial loss $ (463 ) $ (687 ) $ (94 ) $ (76 ) $ (20 ) $ (19 ) Prior service credit 121 140 26 34 1 1 Balance at December 31 $ (342 ) $ (547 ) $ (68 ) $ (42 ) $ (19 ) $ (18 ) (a) Based on projected benefit obligation for defined benefit pension plans and accumulated benefit obligation for postretirement benefit plan. (b) The Corporation recognizes the overfunded and underfunded status of the plans in accrued income and other assets and accrued expenses and other liabilities, respectively, on the Consolidated Balance Sheets. n/a - not applicable Because the non-qualified defined benefit pension plan has no assets, the accumulated benefit obligation exceeded the fair value of plan assets at December 31, 2019 and December 31, 2018 . The following table details the changes in plan assets and benefit obligations recognized in other comprehensive income (loss) for the year ended December 31, 2019 . Defined Benefit Pension Plans (in millions) Qualified Non-Qualified Postretirement Benefit Plan Total Actuarial gain (loss) arising during the period $ 190 $ (25 ) $ (2 ) $ 163 Amortization of net actuarial loss 34 7 1 42 Amortization of prior service credit (19 ) (8 ) — (27 ) Total recognized in other comprehensive income (loss) $ 205 $ (26 ) $ (1 ) $ 178 Components of net periodic defined benefit cost and postretirement benefit cost, the actual return on plan assets and the weighted-average assumptions used were as follows: Defined Benefit Pension Plans (dollar amounts in millions) Qualified Non-Qualified Years Ended December 31 2019 2018 2017 2019 2018 2017 Service cost (a) $ 31 $ 29 $ 29 $ 3 $ 2 $ 2 Other components of net benefit (credit) cost: Interest cost 80 75 78 9 8 8 Expected return on plan assets (166 ) (165 ) (159 ) — — — Amortization of prior service credit (19 ) (19 ) (19 ) (8 ) (8 ) (8 ) Amortization of net loss 34 51 43 7 9 8 Total other components of net benefit (credit) cost (b) (71 ) (58 ) (57 ) 8 9 8 Net periodic defined benefit (credit) cost $ (40 ) $ (29 ) $ (28 ) $ 11 $ 11 $ 10 Actual return on plan assets $ 579 $ (167 ) $ 396 n/a n/a n/a Actual rate of return on plan assets 24.07 % (6.21 )% 16.48 % n/a n/a n/a Weighted-average assumptions used: Discount rate 4.37 % 3.74 % 4.23 % 4.37 % 3.74 % 4.23 % Expected long-term return on plan assets 6.50 6.50 6.50 n/a n/a n/a Rate of compensation increase 4.00 3.75 3.50 4.00 3.75 3.50 (a) Included in salaries and benefits expense on the Consolidated Statements of Income. (b) Included in other noninterest expenses on the Consolidated Statements of Income. n/a - not applicable (dollar amounts in millions) Postretirement Benefit Plan Years Ended December 31 2019 2018 2017 Other components of net benefit cost: Interest cost $ 2 $ 2 $ 2 Expected return on plan assets (3 ) (3 ) (3 ) Amortization of net loss 1 1 1 Net periodic postretirement benefit cost $ — $ — $ — Actual return on plan assets $ 5 $ (1 ) $ 2 Actual rate of return on plan assets 9.14 % (2.05 )% 3.52 % Weighted-average assumptions used: Discount rate 4.26 % 3.55 % 3.92 % Expected long-term return on plan assets 5.00 5.00 5.00 Healthcare cost trend rate: Cost trend rate assumed 6.50 6.50 6.50 Rate to which the cost trend rate is assumed to decline (the ultimate trend rate) 4.50 4.50 4.50 Year that the rate reaches the ultimate trend rate 2027 2027 2027 The expected long-term rate of return of plan assets is the average rate of return expected to be realized on funds invested or expected to be invested over the life of the plan, which has an estimated duration of approximately 12 years as of December 31, 2019 . The expected long-term rate of return on plan assets is set after considering both long-term returns in the general market and long-term returns experienced by the assets in the plan. The returns on the various asset categories are blended to derive one long-term rate of return. The Corporation reviews its pension plan assumptions on an annual basis with its actuarial consultants to determine if assumptions are reasonable and adjusts the assumptions to reflect changes in future expectations. The estimated portion of balances remaining in accumulated other comprehensive income (loss) that are expected to be recognized as a component of net periodic benefit cost in the year ended December 31, 2020 are as follows: Defined Benefit Pension Plans (in millions) Qualified Non-Qualified Postretirement Benefit Plan Total Net loss $ 54 $ 9 $ 1 $ 64 Prior service credit (19 ) (8 ) — (27 ) Assumed healthcare cost trend rates have a significant effect on the amounts reported for the postretirement benefit plan. A one-percentage-point change in 2019 assumed healthcare and prescription drug cost trend rates would result in a five -percentage-point change in the postretirement benefit obligation. Plan Assets The Corporation’s overall investment goals for the qualified defined benefit pension plan are to maintain a portfolio of assets of appropriate liquidity and diversification; to generate investment returns (net of operating costs) that are reasonably anticipated to maintain the plan’s fully funded status or to reduce a funding deficit, after taking into account various factors, including reasonably anticipated future contributions and expense and the interest rate sensitivity of the plan’s assets relative to that of the plan’s liabilities; and to generate investment returns (net of operating costs) that meet or exceed a customized benchmark as defined in the plan investment policy. Derivative instruments are permissible for hedging and transactional efficiency, but only to the extent that the derivative use enhances the efficient execution of the plan’s investment policy. The plan does not directly invest in securities issued by the Corporation and its subsidiaries. The Corporation’s target allocations for plan investments are 45 percent to 55 percent for both equity securities and fixed income, including cash. Equity securities include collective investment and mutual funds and common stock. Fixed income securities include U.S. Treasury and other U.S. government agency securities, mortgage-backed securities, corporate bonds and notes, municipal bonds, collateralized mortgage obligations and money market funds. Fair Value Measurements The Corporation’s qualified defined benefit pension plan utilizes fair value measurements to record fair value adjustments and to determine fair value disclosures. The Corporation’s qualified benefit pension plan categorizes investments recorded at fair value into a three-level hierarchy, based on the markets in which the investment are traded and the reliability of the assumptions used to determine fair value. Refer to Note 1 for a description of the three-level hierarchy. Following is a description of the valuation methodologies and key inputs used to measure the fair value of the Corporation’s qualified defined benefit pension plan investments, including an indication of the level of the fair value hierarchy in which the investments are classified. Mutual funds Fair value measurement is based upon the net asset value (NAV) provided by the administrator of the fund. Mutual fund NAVs are quoted in an active market exchange, such as the New York Stock Exchange, and are included in Level 1 of the fair value hierarchy. Common stock Fair value measurement is based upon the closing price quoted in an active market exchange, such as the New York Stock Exchange. Level 1 common stock includes domestic and foreign stock and real estate investment trusts. U.S. Treasury and other U.S. government agency securities Level 1 securities include U.S. Treasury securities that are traded by dealers or brokers in active over-the-counter markets. Fair value measurement is based upon quoted prices in an active market exchange, such as the New York Stock Exchange. Level 2 securities include debt securities issued by U.S. government agencies and U.S. government-sponsored entities. The fair value of Level 2 securities is determined using quoted prices of securities with similar characteristics, or pricing models based on observable market data inputs, primarily interest rates and spreads. Corporate and municipal bonds and notes Fair value measurement is based upon quoted prices of securities with similar characteristics or pricing models based on observable market data inputs, primarily interest rates, spreads and prepayment information. Level 2 securities include corporate bonds, municipal bonds, foreign bonds and foreign notes. Mortgage-backed securities Fair value measurement is based upon independent pricing models or other model-based valuation techniques such as the present value of future cash flows, adjusted for the security's credit rating, prepayment assumptions and other factors, such as credit loss and liquidity assumptions, and are included in Level 2 of the fair value hierarchy. Private placements Fair value is measured using the NAV provided by fund management as quoted prices in active markets are not available. Management considers additional discounts to the provided NAV for market and credit risk. Private placements are included in Level 3 of the fair value hierarchy. Collective investment funds Fair value measurement is based upon the NAV provided by the administrator of the fund as a practical expedient to estimate fair value. There are no unfunded commitments or redemption restrictions on the collective investment funds. The investments are redeemable daily. Fair Values The fair values of the Corporation’s qualified defined benefit pension plan investments measured at fair value on a recurring basis at December 31, 2019 and 2018 , by asset category and level within the fair value hierarchy, are detailed in the table below. (in millions) Total Level 1 Level 2 Level 3 December 31, 2019 Equity securities: Mutual funds $ 2 $ 2 $ — $ — Common stock 1,086 1,086 — — Fixed income securities: U.S. Treasury and other U.S. government agency securities 574 551 23 — Corporate and municipal bonds and notes 734 — 734 — Mortgage-backed securities 27 — 27 — Private placements 57 — — 57 Total investments in the fair value hierarchy 2,480 $ 1,639 $ 784 $ 57 Investments measured at net asset value: Collective investment funds 469 Total investments at fair value $ 2,949 December 31, 2018 Equity securities: Mutual funds $ 3 $ 3 $ — $ — Common stock 803 803 — — Fixed income securities: U.S. Treasury and other U.S. government agency securities 496 482 14 — Corporate and municipal bonds and notes 679 — 679 — Mortgage-backed securities 29 — 29 — Private placements 60 — — 60 Total investments in the fair value hierarchy 2,070 $ 1,288 $ 722 $ 60 Investments measured at net asset value: Collective investment funds 392 Total investments at fair value $ 2,462 The table below provides a summary of changes in the Corporation’s qualified defined benefit pension plan’s Level 3 investments measured at fair value on a recurring basis for the years ended December 31, 2019 and 2018 . Balance at Beginning of Period Balance at End of Period Net Gains (Losses) (in millions) Realized Unrealized Purchases Sales Year Ended December 31, 2019 Private placements $ 60 $ 3 $ 8 $ 49 $ (63 ) $ 57 Year Ended December 31, 2018 Private placements $ 80 $ (1 ) $ (7 ) $ 70 $ (82 ) $ 60 There were no assets in the non-qualified defined benefit pension plan at December 31, 2019 and 2018 . The postretirement benefit plan is fully invested in bank-owned life insurance policies. The fair value of bank-owned life insurance policies is based on the cash surrender values of the policies as reported by the insurance companies and is classified in Level 2 of the fair value hierarchy. Cash Flows The Corporation currently expects to make no employer contributions to the qualified and non-qualified defined benefit pension plans and postretirement benefit plan for the year ended December 31, 2020 . Estimated Future Benefit Payments (in millions) Years Ended December 31 Qualified Defined Benefit Pension Plan Non-Qualified Defined Benefit Pension Plan Postretirement Benefit Plan (a) 2020 $ 134 $ 14 $ 5 2021 133 14 5 2022 136 14 5 2023 137 15 5 2024 139 15 4 2025 - 2029 683 74 16 (a) Estimated benefit payments in the postretirement benefit plan are net of estimated Medicare subsidies. Defined Contribution Plans Substantially all of the Corporation’s employees are eligible to participate in the Corporation’s principal defined contribution plan (a 401(k) plan). Under this plan, the Corporation makes core matching cash contributions of 100 percent of the first 4 percent of qualified earnings contributed by employees (up to the current IRS compensation limit), invested based on employee investment elections. Employee benefits expense included expense for the plan of $22 million for the year ended December 31, 2019 , and $21 million for the years ended December 31, 2018 and 2017 . Deferred Compensation Plans The Corporation offers optional deferred compensation plans under which certain employees and non-employee directors (participants) may make an irrevocable election to defer incentive compensation and/or a portion of base salary until retirement or separation from the Corporation. The participant may direct deferred compensation into one or more deemed investment options. Although not required to do so, the Corporation invests actual funds into the deemed investments as directed by participants, resulting in a deferred compensation asset, recorded in other short-term investments on the Consolidated Balance Sheets that offsets the liability to participants under the plan, recorded in accrued expenses and other liabilities. The earnings from the deferred compensation asset are recorded in interest on short-term investments and other noninterest income and the related change in the liability to participants under the plan is recorded in salaries and benefits expense on the Consolidated Statements of Income.

Income Taxes And Tax-Related It

Income Taxes And Tax-Related Items	12 Months Ended
	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Income Taxes and Tax-Related Items	INCOME TAXES AND TAX-RELATED ITEMS The provision for income taxes is calculated as the sum of income taxes due for the current year and deferred taxes. Income taxes due for the current year is computed by applying federal and state tax statutes to current year taxable income. Deferred taxes arise from temporary differences between the income tax basis and financial accounting basis of assets and liabilities. Tax-related interest and penalties and foreign taxes are then added to the tax provision. The current and deferred components of the provision for income taxes were as follows: (in millions) December 31 2019 2018 2017 Current: Federal $ 267 $ 227 $ 371 Foreign 7 10 5 State and local 48 39 36 Total current 322 276 412 Deferred: Federal 16 29 (26 ) State and local (4 ) 3 (2 ) Remeasurement of deferred taxes — (8 ) 107 Total deferred 12 24 79 Total $ 334 $ 300 $ 491 Income before income taxes of $1.5 billion for the year ended December 31, 2019 included $42 million of foreign-source income. The Tax Cuts and Jobs Act (the "Act"), enacted on December 22, 2017, reduced the U.S. federal corporate tax rate from 35 percent to 21 percent. The amount recorded related to the remeasurement of the Corporation’s deferred tax balance was a reduction of $99 million , including a provisional adjustment of $107 million recognized in 2017 and an $8 million revision to the impact recorded in 2018. The provision for income taxes does not reflect the tax effects of unrealized gains and losses on investment securities available-for-sale or the change in defined benefit pension and other postretirement plans adjustment included in accumulated other comprehensive loss. Refer to Note 14 for additional information on accumulated other comprehensive loss. A reconciliation of expected income tax expense at the federal statutory rate to the Corporation’s provision for income taxes and effective tax rate follows: (dollar amounts in millions) 2019 2018 2017 Years Ended December 31 Amount Rate Amount Rate Amount Rate Tax based on federal statutory rate $ 322 21.0 % $ 323 21.0 % $ 432 35.0 % State income taxes 33 2.2 35 2.3 22 1.8 Employee stock transactions (12 ) (0.8 ) (23 ) (1.5 ) (35 ) (2.8 ) Capitalization and recovery positions (a) — — (17 ) (1.1 ) — — Affordable housing and historic credits (11 ) (0.7 ) (12 ) (0.8 ) (21 ) (1.7 ) Bank-owned life insurance (9 ) (0.6 ) (9 ) (0.6 ) (16 ) (1.3 ) Remeasurement of deferred taxes — — (8 ) (0.5 ) 107 8.7 FDIC insurance expense (b) 5 0.3 8 0.5 — — Other changes in unrecognized tax benefits — — 4 0.3 — — Tax-related interest and penalties 2 0.1 (3 ) (0.2 ) 4 0.3 Lease termination transactions — — — — (2 ) (0.2 ) Other 4 0.2 2 0.1 — — Provision for income taxes $ 334 21.7 % $ 300 19.5 % $ 491 39.8 % (a) Tax benefits from the review of tax capitalization and recovery positions related to software and fixed assets included in the 2017 tax return. (b) Beginning January 1, 2018, FDIC insurance expense is no longer deductible as a result of the enactment of the Tax Cuts and Jobs Act. The liability for tax-related interest and penalties included in accrued expenses and other liabilities on the Consolidated Balance Sheets was $8 million and $7 million at December 31, 2019 and 2018 , respectively. 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) may review and/or challenge specific interpretive tax positions taken by the Corporation with respect to those transactions. The Corporation believes that 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. A reconciliation of the beginning and ending amount of net unrecognized tax benefits follows: (in millions) 2019 2018 2017 Balance at January 1 $ 14 $ 10 $ 15 Increase as a result of tax positions taken during a prior period 4 9 4 Decrease related to settlements with tax authorities (1 ) (4 ) (8 ) Other — (1 ) (1 ) Balance at December 31 $ 17 $ 14 $ 10 The Corporation anticipates it is reasonably possible settlements with tax authorities will result in a $5 million decrease in net unrecognized tax benefits within the next twelve months. After consideration of the effect of the federal tax benefit available on unrecognized state tax benefits, the total amount of unrecognized tax benefits, if recognized, would affect the Corporation’s effective tax rate was approximately $14 million and $11 million at December 31, 2019 and 2018 , respectively. The following tax years for significant jurisdictions remain subject to examination as of December 31, 2019 : Jurisdiction Tax Years Federal 2014-2018 California 2006-2017 Based on current knowledge and probability assessment of various potential outcomes, the Corporation believes 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. The principal components of deferred tax assets and liabilities were as follows: (in millions) December 31 2019 2018 Deferred tax assets: Allowance for loan losses $ 134 $ 141 Deferred compensation 61 68 Deferred loan origination fees and costs 8 9 Net unrealized losses on investment securities available-for-sale — 42 Operating lease liability 77 — Other temporary differences, net 49 42 Total deferred tax asset before valuation allowance 329 302 Valuation allowance (3 ) (3 ) Total deferred tax assets 326 299 Deferred tax liabilities: Lease financing transactions (73 ) (74 ) Defined benefit plans (91 ) (41 ) Allowance for depreciation (21 ) (18 ) Hedging gains and losses (10 ) — Leasing right of use asset (69 ) — Net unrealized gains on investment securities available-for-sale (20 ) — Total deferred tax liabilities (284 ) (133 ) Net deferred tax asset $ 42 $ 166 Deferred tax assets included state net operating loss carryforwards of $3 million and $4 million at December 31, 2019 and December 31, 2018 , respectively, which expire between 2019 and 2028 . The Corporation believes it is more likely than not 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 December 31, 2019 and December 31, 2018 . For further information on the Corporation’s valuation policy for deferred tax assets, refer to Note 1

Transactions with Related Parti

Transactions with Related Parties	12 Months Ended
	Dec. 31, 2019
Related Party Transactions [Abstract]
Transactions with Related Parties	TRANSACTIONS WITH RELATED PARTIES The Corporation’s banking subsidiaries had, and expect to have in the future, transactions with the Corporation’s directors and executive officers, companies with which these individuals are associated, and certain related individuals. Such transactions were made in the ordinary course of business and included extensions of credit, leases and professional services. With respect to extensions of credit, all were made on substantially the same terms, including interest rates and collateral, as those prevailing at the same time for comparable transactions with other customers and did not, in management’s opinion, involve more than normal risk of collectibility or present other unfavorable features. The aggregate amount of loans attributable to persons who were related parties at December 31, 2019 , totaled $109 million at the beginning of 2019 and $74 million at the end of 2019 . During 2019 , new loans to related parties aggregated $732 million and repayments totaled $767 million .

Regulatory Capital and Reserve

Regulatory Capital and Reserve Requirements	12 Months Ended
	Dec. 31, 2019
Broker-Dealer, Net Capital Requirement, SEC Regulation [Abstract]
Regulatory Capital and Reserve Requirements	REGULATORY CAPITAL AND RESERVE REQUIREMENTS Reserves required to be maintained and/or deposited with the FRB are classified in interest-bearing deposits with banks. These reserve balances vary, depending on the level of customer deposits in the Corporation’s banking subsidiaries. The average required reserve balances were $586 million and $599 million for the years ended December 31, 2019 and 2018 , respectively. Banking regulations limit the transfer of assets in the form of dividends, loans or advances from the bank subsidiaries to the parent company. Under the most restrictive of these regulations, the aggregate amount of dividends which can be paid to the parent company, with prior approval from bank regulatory agencies, approximated $98 million at January 1, 2020 , plus 2020 net profits. Substantially all the assets of the Corporation’s banking subsidiaries are restricted from transfer to the parent company of the Corporation in the form of loans or advances. The Corporation’s subsidiary banks declared dividends of $1.2 billion , $1.1 billion and $907 million in 2019 , 2018 and 2017 , respectively. The Corporation and its U.S. banking subsidiaries are subject to various regulatory capital requirements administered by federal and state banking agencies under the Basel III regulatory framework (Basel III). This regulatory framework establishes comprehensive methodologies for calculating regulatory capital and risk-weighted assets (RWA). Basel III also set minimum capital ratios as well as overall capital adequacy standards. Under Basel III, regulatory capital comprises common equity Tier 1 (CET1) capital, additional Tier 1 capital and Tier II capital. CET1 capital predominantly includes common shareholders' equity, less certain deductions for goodwill, intangible assets and deferred tax assets that arise from net operating losses and tax credit carry-forwards. Additionally, the Corporation has elected to permanently exclude capital in accumulated other comprehensive income (AOCI) related to debt and equity securities classified as available-for-sale as well as for cash flow hedges and defined benefit postretirement plans from CET1, an option available to standardized approach entities under Basel III. Tier 1 capital incrementally includes noncumulative perpetual preferred stock. Tier 2 capital includes Tier 1 capital as well as subordinated debt qualifying as Tier 2 and qualifying allowance for credit losses. In addition to the minimum risk-based capital requirements, the Corporation and its Bank subsidiaries are required to maintain a minimum capital conservation buffer, in the form of common equity, of 2.5 percent in order to avoid restrictions on capital distributions and discretionary bonuses. The Corporation computes RWA using the standardized approach. Under the standardized approach, RWA is generally based on supervisory risk-weightings which vary by counterparty type and asset class. Under the Basel III standardized approach, capital is required for credit risk RWA, to cover the risk of unexpected losses due to failure of a customer or counterparty to meet its financial obligations in accordance with contractual terms; and if trading assets and liabilities exceed certain thresholds, capital is also required for market risk RWA, to cover the risk of losses due to adverse market movements or from position-specific factors. Quantitative measures established by regulation to ensure capital adequacy require the maintenance of minimum amounts and ratios of CET1, Tier 1 and total capital (as defined in the regulations) to average and/or risk-weighted assets. Failure to meet minimum capital requirements can initiate certain mandatory and possibly additional discretionary actions by regulators that, if undertaken, could have a direct material effect on the Corporation’s financial statements. At December 31, 2019 and 2018 , the Corporation and its U.S. banking subsidiaries exceeded the ratios required for an institution to be considered “well capitalized” For U.S. banking subsidiaries, those requirements were total risk-based capital, Tier 1 risk-based capital, CET1 risk-based capital and leverage ratios greater than 10 percent , 8 percent , 6.5 percent and 5 percent , respectively, at December 31, 2019 and 2018 . For the Corporation, requirements to be considered "well capitalized" were total risk-based capital and Tier 1 risk-based capital ratios greater than 10 percent and 6 percent , respectively, at December 31, 2019 and 2018 . There have been no conditions or events since December 31, 2019 that management believes have changed the capital adequacy classification of the Corporation or its U.S. banking subsidiaries. The following is a summary of the capital position of the Corporation and Comerica Bank, its principal banking subsidiary. (dollar amounts in millions) Comerica Incorporated (Consolidated) Comerica Bank December 31, 2019 CET1 capital (minimum $3.1 billion (Consolidated)) $ 6,919 $ 7,199 Tier 1 capital (minimum $4.1 billion (Consolidated)) 6,919 7,199 Total capital (minimum $5.5 billion (Consolidated)) 8,282 8,371 Risk-weighted assets 68,273 68,071 Average assets (fourth quarter) 72,773 72,564 CET1 capital to risk-weighted assets (minimum-4.5%) 10.13 % 10.58 % Tier 1 capital to risk-weighted assets (minimum-6.0%) 10.13 10.58 Total capital to risk-weighted assets (minimum-8.0%) 12.13 12.30 Tier 1 capital to average assets (minimum-4.0%) 9.51 9.92 Capital conservation buffer (minimum-2.5%) 4.13 4.30 December 31, 2018 CET1 capital (minimum $3.0 billion (Consolidated)) $ 7,470 $ 7,229 Tier 1 capital (minimum $4.0 billion (Consolidated)) 7,470 7,229 Total capital (minimum $5.4 billion (Consolidated)) 8,855 8,433 Risk-weighted assets 67,047 66,857 Average assets (fourth quarter) 71,070 70,905 CET1 capital to risk-weighted assets (minimum-4.5%) 11.14 % 10.81 % Tier 1 capital to risk-weighted assets (minimum-6.0%) 11.14 10.81 Total capital to risk-weighted assets (minimum-8.0%) 13.21 12.61 Tier 1 capital to average assets (minimum-4.0%) 10.51 10.20 Capital conservation buffer (minimum-2.5%) 5.14 4.61

Contingent Liabilities

Contingent Liabilities	12 Months Ended
	Dec. 31, 2019
Commitments and Contingencies Disclosure [Abstract]
Contingent Liabilities	CONTINGENT LIABILITIES Legal Proceedings 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. The court also heard argument on whether Masters is entitled to attorneys fees, and if so how much. Its decision is pending. The Bank is considering its options, including additional appeals. Management believes that current reserves related to this case are adequate in the event of a negative 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 $15 million , $17 million and $15 million for the years ended December 31, 2019 , 2018 and 2017 , respectively, were included in other noninterest expenses on the Consolidated Statements of Income. 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 $45 million at December 31, 2019 . 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 that 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 18 .

Business Segment Information

Business Segment Information	12 Months Ended
	Dec. 31, 2019
Segment Reporting [Abstract]
Business Segment Information	BUSINESS SEGMENT INFORMATION The Corporation has strategically aligned its operations into three major business segments: the Business 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 December 31, 2019 . 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) funding credits and charges. 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. This credit or charge is based on matching stated or implied maturities for these assets and liabilities. The FTP crediting rates on deposits and other funds provided reflect the long-term value of deposits and other funding sources based on their implied maturity. 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. For acquired loans and deposits, matched maturity funding is determined based on origination date. Accordingly, the FTP process reflects the transfer of interest rate risk exposures to the Corporate Treasury department within the Finance segment, where such exposures are centrally managed. Effective January 1, 2019, the Corporation prospectively discontinued allocating an additional FTP charge for the cost of maintaining liquid assets to support potential draws on unfunded loan commitments. The allowance for loan losses is allocated to the business segments based on the methodology used to estimate the consolidated allowance for loan losses described in Note 1 . The related provision for loan losses is assigned based on the amount necessary to maintain an allowance for loan losses appropriate for each business segment. Noninterest income and expenses directly attributable to a line of business are assigned to that business segment. Direct expenses incurred by areas whose services support the overall Corporation are allocated to the business segments as follows: product processing expenditures are allocated based on standard unit costs applied to actual volume measurements; administrative expenses are allocated based on estimated time expended; and corporate overhead is assigned 50 percent based on the ratio of the business segment’s noninterest expenses to total noninterest expenses incurred by all business segments and 50 percent based on the ratio of the business segment’s attributed equity to total attributed equity of all business segments. Equity is attributed based on credit, operational and interest rate risks. Most of the equity attributed relates to credit risk, which is determined based on the credit score and expected remaining life of each loan, letter of credit and unused commitment recorded in the business segments. Operational risk is allocated based on loans and letters of credit, deposit balances, non-earning assets, trust assets under management, certain noninterest income items, and the nature and extent of expenses incurred by business units. Virtually all interest rate risk is assigned to Finance, as are the Corporation’s hedging activities. The following discussion provides information about the activities of each business segment. A discussion of the financial results and the factors impacting 2019 performance can be found in the section entitled "Business Segments" in the financial review. The Business 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. Business segment financial results are as follows: (dollar amounts in millions) Business Bank Retail Bank Wealth Management Finance Other Total Year Ended December 31, 2019 Earnings summary: Net interest income (expense) $ 1,655 $ 568 $ 183 $ (126 ) $ 59 $ 2,339 Provision for credit losses 88 (4 ) (14 ) — 4 74 Noninterest income 555 132 270 43 10 1,010 Noninterest expenses 795 597 283 (1 ) 69 1,743 Provision (benefit) for income taxes 306 24 44 (26 ) (14 ) (a) 334 Net income (loss) $ 1,021 $ 83 $ 140 $ (56 ) $ 10 $ 1,198 Net credit-related charge-offs (recoveries) $ 111 $ 1 $ (5 ) $ — $ — $ 107 Selected average balances: Assets $ 44,946 $ 2,852 $ 5,083 $ 14,235 $ 4,372 $ 71,488 Loans 43,472 2,104 4,935 — — 50,511 Deposits 29,047 20,743 3,833 1,673 185 55,481 Statistical data: Return on average assets (b) 2.27 % 0.39 % 2.76 % n/m n/m 1.68 % Efficiency ratio (c) 35.96 84.49 62.45 n/m n/m 51.82 Year Ended December 31, 2018 Earnings summary: Net interest income (expense) $ 1,613 $ 548 $ 181 $ (46 ) $ 56 $ 2,352 Provision for credit losses 6 (1 ) (3 ) — (3 ) (1 ) Noninterest income 547 136 266 27 — 976 Noninterest expenses 847 602 293 (4 ) 56 1,794 Provision (benefit) for income taxes 283 18 36 (14 ) (23 ) (a) 300 Net income (loss) $ 1,024 $ 65 $ 121 $ (1 ) $ 26 $ 1,235 Net credit-related charge-offs (recoveries) $ 52 $ — $ (1 ) $ — $ — $ 51 Selected average balances: Assets $ 43,207 $ 2,633 $ 5,214 $ 13,705 $ 5,965 $ 70,724 Loans 41,618 2,067 5,081 — — 48,766 Deposits 30,116 20,812 3,941 941 125 55,935 Statistical data: Return on average assets (b) 2.37 % 0.31 % 2.32 % n/m n/m 1.75 % Efficiency ratio (c) 39.22 87.59 65.60 n/m n/m 53.56 (Table continues on following page) (dollar amounts in millions) Business Bank Retail Bank Wealth Management Finance Other Total Year Ended December 31, 2017 Earnings summary: Net interest income (expense) $ 1,513 $ 453 $ 169 $ (111 ) $ 37 $ 2,061 Provision for credit losses 69 2 1 — 2 74 Noninterest income 639 154 255 49 10 1,107 Noninterest expenses 918 615 285 (4 ) 46 1,860 Provision (benefit) for income taxes 410 (4 ) 51 (35 ) 69 (a) 491 Net income (loss) $ 755 $ (6 ) $ 87 $ (23 ) $ (70 ) $ 743 Net credit-related charge-offs (recoveries) $ 96 $ 1 $ (5 ) $ — $ — $ 92 Selected average balances: Assets $ 42,653 $ 2,626 $ 5,401 $ 13,954 $ 6,818 $ 71,452 Loans 41,241 2,061 5,256 — — 48,558 Deposits 31,999 20,775 4,081 241 162 57,258 Statistical data: Return on average assets (b) 1.77 % (0.03 )% 1.61 % n/m n/m 1.04 % Efficiency ratio (c) 42.67 101.29 67.06 n/m n/m 58.70 (a) Primarily reflected discrete tax items, including benefits of $17 million and $48 million in 2019 and 2018 , respectively, and a net charge of $72 million in 2017 . (b) Return on average assets is calculated based on the greater of average assets or average liabilities and attributed equity. (c) 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 December 31, 2019 . 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: (dollar amounts in millions) Michigan California Texas Other Markets Finance & Other Total Year Ended December 31, 2019 Earnings summary: Net interest income (expense) $ 729 $ 811 $ 493 $ 373 $ (67 ) $ 2,339 Provision for credit losses (11 ) (33 ) 119 (5 ) 4 74 Noninterest income 291 173 128 365 53 1,010 Noninterest expenses 554 406 345 369 69 1,743 Provision (benefit) for income taxes 108 155 38 74 (41 ) (a) 334 Net income (loss) $ 369 $ 456 $ 119 $ 300 $ (46 ) $ 1,198 Net credit-related charge-offs (recoveries) $ 11 $ 8 $ 93 $ (5 ) $ — $ 107 Selected average balances: Assets $ 13,157 $ 18,856 $ 11,269 $ 9,599 $ 18,607 $ 71,488 Loans 12,553 18,540 10,616 8,802 — 50,511 Deposits 20,081 16,857 8,780 7,905 1,858 55,481 Statistical data: Return on average assets (b) 1.77 % 2.42 % 1.06 % 3.13 % n/m 1.68 % Efficiency ratio (c) 54.02 41.21 55.59 50.03 n/m 51.82 (Table continues on following page) (dollar amounts in millions) Michigan California Texas Other Markets Finance & Other Total Year Ended December 31, 2018 Earnings summary: Net interest income $ 727 $ 788 $ 474 $ 353 $ 10 $ 2,352 Provision for credit losses 30 26 (53 ) (1 ) (3 ) (1 ) Noninterest income 296 164 130 359 27 976 Noninterest expenses 577 424 365 376 52 1,794 Provision (benefit) for income taxes 90 123 64 60 (37 ) (a) 300 Net income $ 326 $ 379 $ 228 $ 277 $ 25 $ 1,235 Net credit-related charge-offs $ 7 $ 27 $ 12 $ 5 $ — $ 51 Selected average balances: Assets $ 13,207 $ 18,544 $ 10,380 $ 8,922 $ 19,671 $ 70,724 Loans 12,531 18,283 9,812 8,140 — 48,766 Deposits 20,770 16,964 8,992 8,144 1,065 55,935 Statistical data: Return on average assets (b) 1.51 % 2.04 % 2.20 % 3.11 % n/m 1.75 % Efficiency ratio (c) 56.22 44.58 60.30 52.93 n/m 53.56 Year Ended December 31, 2017 Earnings summary: Net interest income (expense) $ 657 $ 711 $ 451 $ 316 $ (74 ) $ 2,061 Provision for credit losses 8 101 (72 ) 36 1 74 Noninterest income 324 171 131 423 58 1,107 Noninterest expenses 589 404 375 450 42 1,860 Provision for income taxes 137 145 104 71 34 (a) 491 Net income (loss) $ 247 $ 232 $ 175 $ 182 $ (93 ) $ 743 Net credit-related (recoveries) charge-offs $ (1 ) $ 33 $ 46 $ 14 $ — $ 92 Selected average balances: Assets $ 13,393 $ 18,269 $ 10,434 $ 8,584 $ 20,772 $ 71,452 Loans 12,676 18,008 9,960 7,914 — 48,558 Deposits 21,818 17,533 9,623 7,881 403 57,258 Statistical data: Return on average assets (b) 1.09 % 1.25 % 1.61 % 2.12 % n/m 1.04 % Efficiency ratio (c) 60.01 45.83 64.35 60.98 n/m 58.70 (a) Primarily reflected discrete tax items, including benefits of $17 million and $48 million in 2019 and 2018 , respectively, and a net charge of $72 million in 2017 . (b) Return on average assets is calculated based on the greater of average assets or average liabilities and attributed equity. (c) 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

Parent Company FInancial Statem

Parent Company FInancial Statements	12 Months Ended
	Dec. 31, 2019
Condensed Financial Information Disclosure [Abstract]
Parent Company Financial Statments	PARENT COMPANY FINANCIAL STATEMENTS BALANCE SHEETS - COMERICA INCORPORATED (in millions, except share data) December 31 2019 2018 Assets Cash and due from subsidiary bank $ 1,196 $ 1,524 Other short-term investments 95 88 Investment in subsidiaries, principally banks 7,784 7,429 Premises and equipment 1 1 Other assets 242 169 Total assets $ 9,318 $ 9,211 Liabilities and Shareholders’ Equity Medium- and long-term debt $ 1,735 $ 1,459 Other liabilities 256 245 Total liabilities 1,991 1,704 Common stock - $5 par value: Authorized - 325,000,000 shares Issued - 228,164,824 shares 1,141 1,141 Capital surplus 2,174 2,148 Accumulated other comprehensive loss (235 ) (609 ) Retained earnings 9,538 8,781 Less cost of common stock in treasury - 86,069,234 shares at 12/31/19 and 68,081,176 shares at 12/31/18 (5,291 ) (3,954 ) Total shareholders’ equity 7,327 7,507 Total liabilities and shareholders’ equity $ 9,318 $ 9,211 STATEMENTS OF INCOME - COMERICA INCORPORATED (in millions) Years Ended December 31 2019 2018 2017 Income Income from subsidiaries: Dividends from subsidiaries $ 1,229 $ 1,135 $ 915 Other interest income 20 13 3 Intercompany management fees 224 228 136 Other noninterest income — — 8 Total income 1,473 1,376 1,062 Expenses Interest on medium- and long-term debt 56 29 13 Salaries and benefits expense 143 140 127 Occupancy expense 6 5 5 Equipment expense 1 1 1 Restructuring charges — 2 6 Other noninterest expenses 72 75 80 Total expenses 278 252 232 Income before benefit for income taxes and equity in undistributed earnings of subsidiaries 1,195 1,124 830 Benefit for income taxes (9 ) (5 ) (26 ) Income before equity in undistributed earnings of subsidiaries 1,204 1,129 856 Equity in undistributed earnings of subsidiaries, principally banks (6 ) 106 (113 ) Net income 1,198 1,235 743 Less income allocated to participating securities 7 8 5 Net income attributable to common shares $ 1,191 $ 1,227 $ 738 STATEMENTS OF CASH FLOWS - COMERICA INCORPORATED (in millions) Years Ended December 31 2019 2018 2017 Operating Activities Net income $ 1,198 $ 1,235 $ 743 Adjustments to reconcile net income to net cash provided by operating activities: Undistributed earnings of subsidiaries, principally banks 6 (106 ) 113 Depreciation and amortization 1 1 1 Net periodic defined benefit cost (credit) 4 4 (2 ) Share-based compensation expense 15 21 16 Benefit for deferred income taxes (2 ) (1 ) (10 ) Other, net 28 10 59 Net cash provided by operating activities 1,250 1,164 920 Financing Activities Medium- and long-term debt: Maturities (350 ) — — Issuances 550 850 — Common Stock: Repurchases (1,394 ) (1,338 ) (560 ) Cash dividends paid (402 ) (263 ) (180 ) Issuances of common stock under employee stock plans 18 52 118 Net cash used in financing activities (1,578 ) (699 ) (622 ) Net (decrease) increase in cash and cash equivalents (328 ) 465 298 Cash and cash equivalents at beginning of period 1,524 1,059 761 Cash and cash equivalents at end of period $ 1,196 $ 1,524 $ 1,059 Interest paid $ 55 $ 11 $ 12 Income taxes recovered $ (226 ) $ (155 ) $ (331 )

Summary of Quarterly Financial

Summary of Quarterly Financial Statements (Unaudited)	12 Months Ended
	Dec. 31, 2019
Quarterly Financial Information Disclosure [Abstract]
Summary of Quarterly Financial Statements (Unaudited)	SUMMARY OF QUARTERLY FINANCIAL STATEMENTS (UNAUDITED) The following quarterly information is unaudited. However, in the opinion of management, the information reflects all adjustments, which are necessary for the fair presentation of the results of operations, for the periods presented. 2019 (in millions, except per share data) Fourth Quarter Third Quarter Second Quarter First Quarter Interest income $ 659 $ 711 $ 727 $ 710 Interest expense 115 125 124 104 Net interest income 544 586 603 606 Provision for credit losses 8 35 44 (13 ) Net securities gains (losses) 1 — — (8 ) Noninterest income excluding net securities gains (losses) 265 256 250 246 Noninterest expenses 451 435 424 433 Provision for income taxes 82 80 87 85 Net income 269 292 298 339 Less income allocated to participating securities 2 2 1 2 Net income attributable to common shares $ 267 $ 290 $ 297 $ 337 Earnings per common share: Basic $ 1.87 $ 1.98 $ 1.95 $ 2.14 Diluted 1.85 1.96 1.94 2.11 Comprehensive income 370 338 429 435 2018 (in millions, except per share data) Fourth Quarter Third Quarter Second Quarter First Quarter Interest income $ 704 $ 675 $ 650 $ 590 Interest expense 90 76 60 41 Net interest income 614 599 590 549 Provision for credit losses 16 — (29 ) 12 Net securities (losses) gains — (20 ) — 1 Noninterest income excluding net securities (losses) gains 250 254 248 243 Noninterest expenses 448 452 448 446 Provision for income taxes 90 63 93 54 Net income 310 318 326 281 Less income allocated to participating securities 2 2 2 2 Net income attributable to common shares $ 308 $ 316 $ 324 $ 279 Earnings per common share: Basic $ 1.91 $ 1.89 $ 1.90 $ 1.62 Diluted 1.88 1.86 1.87 1.59 Comprehensive income 312 296 290 178

Revenue from Contracts with Cus

Revenue from Contracts with Customers Revenue from Contracts with Customers	12 Months Ended
	Dec. 31, 2019
Revenue from Contracts with Customers [Abstract]
Revenue from Contract with Customer	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. Business Bank Retail Bank Wealth Management Finance & Other Total (in millions) Year Ended December 31, 2019 Revenue from contracts with customers: Card fees $ 213 $ 40 $ 4 $ — $ 257 Fiduciary income — — 206 — 206 Service charges on deposit accounts 130 68 5 — 203 Commercial loan servicing fees (a) 18 — — — 18 Brokerage fees — — 28 — 28 Other noninterest income (b) 8 11 18 — 37 Total revenue from contracts with customers 369 119 261 — 749 Other sources of noninterest income 186 13 9 53 261 Total noninterest income $ 555 $ 132 $ 270 $ 53 $ 1,010 Year Ended December 31, 2018 Revenue from contracts with customers: Card fees (c) $ 201 $ 39 $ 4 $ — $ 244 Fiduciary income — — 206 — 206 Service charges on deposit accounts (c) 134 72 5 — 211 Commercial loan servicing fees (a) 18 — — — 18 Brokerage fees — — 27 — 27 Other noninterest income (b) 12 19 17 1 49 Total revenue from contracts with customers 365 130 259 1 755 Other sources of noninterest income 182 6 7 26 221 Total noninterest income $ 547 $ 136 $ 266 $ 27 $ 976 Year Ended December 31, 2017 Card fees $ 285 $ 43 $ 5 $ — $ 333 Fiduciary income — — 198 — 198 Services charges on deposit accounts 143 79 5 — 227 Commercial lending fees 84 — 1 — 85 Letter of credit fees 44 — 1 — 45 Bank-owned life insurance — — — 43 43 Foreign exchange income 43 — 2 — 45 Brokerage fees — — 23 — 23 Other noninterest income 40 32 20 16 108 Total noninterest income $ 639 $ 154 $ 255 $ 59 $ 1,107 (a) Included in commercial lending fees on the Consolidated Statements of Income. (b) Excludes derivative, warrant and other miscellaneous income. (c) Adoption of Topic 606 resulted in a change in presentation which records certain costs in the same category as the associated revenues. The effect of this change was to reduce card fees by $140 million and service charges on deposit accounts by $5 million for the twelve months ended December 31, 2018. Refer to Note 1 for further information. Adjustments to revenue during the years ended December 31, 2019 and 2018 for refunds or credits relating to prior periods were not significant. Revenue from contracts with customers did not generate significant contract assets and liabilities.

Leases (Notes)

Leases (Notes)	12 Months Ended
	Dec. 31, 2019
Leases [Abstract]
Leases [Text Block]	LEASES As a lessee, the Corporation has entered into operating leases for the majority of its real estate locations, primarily retail and office space. Total lease expenses were $ 81 million , including $ 64 million of operating lease expense and $ 19 million of variable lease expense, reported net of $2 million in sublease income, for the year ended December 31, 2019 . At December 31, 2019 , the Corporation's Right of Use (ROU) assets and operating lease liabilities were $329 million and $367 million , respectively. The weighted average lease term for the lease liabilities was 9 years, and the weighted average discount rate of remaining payments was 3.78 percent . Lease liabilities from new ROU assets obtained during the year ended December 31, 2019 totaled $49 million . Cash paid on operating lease liabilities was $67 million for the year ended December 31, 2019 . As of December 31, 2019 , the contractual maturities of operating lease liabilities were as follows: (in millions) Years Ending December 31 2020 $ 60 2021 62 2022 53 2023 46 2024 42 Thereafter 175 Total contractual maturities 438 Less imputed interest (71 ) Total operating lease liabilities $ 367 As a lessor, the Corporation leases certain types of manufacturing and warehouse equipment as well as public and private transportation vehicles to its customers. The Corporation recognized lease-related revenue, primarily interest income from sales-type and direct financing leases of $14 million for the year ended December 31, 2019 . At December 31, 2019 , the Corporation's net investment in sales-type and direct financing leases was $369 million . As of December 31, 2019 , the contractual maturities of sales-type and direct financing lease receivables were as follows: (in millions) Years Ending December 31 2020 $ 66 2021 54 2022 90 2023 45 2024 40 Thereafter 31 Total lease payments receivable 326 Unguaranteed residual values 64 Less deferred interest income (21 ) Total lease receivables (a) $ 369 (a) Excludes net investment in leveraged leases of $219 million .

Basis of Presentation and Acc_2

Basis of Presentation and Accounting Policies Basis of Presentation and Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2019
Accounting Policies [Abstract]
Principles of Consolidation	Principles of Consolidation The consolidated financial statements include the accounts of the Corporation and the accounts of those subsidiaries that are majority owned and in which the Corporation has a controlling financial interest. The Corporation consolidates entities not determined to be variable interest entities (VIEs) when it holds a controlling financial interest and uses the cost or equity method when it holds less than a controlling financial interest. In consolidation, all significant intercompany accounts and transactions are eliminated. The results of operations of companies acquired are included from the date of acquisition. The Corporation holds investments in certain legal entities that are considered VIEs. In general, a VIE is an entity that either (1) has an insufficient amount of equity to carry out its principal activities without additional subordinated financial support, (2) has a group of equity owners that are unable to make significant decisions about its activities, or (3) has a group of equity owners that do not have the obligation to absorb losses or the right to receive returns generated by its operations. If any of these characteristics are present, the entity is subject to a variable interests consolidation model, and consolidation is based on variable interests, not on voting interests. Variable interests are defined as contractual ownership or other money interests in an entity that change with fluctuations in the entity’s net asset value. The primary beneficiary is required to consolidate the VIE. The primary beneficiary is defined as the party that has both the power to direct the activities of the VIE that most significantly impact the entity’s economic performance and the obligation to absorb losses or the right to receive benefits that could be significant to the VIE. The maximum potential exposure to losses relative to investments in VIEs is generally limited to the sum of the outstanding book basis and unfunded commitments for future investments. The Corporation evaluates its investments in VIEs, both at inception and when there is a change in circumstances that requires reconsideration, to determine if the Corporation is the primary beneficiary and consolidation is required. The Corporation accounts for unconsolidated VIEs using either the proportional, cost or equity method. These investments comprise investments in community development projects which generate tax credits to their investors and are included in accrued income and other assets on the Consolidated Balance Sheets. The proportional method is used for investments in affordable housing projects that qualify for the low-income housing tax credit (LIHTC). The equity method is used for other investments where the Corporation has the ability to exercise significant influence over the entity’s operation and financial policies. Other unconsolidated equity investments that do not meet the criteria to be accounted for under the equity method are accounted for under the cost method. Amortization and other write-downs of LIHTC investments are presented on a net basis as a component of the provision for income taxes, while income, amortization and write-downs from cost and equity method investments are recorded in other noninterest income on the Consolidated Statements of Income. Assets held in an agency or fiduciary capacity are not assets of the Corporation and are not included in the consolidated financial statements.
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. Fair value is an estimate of the exchange price that would be received to sell an asset or paid to transfer a liability in an orderly transaction (i.e., not a forced transaction, such as a liquidation or distressed sale) between market participants at the measurement date. Fair value is based on the assumptions market participants would use when pricing an asset or liability. 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 impaired loans, 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. Fair value measurements and disclosures guidance establishes a three-level fair value hierarchy based on the markets in which the assets and liabilities are traded and the reliability of the assumptions used to determine fair value. The fair value hierarchy gives the highest priority to quoted prices in active markets and the lowest priority to unobservable data. Fair value measurements are separately disclosed by level within the fair value hierarchy. For assets and liabilities recorded at fair value, it is the Corporation’s policy to maximize the use of observable inputs and minimize the use of unobservable inputs when developing fair value measurements. Level 1 Valuation is based upon quoted prices for identical instruments traded in active markets. Level 2 Valuation is based upon quoted prices for similar instruments in active markets, quoted prices for identical or similar instruments in markets that are less active, and model-based valuation techniques for which all significant assumptions are observable in the market. Level 3 Valuation is generated from model-based techniques that use at least one significant assumption not observable in the market. These unobservable assumptions reflect estimates of assumptions that market participants would use in pricing the asset or liability. Valuation techniques include use of option pricing models, discounted cash flow models and similar techniques. The Corporation generally utilizes third-party pricing services to value Level 1 and Level 2 securities. Management reviews the methodologies and assumptions used by the third-party pricing services and evaluates the values provided, principally by comparison with other available market quotes for similar instruments and/or analysis based on internal models using available third-party market data. The Corporation may occasionally adjust certain values provided by the third-party pricing service when management believes, as the result of its review, that the adjusted price most appropriately reflects the fair value of the particular security. Fair value measurements for assets and liabilities where limited or no observable market data exists are based primarily upon estimates, often calculated based on the economic and competitive environment, the characteristics of the asset or liability and other factors. Therefore, the results cannot be determined with precision and may not be realized in an actual sale or immediate settlement of the asset or liability. Additionally, there may be inherent weaknesses in any calculation technique, and changes in the underlying assumptions used, including discount rates and estimates of future cash flows, could significantly affect the results of current or future values. Following are 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. The descriptions include an indication of the level of the fair value hierarchy in which the assets or liabilities are classified. Transfers of assets or liabilities between levels of the fair value hierarchy are recognized at the beginning of the reporting period, when applicable. Cash and due from banks, federal funds sold and interest-bearing deposits with banks Due to their short-term nature, the carrying amount of these instruments approximates the estimated fair value. As such, the Corporation classifies the estimated fair value of these instruments as Level 1. Deferred compensation plan assets and liabilities as well as equity securities with a readily determinable fair value The Corporation holds a portfolio of securities including equity securities and assets held related to deferred compensation plans. Securities and associated deferred compensation plan liabilities are recorded at fair value on a recurring basis and included in other short-term investments and accrued expenses and other liabilities, respectively, on the Consolidated Balance Sheets. Level 1 securities include assets related to deferred compensation plans, which are invested in mutual funds, U.S. Treasury securities that are traded by dealers or brokers in active over-the-counter markets and other securities traded on an active exchange, such as the New York Stock Exchange. Deferred compensation plan liabilities represent the fair value of the obligation to the employee, which corresponds to the fair value of the invested assets. Level 2 securities include municipal bonds and residential mortgage-backed securities issued by U.S. government-sponsored entities and corporate debt securities. The methods used to value equity securities and deferred compensation plan assets are the same as the methods used to value investment securities, discussed below. Investment securities Investment securities available-for-sale are recorded at fair value on a recurring basis. The Corporation discloses estimated fair values of investment securities held-to-maturity, which is determined in the same manner as investment securities available-for-sale. Level 1 securities include those traded on an active exchange, such as the New York Stock Exchange, U.S. Treasury securities that are traded by dealers or brokers in active over-the-counter markets and money market funds. Level 2 securities include residential mortgage-backed securities issued by U.S. government agencies and U.S. government-sponsored entities and corporate debt securities. The fair value of Level 2 securities is determined using quoted prices of securities with similar characteristics, or pricing models based on observable market data inputs, primarily interest rates, spreads and prepayment information. Securities classified as Level 3 represent securities in less liquid markets requiring significant management assumptions when determining fair value. The Corporate Treasury department, with appropriate oversight and approval provided by senior management, is responsible for the valuation of Level 3 securities. Valuation results, including an analysis of changes to the valuation methodology, are provided to senior management for review on a quarterly basis. Loans held-for-sale Loans held-for-sale, included in other short-term investments on the Consolidated Balance Sheets, are recorded at the lower of cost or fair value. Loans held-for-sale may be carried at fair value on a nonrecurring basis when fair value is less than cost. The fair value is based on what secondary markets are currently offering for portfolios with similar characteristics. As such, the Corporation classifies both loans held-for-sale subjected to nonrecurring fair value adjustments and the estimated fair value of loans held-for sale as Level 2. Loans The Corporation does not record loans at fair value on a recurring basis. However, the Corporation may establish a specific allowance for an impaired loan based on the fair value of the underlying collateral. Such loan values are reported as nonrecurring fair value measurements. Collateral values supporting individually evaluated impaired loans are evaluated quarterly. When management determines that the fair value of the collateral requires additional adjustments, either as a result of non-current appraisal value or when there is no observable market price, the Corporation classifies the impaired loan as Level 3. The Special Assets Group is responsible for performing quarterly credit quality reviews for all impaired loans as part of the quarterly allowance for loan losses process overseen by the Chief Credit Officer, during which valuation adjustments to updated collateral values are determined. The Corporation discloses fair value estimates for loans. The estimated fair value is determined based on characteristics such as loan category, repricing features and remaining maturity, and includes prepayment and credit loss estimates. Fair values are estimated using a discounted cash flow model that employs discount rates that reflects current pricing for loans with similar maturity and risk characteristics, including credit characteristics, and the cost of equity for the portfolio at the balance sheet date. The rates take into account the expected yield curve, as well as an adjustment for prepayment risk, when applicable. The Corporation classifies the estimated fair value of loans held for investment as Level 3. Customers’ liability on acceptances outstanding and acceptances outstanding Customers' liability on acceptances outstanding is included in accrued income and other assets and acceptances outstanding are included in accrued expenses and other liabilities on the Consolidated Balance Sheets. Due to their short-term nature, the carrying amount of these instruments approximates the estimated fair value. As such, the Corporation classifies the estimated fair value of these instruments as Level 1. Derivative assets and derivative liabilities Derivative instruments held or issued for risk management or customer-initiated activities are traded in over-the-counter markets where quoted market prices are not readily available. Fair value for over-the-counter derivative instruments is measured on a recurring basis using internally developed models that use primarily market observable inputs, such as yield curves and option volatilities. The Corporation manages credit risk on its derivative positions based on whether the derivatives are being settled through a clearinghouse or bilaterally with each counterparty. For derivative positions settled on a counterparty-by-counterparty basis, the Corporation calculates credit valuation adjustments, included in the fair value of these instruments, on the basis of its relationships at the counterparty portfolio/master netting agreement level. These credit valuation adjustments are determined by applying a credit spread for the counterparty or the Corporation, as appropriate, to the total expected exposure of the derivative after considering collateral and other master netting arrangements. These adjustments, which are considered Level 3 inputs, are based on estimates of current credit spreads to evaluate the likelihood of default. When credit valuation adjustments are significant to the overall fair value of a derivative, the Corporation classifies the over-the-counter derivative valuation in Level 3 of the fair value hierarchy; otherwise, over-the-counter derivative valuations are classified in Level 2. Nonmarketable equity securities The Corporation has a portfolio of indirect (through funds) private equity and venture capital investments with a carrying value of $5 million and unfunded commitments of less than $1 million , at December 31, 2019 . The investments are accounted for either on the cost or equity method and are individually reviewed for impairment on a quarterly basis by comparing the carrying value to the estimated fair value. These investments may be carried at fair value on a nonrecurring basis when they are deemed to be impaired and written down to fair value. Where there is not a readily determinable fair value, the Corporation estimates fair value for indirect private equity and venture capital investments based on the net asset value, as reported by the fund. The Corporation also holds restricted equity investments, primarily Federal Home Loan Bank (FHLB) and Federal Reserve Bank (FRB) stock. Restricted equity securities are not readily marketable and are recorded at cost (par value) in accrued income and other assets on the Consolidated Balance Sheets and evaluated for impairment based on the ultimate recoverability of the par value. No significant observable market data for these instruments is available. The Corporation considers the profitability and asset quality of the issuer, dividend payment history and recent redemption experience and believes its investments in FHLB and FRB stock are ultimately recoverable at par. Therefore, the carrying amount for these restricted equity investments approximates fair value. The Corporation classifies the estimated fair value of such investments as Level 1. The Corporation’s investment in FHLB stock totaled $163 million at both December 31, 2019 and 2018 , and its investment in FRB stock totaled $85 million at both December 31, 2019 and 2018 . Other real estate Other real estate is included in accrued income and other assets on the Consolidated Balance Sheets and includes primarily foreclosed property. Foreclosed property is initially recorded at fair value, less costs to sell, at the date of legal title transfer to the Corporation, establishing a new cost basis. Subsequently, foreclosed property is carried at the lower of cost or fair value, less costs to sell. Other real estate may be carried at fair value on a nonrecurring basis when fair value is less than cost. Fair value is based upon independent market prices, appraised value or management's estimate of the value of the property. The Special Assets Group obtains updated independent market prices and appraised values, as required by state regulation or deemed necessary based on market conditions, and determines if additional write-downs are necessary. On a quarterly basis, senior management reviews all other real estate and determines whether the carrying values are reasonable, based on the length of time elapsed since receipt of independent market price or appraised value and current market conditions. When management determines that the fair value of other real estate requires additional adjustments, either as a result of a non-current appraisal or when there is no observable market price, the Corporation classifies the other real estate as Level 3. Deposit liabilities The estimated fair value of checking, savings and certain money market deposit accounts is represented by the amounts payable on demand. The estimated fair value of term deposits is calculated by discounting the scheduled cash flows using the period-end rates offered on these instruments. As such, the Corporation classifies the estimated fair value of deposit liabilities as Level 2. Short-term borrowings The carrying amount of federal funds purchased, securities sold under agreements to repurchase and other short-term borrowings approximates the estimated fair value. As such, the Corporation classifies the estimated fair value of short-term borrowings as Level 1. Medium- and long-term debt The estimated fair value of the Corporation's medium- and long-term debt is based on quoted market values when available. If quoted market values are not available, the estimated fair value is based on the market values of debt with similar characteristics. The Corporation classifies the estimated fair value of medium- and long-term debt as Level 2. Credit-related financial instruments Credit-related financial instruments include unused commitments to extend credit and letters of credit. These instruments generate ongoing fees which are recognized over the term of the commitment. In situations where credit losses are probable, the Corporation records an allowance. The carrying value of these instruments included in accrued expenses and other liabilities on the Consolidated Balance Sheets, which includes the carrying value of the deferred fees plus the related allowance, approximates the estimated fair value. The Corporation classifies the estimated fair value of credit-related financial instruments as Level 3.
Other Short-Term Investments	Other Short-Term Investments Other short-term investments include deferred compensation plan assets, equity securities with a readily determinable fair value and loans held-for-sale. Deferred compensation plan assets and equity securities are carried at fair value. Realized and unrealized gains or losses are included in other noninterest income on the Consolidated Statements of Income. Loans held-for-sale, typically residential mortgages originated with the intent to sell and occasionally including other loans transferred to held-for-sale, are carried at the lower of cost or fair value. Fair value is determined in the aggregate for each portfolio. Changes in fair value and gains or losses upon sale are included in other noninterest income on the Consolidated Statements of Income.
Investment Securities	Investment Securities Debt securities are classified as trading, available-for-sale or held-to-maturity. Trading securities are recorded at fair value, with unrealized gains and losses included in noninterest income on the Consolidated Statements of Income. Securities available-for-sale are recorded at fair value, with unrealized gains and losses, net of income taxes, reported as a separate component of other comprehensive income (OCI). Securities for which management has the intent and ability to hold to maturity are classified as held-to-maturity and recorded at amortized cost. Interest income is recognized using the interest method. Securities transferred from available-for-sale to held-to-maturity are reclassified at fair value on the date of transfer. The net unrealized gain (loss) at the date of transfer is included in historical cost and amortized over the remaining life of the related securities as a yield adjustment consistent with the amortization of the net unrealized gain (loss) included in accumulated other comprehensive loss on the same securities, resulting in no impact to net income. Debt securities are reviewed quarterly for possible other-than-temporary impairment (OTTI). In determining whether OTTI exists for debt securities in an unrealized loss position, the Corporation assesses the likelihood of selling the security prior to the recovery of its amortized cost basis. If the Corporation intends to sell the debt security or it is more likely than not that the Corporation will be required to sell the debt security prior to the recovery of its amortized cost basis, the debt security is written down to fair value, and the full amount of any impairment charge is recorded as a loss in net securities losses on the Consolidated Statements of Income. If the Corporation does not intend to sell the debt security and it is more likely than not that the Corporation will not be required to sell the debt security prior to recovery of its amortized cost basis, only the credit component of any impairment of a debt security is recognized as a loss in net securities losses on the Consolidated Statements of Income, with the remaining impairment recorded in OCI. Gains or losses on the sale of securities are computed based on the adjusted cost of the specific security sold. For further information on investment securities, refer to Note 3 .
Loans	Loans Loans and leases originated and held for investment are recorded at the principal balance outstanding, net of unearned income, charge-offs and unamortized deferred fees and costs. Interest income is recognized on loans and leases using the interest method. The Corporation assesses all loan modifications to determine whether a restructuring constitutes a TDR. A restructuring is considered a TDR when a borrower is experiencing financial difficulty and the Corporation grants a concession to the borrower. TDRs on accrual status at the original contractual rate of interest are considered performing. Nonperforming TDRs include TDRs on nonaccrual status and loans which have been renegotiated to less than the original contractual rates (reduced-rate loans). All TDRs are considered impaired loans.
Loan Origination Fees and Costs	Loan Origination Fees and Costs Substantially all loan origination fees and costs are deferred and amortized to net interest income over the life of the related loan or over the commitment period as a yield adjustment. Net deferred income on originated loans, including unearned income and unamortized costs, fees, premiums and discounts, totaled $103 million and $115 million at December 31, 2019 and 2018 , respectively. Loan fees on unused commitments and net origination fees related to loans sold are recognized in noninterest income.
Allowance for Credit Losses	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 traditional residential mortgage, home equity and other consumer loans. For further information on the Allowance for Credit Losses, refer to Note 4 . Allowance for Loan Losses The allowance for loan losses represents management’s assessment of probable, estimable losses inherent in the Corporation’s loan portfolio. The allowance for loan losses includes specific allowances, based on individual evaluations of certain loans, and allowances for homogeneous pools of loans with similar risk characteristics. The Corporation individually evaluates certain impaired loans on a quarterly basis and establishes specific allowances for such loans, if required. A loan is considered impaired when it is probable that interest or principal payments will not be made in accordance with the contractual terms of the loan agreement. Consistent with this definition, all loans for which the accrual of interest has been discontinued (nonaccrual loans) are considered impaired. The Corporation individually evaluates nonaccrual loans with book balances of $2 million or more and loans whose terms have been modified in a TDR with book balances of $1 million or more. The threshold for individual evaluation is revised on an infrequent basis, generally when economic circumstances change significantly. Specific allowances for impaired loans are estimated using one of several methods, including the estimated fair value of underlying collateral, observable market value of similar debt or discounted expected future cash flows. Collateral values supporting individually evaluated impaired loans are evaluated quarterly. Generally, appraisals are obtained or appraisal assumptions are updated annually, unless conditions dictate increased frequency. The Corporation may reduce the collateral value based upon the age of the appraisal and adverse developments in market conditions. Loans which do not meet the criteria to be evaluated individually are evaluated in homogeneous pools of loans with similar risk characteristics. Business loans are assigned to pools based on the Corporation's internal risk rating system. Internal risk ratings are assigned to each business loan at the time of approval and are subjected to subsequent periodic reviews by the Corporation’s senior management, generally at least annually or more frequently upon the occurrence of a circumstance that affects the credit risk of the loan. For business loans not individually evaluated, losses inherent to the pool are estimated by applying standard reserve factors to outstanding principal balances. Standard reserve factors are based on estimated probabilities of default for each internal risk rating, set to a default horizon based on an estimated loss emergence period, and loss given default. These factors are evaluated quarterly and updated annually, unless economic conditions necessitate a change, giving consideration to count-based borrower risk rating migration experience and trends, recent charge-off experience, current economic conditions and trends, changes in collateral values of properties securing loans, and trends with respect to past due and nonaccrual amounts. The allowance for business loans not individually evaluated 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 (i) risk factors that have not been fully addressed in internal risk ratings, (ii) imprecision in the risk rating system resulting from inaccuracy in assigning and/or entering risk ratings in the loan accounting system, (iii) market conditions and (iv) model imprecision. Risk factors that have not been fully addressed in internal risk ratings may include portfolios where recent historical losses exceed expected losses or known recent events are expected to alter risk ratings once evidence is acquired, portfolios where a certain level of concentration introduces added risk, or changes in the level and quality of experience held by lending management. An additional allowance for risk rating errors is calculated based on the results of risk rating accuracy assessments performed on samples of business loans conducted by the Corporation's asset quality review function, a function independent of the lending and credit groups responsible for assigning the initial internal risk rating at the time of approval. Qualitative adjustments for market conditions are determined based on an established framework. The determination of the appropriate adjustment is based on management's analysis of observable macroeconomic metrics, including consideration of regional metrics within the Corporation's footprint, internal credit risk movement and a qualitative assessment of the lending environment, including underwriting standards, current economic and political conditions, and other factors affecting credit quality. 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 assumption. The allowance for retail loans not individually evaluated is determined by applying estimated loss rates to various pools of loans within the portfolios with similar risk characteristics. Estimated loss rates for all pools are updated quarterly, incorporating quantitative and qualitative factors such as recent charge-off experience, current economic conditions and trends, changes in collateral values of properties securing loans (using index-based estimates), and trends with respect to past due and nonaccrual amounts. The total allowance for loan losses is sufficient to absorb incurred losses inherent in the total portfolio. Unanticipated economic events, including political, economic and regulatory instability in countries where the Corporation has loans, could cause changes in the credit characteristics of the portfolio and result in an unanticipated increase in the allowance. Significant increases in current portfolio exposures, as well as the inclusion of additional industry-specific portfolio exposures in the allowance, could also increase the amount of the allowance. Any of these events, or some combination thereof, 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. Allowance for Credit Losses on Lending-Related Commitments The allowance for credit losses on lending-related commitments provides for probable losses inherent in lending-related commitments, including unused commitments to extend credit and letters of credit. The allowance for credit losses on lending-related commitments includes allowances based on homogeneous pools of letters of credit and unused commitments to extend credit within each internal risk rating. A probability of draw estimate is applied to the commitment amount, and the result is multiplied by standard reserve factors consistent with business loans. In general, the probability of draw for letters of credit is considered certain for all letters of credit supporting loans and for letters of credit assigned an internal risk rating generally consistent with regulatory defined substandard or doubtful. Other letters of credit and all unfunded commitments have a lower probability of draw. 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 reflected in the provision for credit losses on the Consolidated Statements of Income.
Nonperforming Assets	Nonperforming Assets Nonperforming assets consist of nonaccrual loans, reduced-rate loans and foreclosed property. A loan is considered past due when the contractually required principal or interest payment is not received by the specified due date or, for certain loans, when a scheduled monthly payment is past due and unpaid for 30 days or more. Business loans are generally placed on nonaccrual status when management determines full collection of principal or interest is unlikely or when principal or interest payments are 90 days past due, unless the loan is fully collateralized and in the process of collection. The past-due status of a business loan is one of many indicative factors considered in determining the collectibility of the credit. The primary driver of when the principal amount of a business loan should be fully or partially charged-off is based on a qualitative assessment of the recoverability of the principal amount from collateral and other cash flow sources. Residential mortgage and home equity loans are generally placed on nonaccrual status once they become 90 days past due and are charged off to current appraised values less costs to sell no later than 180 days past due. In addition, junior lien home equity loans less than 90 days past due are placed on nonaccrual status if they have underlying risk characteristics that place full collection of the loan in doubt, such as when the related senior lien position is identified as seriously delinquent. Residential mortgage and consumer loans in bankruptcy for which the court has discharged the borrower's obligation and the borrower has not reaffirmed the debt are placed on nonaccrual status and written down to estimated collateral value, without regard to the actual payment status of the loan, and are classified as TDRs. All other consumer loans are generally placed on nonaccrual status at 90 days past due and are charged off at no later than 120 days past due, or earlier if deemed uncollectible. At the time a loan is placed on nonaccrual status, interest previously accrued but not collected is charged against current income. Principal and interest payments received on such loans are generally first applied as a reduction of principal. Income on nonaccrual loans is then recognized only to the extent that cash is received after principal has been fully repaid or future collection of principal is probable. Generally, a loan may be returned to accrual status when all delinquent principal and interest have been received and the Corporation expects repayment of the remaining contractual principal and interest, or when the loan or debt security is both well secured and in the process of collection. Foreclosed property (primarily real estate) is initially recorded at fair value, less costs to sell, at the date of legal title transfer to the Corporation and subsequently carried at the lower of cost or fair value, less estimated costs to sell. Loans are reclassified to foreclosed property upon obtaining legal title to the collateral. Independent appraisals are obtained to substantiate the fair value of foreclosed property at the time of foreclosure and updated at least annually or upon evidence of deterioration in the property’s value. At the time of foreclosure, the adjustment for the difference between the related loan balance and fair value (less estimated costs to sell) of the property acquired is charged or credited to the allowance for loan losses. Subsequent write-downs, operating expenses and losses upon sale, if any, are charged to noninterest expenses. Foreclosed property is included in accrued income and other assets on the Consolidated Balance Sheets.
Premises and Equipment	Premises and Equipment Premises and equipment are stated at cost, less accumulated depreciation and amortization. Depreciation, computed using the straight-line method, is charged to operations over the estimated useful lives of the assets. Estimated useful lives are generally 3 years to 33 years for premises that the Corporation owns and 3 years to 8 years for furniture and equipment. Leasehold improvements are generally amortized over the terms of their respective leases or 10 years, whichever is shorter.
Operating Leases	Operating Leases Effective January 1, 2019, the Corporation adopted the provisions of Accounting Standards Update (ASU) No. 2016-02, “Leases (Topic 842),” (ASU 2016-02), for all open leases with a term greater than one year as of the adoption date, using the modified retrospective approach. Prior comparable periods are presented in accordance with previous guidance under Accounting Standards Codification (ASC) 840, “Leases.” Topic 842 requires the recognition of a lease liability, measured as the present value of unpaid lease payments for operating leases where the Corporation is the lessee, and a corresponding right-of-use (ROU) asset for the right to use the leased properties. The Corporation elected not to reassess whether contracts are or contain leases, lease classification or initial direct costs for existing leases, a set of practical expedients for transition provided by ASU 2016-12. Further, the Corporation elected the practical expedient to use hindsight in determining the lease term and assessing impairment. The election of the hindsight practical expedient resulted in longer lease terms for a limited number of strategic locations based on relevant factors as of the adoption date. The impact at adoption was increases of $329 million and $343 million to total assets and liabilities, respectively, and a $14 million reduction to retained earnings. The increase in total assets was due to the recognition of ROU assets recorded in accrued income and other assets, and the increase in total liabilities was due to corresponding recognition of lease payment liabilities recorded in accrued expenses and other liabilities. Operating lease liabilities reflect the Corporation’s obligation to make future lease payments, primarily for real estate locations. Lease terms typically comprise contractual terms but may include extension options reasonably certain of being exercised at lease inception for certain strategic locations such as regional headquarters. Payments are discounted using the rate the Corporation would pay to borrow amounts equal to the lease payments over the lease term (the Corporation’s incremental borrowing rate). The Corporation does not separate lease and non-lease components for contracts in which it is the lessee. ROU assets are measured based on lease liabilities adjusted for incentives as well as accrued and prepaid rent. Operating lease expense is recognized on a straight-line basis over the lease term, while variable lease payments are recognized as incurred. Common area maintenance and other executory costs are the main components of variable lease payments. Operating and variable lease expenses are recorded in net occupancy expense on the Consolidated Statements of Income.
Software	Software Capitalized software is stated at cost, less accumulated amortization. Capitalized software includes purchased software, capitalizable application development costs associated with internally-developed software and cloud computing arrangements, including an in-substance software license. Amortization, computed on the straight-line method, is charged to operations over the estimated useful life of the software, generally 5 years. Capitalized software is included in accrued income and other assets on the Consolidated Balance Sheets.
Goodwill	Goodwill and Core Deposit Intangibles 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 Business Bank, the Retail Bank and Wealth Management. The Corporation performs its annual evaluation of goodwill impairment in the third quarter of each year and on an interim basis if events or changes in circumstances between annual tests suggest additional testing may be warranted to determine if goodwill might be impaired. The goodwill impairment test is a two-step test. The first step of the goodwill impairment 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, the second step must be performed to determine the implied fair value of the reporting unit's goodwill and the amount of goodwill impairment, if any. The implied fair value of goodwill is determined as if the reporting unit were being acquired in a business combination. If the implied fair value of goodwill exceeds the goodwill assigned to the reporting unit, there is no impairment. If the goodwill assigned to a reporting unit exceeds the implied fair value of goodwill, an impairment charge would be recorded for the excess. The Corporation may choose to perform a qualitative assessment to determine whether it is more likely than not that the fair value of any reporting unit is less than its carrying amount, including goodwill. 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, events affecting the Corporation as a whole or its reporting units individually and previous results of goodwill impairment tests. Based on the results of the qualitative analysis, the Corporation determines whether a two-step quantitative test is deemed necessary. Core deposit intangibles are amortized on an accelerated basis, based on the estimated period the economic benefits are expected to be received. Core deposit intangibles are reviewed for impairment when events or changes in circumstances indicate that their carrying amounts may not be recoverable. Impairment for a finite-lived intangible asset exists if the sum of the undiscounted cash flows expected to result from the use of the asset exceeds its carrying value. Additional information regarding goodwill and core deposit intangibles can be found in Note 7 .
Nonmarketable Equity Securities	Nonmarketable Equity Securities The Corporation has certain investments that are not readily marketable. These investments include a portfolio of investments in indirect private equity and venture capital funds and restricted equity investments, which are securities the Corporation is required to hold for various reasons, primarily Federal Home Loan Bank of Dallas (FHLB) and Federal Reserve Bank (FRB) stock. These investments are accounted for on the cost or equity method and are included in accrued income and other assets on the Consolidated Balance Sheets. The investments are individually reviewed for impairment on a quarterly basis. Indirect private equity and venture capital funds are evaluated by comparing the carrying value to the estimated fair value. The amount by which the carrying value exceeds the fair value that is determined to be other-than-temporary impairment is charged to current earnings and the carrying value of the investment is written down accordingly. FHLB and FRB stock are recorded at cost (par value) and evaluated for impairment based on the ultimate recoverability of the par value. If the Corporation does not expect to recover the full par value, the amount by which the par value exceeds the ultimately recoverable value would be charged to current earnings and the carrying value of the investment would be written down accordingly.
Derivative Instruments and Hedging Activities	Derivative Instruments and Hedging Activities Derivative instruments are carried at fair value in either accrued income and other assets or accrued expenses and other liabilities on the Consolidated Balance Sheets. The accounting for changes in the fair value (i.e., gains or losses) of a derivative instrument is determined by whether it has been designated and qualifies as part of a hedging relationship and, further, by the type of hedging relationship. The Corporation presents derivative instruments at fair value on the Consolidated Balance Sheets on a net basis when a right of offset exists, based on transactions with a single counterparty and any cash collateral paid to and/or received from that counterparty for derivative contracts that are subject to legally enforceable master netting arrangements. For derivative instruments designated and qualifying as fair value hedges (e.g., hedging the exposure to changes in the fair value of an asset or a liability or an identified portion thereof that is attributable to a particular risk), the gain or loss on the derivative instrument, as well as the offsetting loss or gain on the hedged item attributable to the hedged risk, are recognized in the same consolidated statement of income line that is used to present the earnings effect of the hedged item during the period of the change in fair values. For derivative instruments that are designated and qualify as cash flow hedges (e.g., hedging the exposure to variability in expected future cash flows that is attributable to a particular risk), the gain or loss on the derivative instrument is reported as a component of other comprehensive income and reclassified into earnings in the same consolidated statement of income line item as the earnings effect of the hedged item in the same period or periods during which the hedged transaction affects earnings. For derivative instruments not designated as hedging instruments, the gain or loss is recognized in current earnings during the period of change. To qualify for the use of hedge accounting, a derivative must be effective at inception and expected to be continuously effective in offsetting the risk being hedged. For derivatives designated as hedging instruments at inception, the Corporation uses either the short-cut method or applies statistical regression analysis to assess effectiveness. The short-cut method is used for $2.1 billion notional of fair value hedges of medium- and long-term debt. This method allows for the assumption of perfect effectiveness and eliminates the requirement to further assess hedge effectiveness on these transactions. For hedge relationships to which the Corporation does not apply the short-cut method, statistical regression analysis is used at inception to assess whether the derivative used is expected to be highly effective in offsetting changes in the fair value or cash flows of the hedged item. A statistical regression or qualitative analysis is performed at each reporting period thereafter to evaluate hedge effectiveness. Further information on the Corporation’s derivative instruments and hedging activities is included in Note 8 .
Short-Term Borrowings	Short-Term Borrowings Securities sold under agreements to repurchase are treated as collateralized borrowings and are recorded at amounts equal to the cash received. The contractual terms of the agreements to repurchase may require the Corporation to provide additional collateral if the fair value of the securities underlying the borrowings declines during the term of the agreement.
Financial Guarantees	Financial Guarantees Certain guarantee contracts or indemnification agreements that contingently require the Corporation, as guarantor, to make payments to the guaranteed party are initially measured at fair value and included in accrued expenses and other liabilities on the Consolidated Balance Sheets. The subsequent accounting for the liability depends on the nature of the underlying guarantee. The release from risk is accounted for under a particular guarantee when the guarantee expires or is settled, or by a systematic and rational amortization method. Further information on the Corporation’s obligations under guarantees is included in Note 8 .
Share-Based Compensation	Share-Based Compensation The Corporation recognizes share-based compensation expense using the straight-line method over the requisite service period for all stock awards, including those with graded vesting. The requisite service period is the period an employee is required to provide service in order to vest in the award, which cannot extend beyond the date at which the employee is no longer required to perform any service to receive the share-based compensation (i.e. the retirement-eligible date). Forfeiture of stock awards and dividend equivalents are accounted for as they occur. Certain awards are contingent upon performance and/or market conditions, which affect the number of shares ultimately issued. The Corporation periodically evaluates the probable outcome of the performance conditions and makes cumulative adjustments to compensation expense as appropriate. Market conditions are included in the determination of the fair value of the award on the date of grant. Subsequent to the grant date, market conditions have no impact on the amount of compensation expense the Corporation will recognize over the life of the award. Further information on the Corporation’s share-based compensation plans is included in Note 16 .
Revenue Recognition	Revenue Recognition Revenue from contracts with customers comprises the noninterest income earned by the Corporation in exchange for services provided to customers and is recognized when services are completed or as they are rendered, although contracts are generally short-term by nature. Services provided over a period of time are typically transferred to customers evenly over the term of the contracts and revenue is recognized accordingly over the period services are provided. Contract receivables are included in accrued income and other assets on the Consolidated Balance Sheets. Payment terms vary by services offered, and the time between completion of performance obligations and payment is typically not significant. Card Fees Card fees comprise interchange and other fee income earned on government card, commercial card, debit/automated teller machine card and merchant payment processing programs. Card fees are presented net of network costs, as performance obligations for card services are limited to transaction processing and settlement with the card network on behalf of the customers. Fees for these services are primarily based on interchange rates set by the network and transaction volume. The Corporation also provides ongoing card program support services, for which fees are based on contractually agreed-upon prices and customer demand for services. Service Charges on Deposit Accounts Service charges on deposit accounts comprise charges on retail and business accounts, including fees for treasury management services. Treasury management services include transaction-based services related to payment processing, overdrafts, non-sufficient funds and other deposit account activity, as well as account management services that are provided over time. Business customers can earn credits depending on deposit balances maintained with the Corporation, which may be used to offset fees. Fees and credits are based on predetermined, agreed-upon rates. Fiduciary Income Fiduciary income includes fees and commissions from asset management, custody, recordkeeping, investment advisory and other services provided primarily to personal and institutional trust customers. Revenue is recognized as the services are performed and is based either on the market value of the assets managed or the services provided, as well as agreed-upon rates. Commercial Lending Fees Commercial lending fees include both revenue from contracts with customers (primarily loan servicing fees) and other sources of revenue. Commercial loan servicing fees are based on contractually agreed-upon prices and when the services are provided. Other sources of revenue in commercial lending fees primarily include fees assessed on the unused portion of commercial lines of credit (unused commitment fees) and syndication arrangements. Brokerage Fees Brokerage fees are commissions earned for facilitating securities transactions for customers, as well as other brokerage services provided. Revenue is recognized when services are completed and is based on the type of services provided and agreed-upon rates. The Corporation pays commissions based on brokerage fee revenue. These are typically recognized when incurred because the amortization period is one year or less and are included in salaries and benefits expense on the Consolidated Statements of Income. Other Revenues Other revenues, consisting primarily of other retail fees, investment banking fees and insurance commissions, are typically recognized when services or transactions are completed and are based on the type of services provided and agreed-upon rates. Except as discussed above, commissions and other incentives paid to employees are generally based on several internal and external metrics and, as a result, are not solely dependent on revenue generating activities.
Defined Benefit Pension and Other Postretirement Costs	Defined Benefit Pension and Other Postretirement Costs Defined benefit pension costs are funded consistent with the requirements of federal laws and regulations. Inherent in the determination of defined benefit pension costs are assumptions concerning future events that will affect the amount and timing of required benefit payments under the plans. These assumptions include demographic assumptions such as retirement age and mortality, a compensation rate increase, a discount rate used to determine the current benefit obligation, form of payment election and a long-term expected rate of return on plan assets. Net periodic defined benefit pension expense includes service cost, interest cost based on the assumed discount rate, an expected return on plan assets based on an actuarially derived market-related value of assets, amortization of prior service cost or credit and amortization of net actuarial gains or losses. The market-related value of plan assets is determined by amortizing the current year’s investment gains and losses (the actual investment return net of the expected investment return) over 5 years. The amortization adjustment cannot exceed 10 percent of the fair value of assets. Prior service costs or credits include the impact of plan amendments on the liabilities and are amortized over the future service periods of active employees expected to receive benefits under the plan. Actuarial gains and losses result from experience different from that assumed and from changes in assumptions (excluding asset gains and losses not yet reflected in market-related value). Amortization of actuarial gains and losses is included as a component of net periodic defined benefit pension cost for a year if the actuarial net gain or loss exceeds 10 percent of the greater of the projected benefit obligation or the market-related value of plan assets.If amortization is required, the excess is amortized over the average remaining service period of participating employees expected to receive benefits under the plan. Service costs are included in salaries and benefits expense, while the other components of net periodic defined benefit pension expense are included in other noninterest expenses on the Consolidated Statements of Income. Postretirement benefits are recognized in other noninterest expenses on the Consolidated Statements of Income during the average remaining service period of participating employees expected to receive benefits under the plan or the average remaining future lifetime of retired participants currently receiving benefits under the plan. See Note 17 for further information regarding the Corporation’s defined benefit pension and other postretirement plans.
Income Taxes	Income Taxes The provision for income taxes is the sum of income taxes due for the current year and deferred taxes. The Corporation classifies interest and penalties on income tax liabilities and, beginning January 1, 2017, excess tax benefits and deficiencies resulting from employee stock awards in the provision for income taxes on the Consolidated Statements of Income. Deferred taxes arise from temporary differences between the income tax basis and financial accounting basis of assets and liabilities. Deferred tax assets are evaluated for realization based on available evidence of projected future reversals of existing taxable temporary differences, assumptions made regarding future events and, when applicable, state loss carryback capacity. A valuation allowance is provided when it is more likely than not that some portion of the deferred tax asset will not be realized.
Earnings Per Share	Earnings Per Share Basic net income per common share is calculated using the two-class method. The two-class method is an earnings allocation formula that determines earnings per share for each share of common stock and participating securities according to dividends declared (distributed earnings) and participation rights in undistributed earnings. Distributed and undistributed earnings are allocated between common and participating security shareholders based on their respective rights to receive dividends. Nonvested share-based payment awards that contain nonforfeitable rights to dividends or dividend equivalents are considered participating securities (e.g., nonvested restricted stock and certain service-based restricted stock units). Undistributed net losses are not allocated to nonvested restricted shareholders, as these shareholders do not have a contractual obligation to fund the losses incurred by the Corporation. Net income attributable to common shares is then divided by the weighted-average number of common shares outstanding during the period. Diluted net income per common share is calculated using the more dilutive of either the treasury method or the two-class method. The dilutive calculation considers common stock issuable under the assumed exercise of stock options and warrants, as well as service- and performance-based restricted stock units granted under the Corporation’s stock plans using the treasury stock method, if dilutive. Net income attributable to common shares is then divided by the total of weighted-average number of common shares and common stock equivalents outstanding during the period.
Statements Of Cash Flows	Statements of Cash Flows Cash and cash equivalents are defined as those amounts included in cash and due from banks and interest-bearing deposits with banks on the Consolidated Balance Sheets.
Comprehensive Income (Loss)	Comprehensive Income (Loss) The Corporation presents on an annual basis the components of net income and other comprehensive income in two separate, but consecutive statements and presents on an interim basis the components of net income and a total for comprehensive income in one continuous consolidated statement of comprehensive income.
Pending Accounting Pronouncements	Pending Accounting Pronouncements Current Expected Credit Losses In June 2016, the FASB issued ASU No. 2016-13, "Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments," which addresses concerns regarding the perceived delay in recognition of credit losses under the existing incurred loss model. The amendment introduces a new, single model for recognizing credit losses on all financial instruments presented on a cost basis. Under the new model, entities must estimate current expected credit losses by considering all available relevant information, including historical and current conditions, as well as reasonable and supportable forecasts of future events. Topic 326 also requires additional qualitative and quantitative disclosure to allow users to better understand the credit risk within the portfolio and the methodologies for determining the allowance for credit losses. The Corporation adopted Topic 326 effective January 1, 2020 using the modified retrospective approach. Estimation Methodology The Corporation expects to determine an allowance for the majority of its loan portfolio by applying reserve factors designed to estimate current expected credit losses to amortized cost balances over the remaining contractual life of the portfolio. Loans with similar risk characteristics are aggregated in homogeneous pools. Business loans are assigned to pools based on risk factors including the borrower’s industry; loan type and structure; collateral type; as well as the Corporation’s historical loss patterns and 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 Corporation 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. 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 are selecting the economic forecasts used to calibrate the reserve factors, determining the reasonable and supportable forecast period and choosing the methodology for reverting to appropriate historical credit losses. • 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. The Corporation generally uses a consensus forecast, which may be adjusted after different economic forecasts ranging from more benign to more severe are evaluated, to forecast losses over the contractual life of the loan portfolio. • Forecast Period: Management believes it can reasonably forecast credit losses over a two-year horizon. The two-year forecast period, which is shorter than the loss emergence period used under the incurred methodology, encompasses most of the remaining contractual life of the portfolio of business loans. Management may adjust the forecast period in response to changes in the economic environment. • Reversion Methodology: For contractual periods which extend beyond the two-year forecast horizon, management elected an immediate reversion to an average historical loss experience that generally incorporates a full economic cycle. Credit losses for loans that no longer share similar risk characteristics are estimated on an individual basis. Individual evaluations are typically performed for nonaccrual loans and modified loans classified as troubled debt restructurings. Specific allowances are estimated 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 estimation methodology for credit losses on lending-related commitments is similar to the process for estimating credit losses for loans, with the addition of a probability of draw estimate that is applied to each commitment amount. Topic 326 also requires expected credit losses on available-for-sale (AFS) debt securities 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 Corporation believes the zero-loss expectation currently applies to all its AFS debt securities. Impact of Adoption The Corporation’s estimate of current expected credit losses in accordance with Topic 326 assumes continued moderate economic growth of the U.S. economy and is expected to result 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. Accordingly, the Corporation expects a corresponding increase of $13 million 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 capital (CET1) ratio. Business loans, comprising approximately 91 percent of the Corporation’s total loan portfolio, consist of loans and lending arrangements with generally short contractual maturities, which resulted in an expected reduction of $42 million in the allowance for credit losses. The allowance for credit losses is expected to increase $25 million for retail loans, given their longer contractual maturities. Cloud Computing Arrangements In August 2018, the FASB issued 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," (ASU 2018-15), to align the requirements for capitalizing implementation costs in a hosting arrangement that is a service contract with the requirements for capitalizing implementation costs relating to internal-use software. The update requires entities in a hosting arrangement that is a service contract to follow the guidance in Subtopic 350-40 to determine which implementation costs to capitalize as an asset and which costs to expense. ASU 2018-15 also requires the amortization of capitalized implementation costs over the term of the associated hosting arrangement to be presented in the same line of the Consolidated Statement of Income as the associated hosting arrangement fees. The Corporation adopted ASU 2018-15 prospectively on January 1, 2020. The impact of adoption will depend on the magnitude and timing of upcoming software and hosting arrangement projects as well as the nature of the implementation costs. Additionally, upon adoption, certain fees that were previously classified as outside processing fee expense will be reported in software expense on the Consolidated Statements of Income.

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2019
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 December 31, 2019 and 2018 . (in millions) Total Level 1 Level 2 Level 3 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. (in millions) Total Level 1 Level 2 Level 3 December 31, 2018 Deferred compensation plan assets $ 88 $ 88 $ — $ — Equity securities 43 43 — — Investment securities available-for-sale: U.S. Treasury and other U.S. government agency securities 2,727 2,727 — — Residential mortgage-backed securities (a) 9,318 — 9,318 — Total investment securities available-for-sale 12,045 2,727 9,318 — Derivative assets: Interest rate contracts 67 — 58 9 Energy derivative contracts 189 — 189 — Foreign exchange contracts 19 — 19 — Total derivative assets 275 — 266 9 Total assets at fair value $ 12,451 $ 2,858 $ 9,584 $ 9 Derivative liabilities: Interest rate contracts $ 70 $ — $ 70 $ — Energy derivative contracts 186 — 186 — Foreign exchange contracts 13 — 13 — Total derivative liabilities 269 — 269 — Deferred compensation plan liabilities 88 88 — — Total liabilities at fair value $ 357 $ 88 $ 269 $ — (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 measured at fair value on a recurring basis for the years ended December 31, 2019 and 2018 . Net Realized/Unrealized Gains (Losses) (Pretax) Recorded in Earnings (b) Balance at Beginning of Period Change in Classification (a) Sales and Redemptions Balance at End of Period (in millions) Realized Unrealized Year Ended December 31, 2019 Derivative assets: Interest rate contracts $ 9 $ — $ 1 $ 13 $ (1 ) $ 22 Year Ended December 31, 2018 Equity securities $ — $ 44 $ — $ — $ (44 ) $ — Investment securities available-for-sale: State and municipal securities (c) 5 — — — (5 ) — Equity and other non-debt securities (c) 44 (44 ) — — — — Total investment securities 49 (44 ) — — (5 ) — Derivative assets: Interest rate contracts 14 — — (5 ) — 9 (a) Reflects the reclassification of equity securities resulting from the adoption of ASU 2016-01. (b) Realized and unrealized gains and losses due to changes in fair value recorded in other noninterest income on the Consolidated Statements of Income. (c) Auction-rate securities.
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 December 31, 2019 and 2018 . No liabilities were recorded at fair value on a nonrecurring basis at December 31, 2019 and 2018 . (in millions) Level 3 December 31, 2019 Loans: Commercial $ 70 Total assets at fair value $ 70 December 31, 2018 Business loans: Commercial $ 96 Commercial mortgage 4 Total business loans 100 Retail loans: Residential mortgage 8 Total assets at fair value $ 108
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 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 — Customer 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 ) December 31, 2018 Assets Cash and due from banks $ 1,390 $ 1,390 $ 1,390 $ — $ — Interest-bearing deposits with banks 3,171 3,171 3,171 — — Loans held-for-sale 3 3 — 3 — Total loans, net of allowance for loan losses (a) 49,492 48,889 — — 48,889 Customers’ liability on acceptances outstanding 4 4 4 — — Restricted equity investments 248 248 248 — — Nonmarketable equity securities (b) 6 11 Liabilities Demand deposits (noninterest-bearing) 28,690 28,690 — 28,690 — Interest-bearing deposits 24,740 24,740 — 24,740 — Customer certificates of deposit 2,131 2,100 — 2,100 — Total deposits 55,561 55,530 — 55,530 — Short-term borrowings 44 44 44 — — Acceptances outstanding 4 4 4 — — Medium- and long-term debt 6,463 6,436 — 6,436 — Credit-related financial instruments (57 ) (57 ) — — (57 ) (a) Included $70 million and $108 million of impaired loans recorded at fair value on a nonrecurring basis at December 31, 2019 and 2018 , 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.

Investment Securities (Tables)

Investment Securities (Tables)	12 Months Ended
	Dec. 31, 2019
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 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 December 31, 2018 Investment securities available-for-sale: U.S. Treasury and other U.S. government agency securities $ 2,732 $ 14 $ 19 $ 2,727 Residential mortgage-backed securities (a) 9,493 22 197 9,318 Total investment securities available-for-sale $ 12,225 $ 36 $ 216 $ 12,045 (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 December 31, 2019 and 2018 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 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 December 31, 2018 U.S. Treasury and other U.S. government agency securities $ — $ — $ 1,457 $ 19 $ 1,457 $ 19 Residential mortgage-backed securities (a) 1,008 9 6,412 188 7,420 197 Total temporarily impaired securities $ 1,008 $ 9 $ 7,869 $ 207 $ 8,877 $ 216 (a) Issued and/or guaranteed by U.S. government agencies or U.S. government-sponsored enterprises.
Summary of Net Securities Gains (Losses)	Sales, primarily from repositioning $1.0 billion and $1.3 billion of lower-yielding treasury securities in the years ended December 31, 2019 and 2018 , respectively, of investment securities available-for-sale resulted in the following gains and losses recorded in net securities losses on the Consolidated Statements of Income, computed based on the adjusted cost of the specific security. There were no securities gains or losses for the year ended December 31, 2017 . (in millions) Year Ended December 31 2019 2018 Securities gains $ 1 $ 2 Securities losses (8 ) (21 ) Net securities losses $ (7 ) $ (19 )
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) December 31, 2019 Amortized Cost Fair Value Contractual maturity Within one year $ 30 $ 30 After one year through five years 2,842 2,894 After five years through ten years 1,006 1,013 After ten years 8,435 8,461 Total investment securities $ 12,313 $ 12,398

Credit Quality And Allowance _2

Credit Quality And Allowance For Credit Losses (Tables)	12 Months Ended
	Dec. 31, 2019
Credit Quality And Allowance For Credit Losses [Abstract]
Aging Analysis Of Loans	The following table presents an aging analysis of the recorded balance 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 Total Loans December 31, 2019 Business loans: Commercial $ 27 $ 7 $ 17 $ 51 $ 148 $ 31,274 $ 31,473 Real estate construction: Commercial Real Estate business line (a) 6 — — 6 — 3,038 3,044 Other business lines (b) — 7 — 7 — 404 411 Total real estate construction 6 7 — 13 — 3,442 3,455 Commercial mortgage: Commercial Real Estate business line (a) 9 — — 9 2 2,165 2,176 Other business lines (b) 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 December 31, 2018 Business loans: Commercial $ 34 $ 26 $ 8 $ 68 $ 141 $ 31,767 $ 31,976 Real estate construction: Commercial Real Estate business line (a) 6 — — 6 — 2,681 2,687 Other business lines (b) 6 — — 6 — 384 390 Total real estate construction 12 — — 12 — 3,065 3,077 Commercial mortgage: Commercial Real Estate business line (a) 4 — — 4 2 1,737 1,743 Other business lines (b) 32 5 8 45 18 7,300 7,363 Total commercial mortgage 36 5 8 49 20 9,037 9,106 Lease financing — — — — 2 505 507 International — — — — 3 1,010 1,013 Total business loans 82 31 16 129 166 45,384 45,679 Retail loans: Residential mortgage 11 3 — 14 36 1,920 1,970 Consumer: Home equity 4 1 — 5 19 1,741 1,765 Other consumer 1 — — 1 — 748 749 Total consumer 5 1 — 6 19 2,489 2,514 Total retail loans 16 4 — 20 55 4,409 4,484 Total loans $ 98 $ 35 $ 16 $ 149 $ 221 $ 49,793 $ 50,163 (a) Primarily loans to real estate developers. (b) Primarily loans secured by owner-occupied real estate.
Loans By Credit Quality Indicator	The following table presents loans by credit quality indicator, 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. Internally Assigned Rating (in millions) Pass (a) Special Mention (b) Substandard (c) Nonaccrual (d) Total December 31, 2019 Business loans: Commercial $ 29,785 $ 841 $ 699 $ 148 $ 31,473 Real estate construction: Commercial Real Estate business line (e) 3,013 19 12 — 3,044 Other business lines (f) 411 — — — 411 Total real estate construction 3,424 19 12 — 3,455 Commercial mortgage: Commercial Real Estate business line (e) 2,121 12 41 2 2,176 Other business lines (f) 7,141 147 83 12 7,383 Total commercial mortgage 9,262 159 124 14 9,559 Lease financing 579 7 2 — 588 International 972 29 8 — 1,009 Total business loans 44,022 1,055 845 162 46,084 Retail loans: Residential mortgage 1,823 2 — 20 1,845 Consumer: Home equity 1,682 1 11 17 1,711 Other consumer 722 6 1 — 729 Total consumer 2,404 7 12 17 2,440 Total retail loans 4,227 9 12 37 4,285 Total loans $ 48,249 $ 1,064 $ 857 $ 199 $ 50,369 December 31, 2018 Business loans: Commercial $ 30,817 $ 464 $ 554 $ 141 $ 31,976 Real estate construction: Commercial Real Estate business line (e) 2,664 23 — — 2,687 Other business lines (f) 382 8 — — 390 Total real estate construction 3,046 31 — — 3,077 Commercial mortgage: Commercial Real Estate business line (e) 1,682 14 45 2 1,743 Other business lines (f) 7,157 118 70 18 7,363 Total commercial mortgage 8,839 132 115 20 9,106 Lease financing 500 3 2 2 507 International 996 4 10 3 1,013 Total business loans 44,198 634 681 166 45,679 Retail loans: Residential mortgage 1,931 3 — 36 1,970 Consumer: Home equity 1,738 — 8 19 1,765 Other consumer 748 1 — — 749 Total consumer 2,486 1 8 19 2,514 Total retail loans 4,417 4 8 55 4,484 Total loans $ 48,615 $ 638 $ 689 $ 221 $ 50,163 (a) Includes all loans not included in the categories of special mention, substandard or nonaccrual. (b) Special mention loans are accruing loans that 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. This category is generally consistent with the "special mention" category as defined by regulatory authorities. (c) Substandard loans are accruing loans that 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 also are distinguished by the distinct possibility of loss in the future if these weaknesses are not corrected. This category is generally consistent with the "substandard" category as defined by regulatory authorities. (d) 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. A significant majority of nonaccrual loans are generally consistent with the "substandard" category and the remainder are generally consistent with the "doubtful" category as defined by regulatory authorities. (e) Primarily loans to real estate developers. (f) Primarily loans secured by owner-occupied real estate.
Schedule Of Nonaccrual, Reduced-Rate Loans And Foreclosed Property	The following table summarizes nonperforming assets. (in millions) December 31, 2019 December 31, 2018 Nonaccrual loans $ 199 $ 221 Reduced-rate loans (a) 5 8 Total nonperforming loans 204 229 Foreclosed property 11 1 Total nonperforming assets $ 215 $ 230 (a) Comprised of reduced-rate retail loans.
Changes In The Allowance For Loan Losses And Related Loan Amounts	The following table details the changes in the allowance for loan losses and related loan amounts. 2019 2018 2017 (dollar amounts in millions) Business Loans Retail Loans Total Business Loans Retail Loans Total Business Loans Retail Loans Total Years Ended December 31 Allowance for loan losses: Balance at beginning of period $ 627 $ 44 $ 671 $ 661 $ 51 $ 712 $ 682 $ 48 $ 730 Loan charge-offs (147 ) (5 ) (152 ) (99 ) (4 ) (103 ) (143 ) (6 ) (149 ) Recoveries on loans previously charged-off 40 5 45 47 5 52 50 7 57 Net loan (charge-offs) recoveries (107 ) — (107 ) (52 ) 1 (51 ) (93 ) 1 (92 ) Provision for loan losses 81 (8 ) 73 19 (8 ) 11 71 2 73 Foreign currency translation adjustment — — — (1 ) — (1 ) 1 — 1 Balance at end of period $ 601 $ 36 $ 637 $ 627 $ 44 $ 671 $ 661 $ 51 $ 712 As a percentage of total loans 1.30 % 0.84 % 1.27 % 1.37 % 0.97 % 1.34 % 1.48 % 1.12 % 1.45 % December 31 Allowance for loan losses: Individually evaluated for impairment $ 31 $ — $ 31 $ 27 $ — $ 27 $ 67 $ — $ 67 Collectively evaluated for impairment 570 36 606 600 44 644 594 51 645 Total allowance for loan losses $ 601 $ 36 $ 637 $ 627 $ 44 $ 671 $ 661 $ 51 $ 712 Loans: Individually evaluated for impairment $ 199 $ 16 $ 215 $ 240 $ 36 $ 276 $ 443 $ 34 $ 477 Collectively evaluated for impairment 45,885 4,269 50,154 45,439 4,448 49,887 44,188 4,508 48,696 Total loans evaluated for impairment $ 46,084 $ 4,285 $ 50,369 $ 45,679 $ 4,484 $ 50,163 $ 44,631 $ 4,542 $ 49,173
Changes In the Allowance For Credit Losses On Lending-Related Commitments	Changes in the allowance for credit losses on lending-related commitments, included in accrued expenses and other liabilities on the Consolidated Balance Sheets, are summarized in the following table. (in millions) Years Ended December 31 2019 2018 2017 Balance at beginning of period $ 30 $ 42 $ 41 Provision for credit losses on lending-related commitments 1 (12 ) 1 Balance at end of period $ 31 $ 30 $ 42
Individually Evaluated Impaired Loans	The following table presents additional information regarding individually evaluated impaired loans. Recorded Investment In: (in millions) Impaired Loans with No Related Allowance Impaired Loans with Related Allowance Total Impaired Loans Unpaid Principal Balance Related Allowance for Loan Losses December 31, 2019 Business loans: Commercial $ 30 $ 120 $ 150 $ 251 $ 30 Commercial mortgage: Commercial Real Estate business line (a) 39 — 39 49 — Other business lines (b) 1 9 10 15 1 Total commercial mortgage 40 9 49 64 1 Total business loans 70 129 199 315 31 Retail loans: Residential mortgage 8 — 8 8 — Consumer: Home equity 8 — 8 10 — Total retail loans (c) 16 — 16 18 — Total individually evaluated impaired loans $ 86 $ 129 $ 215 $ 333 $ 31 December 31, 2018 Business loans: Commercial $ 50 $ 130 $ 180 $ 227 $ 24 Commercial mortgage: Commercial Real Estate business line (a) 39 — 39 49 — Other business lines (b) 2 16 18 23 3 Total commercial mortgage 41 16 57 72 3 International 2 1 3 8 — Total business loans 93 147 240 307 27 Retail loans: Residential mortgage 16 8 24 25 — Consumer: Home equity 11 — 11 13 — Other consumer 1 — 1 1 — Total consumer 12 — 12 14 — Total retail loans (c) 28 8 36 39 — Total individually evaluated impaired loans $ 121 $ 155 $ 276 $ 346 $ 27 (a) Primarily loans to real estate developers. (b) Primarily loans secured by owner-occupied real estate. (c) Individually evaluated retail loans generally have no related allowance for loan losses, primarily due to policy which results in direct write-downs of most restructured retail loans.
Average Individually Evaluated Impaired Loans And Related Interest Recognized	The following table presents information regarding average individually evaluated impaired loans and the related interest recognized. Interest income recognized for the period primarily related to performing restructured loans. Individually Evaluated Impaired Loans 2019 2018 2017 (in millions) Average Balance for the Period Interest Income Recognized for the Period Average Balance for the Period Interest Income Recognized for the Period Average Balance for the Period Interest Income Recognized for the Period Years Ended December 31 Business loans: Commercial $ 156 $ 2 $ 262 $ 5 $ 451 $ 8 Commercial mortgage: Commercial Real Estate business line (a) 39 3 40 4 21 2 Other business lines (b) 14 1 23 — 31 — Total commercial mortgage 53 4 63 4 52 2 Lease financing 1 — — — — — International 2 — 4 — 8 — Total business loans 212 6 329 9 511 10 Retail loans: Residential mortgage 21 1 21 — 24 — Consumer: Home equity 9 — 11 — 13 — Other consumer — — 1 — 3 — Total consumer 9 — 12 — 16 — Total retail loans 30 1 33 — 40 — Total individually evaluated impaired loans $ 242 $ 7 $ 362 $ 9 $ 551 $ 10 (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 tables detail the recorded balance at December 31, 2019 and 2018 of loans considered to be TDRs that were restructured during the years ended December 31, 2019 and 2018 , 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. 2019 2018 Type of Modification Type of Modification (in millions) Principal Deferrals (a) Interest Rate Reductions Total Modifications Principal Deferrals (a) Interest Rate Reductions Total Modifications Years Ended December 31 Business loans: Commercial $ 28 $ — $ 28 $ 27 $ — $ 27 Commercial mortgage: Other business lines (b) — — — 2 — 2 International — — — 1 — 1 Total business loans 28 — 28 30 — 30 Retail loans: Consumer: Home equity (c) — 1 1 — 3 3 Total loans $ 28 $ 1 $ 29 $ 30 $ 3 $ 33 (a) Primarily represents loan balances where terms were extended 90 days or more at or above contractual interest rates. Also includes commercial loans restructured in bankruptcy. (b) Primarily loans secured by owner-occupied real estate. (c) Includes bankruptcy loans for which the court has discharged the borrower's obligation and the borrower has not reaffirmed the debt.

Significant Group Concentrati_2

Significant Group Concentrations of Credit Risk Significant Group Concentrations of Credit Risk (Tables)	12 Months Ended
	Dec. 31, 2019
Significant Group Concentrations of Credit Risk [Abstract]
Schedule of Automotive Industry Outstanding Loans and Total Exposure	Outstanding loans, included in commercial loans on the Consolidated Balance Sheets, and total exposure (outstanding loans, unused commitments and standby letters of credit) to companies related to the automotive industry were as follows: (in millions) December 31 2019 2018 Automotive loans: Production $ 1,249 $ 1,331 Dealer 7,414 8,097 Total automotive loans $ 8,663 $ 9,428 Total automotive exposure: Production $ 2,358 $ 2,396 Dealer 9,677 10,044 Total automotive exposure $ 12,035 $ 12,440
Schedule of Commercial Real Estate Loans and Unused Commitments	Further, the Corporation’s portfolio of commercial real estate loans, which includes real estate construction and commercial mortgage loans, was as follows. (in millions) December 31 2019 2018 Real estate construction loans: Commercial Real Estate business line (a) $ 3,044 $ 2,687 Other business lines (b) 411 390 Total real estate construction loans 3,455 3,077 Commercial mortgage loans: Commercial Real Estate business line (a) 2,176 1,743 Other business lines (b) 7,383 7,363 Total commercial mortgage loans 9,559 9,106 Total commercial real estate loans $ 13,014 $ 12,183 Total unused commitments on commercial real estate loans $ 3,557 $ 3,146 (a) Primarily loans to real estate developers. (b) Primarily loans secured by owner-occupied real estate.

Premises and Equipment (Tables)

Premises and Equipment (Tables)	12 Months Ended
	Dec. 31, 2019
Premises and Equipments [Abstract]
Premises and Equipment	A summary of premises and equipment by major category follows: (in millions) December 31 2019 2018 Land $ 86 $ 85 Buildings and improvements 818 842 Furniture and equipment 513 492 Total cost 1,417 1,419 Less: Accumulated depreciation and amortization (960 ) (944 ) Net book value $ 457 $ 475

Derivative And Credit-Related_2

Derivative And Credit-Related Financial Instruments (Tables)	12 Months Ended
	Dec. 31, 2019
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 December 31, 2019 and 2018 . The table excludes commitments and warrants accounted for as derivatives. December 31, 2019 December 31, 2018 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 $ 3,325 $ — $ — $ 2,625 $ — $ 2 Swaps - cash flow - receive fixed/ pay floating 4,550 — — — — — Derivatives used as economic hedges Foreign exchange contracts: Spot, forwards and swaps 330 — 2 302 1 1 Total risk management purposes 8,205 — 2 2,927 1 3 Customer-initiated and other activities Interest rate contracts: Caps and floors written 671 — — 885 — 1 Caps and floors purchased 671 — — 885 1 — Swaps 16,485 211 39 13,115 66 67 Total interest rate contracts 17,827 211 39 14,885 67 68 Energy contracts: Caps and floors written 477 — 23 278 — 26 Caps and floors purchased 477 23 — 278 26 — Swaps 2,135 73 69 2,094 163 160 Total energy contracts 3,089 96 92 2,650 189 186 Foreign exchange contracts: Spot, forwards, options and swaps 1,013 10 8 1,095 18 12 Total customer-initiated and other activities 21,929 317 139 18,630 274 266 Total gross derivatives $ 30,134 317 141 $ 21,557 275 269 Amounts offset in the Consolidated Balance Sheets: Netting adjustment - Offsetting derivative assets/liabilities (63 ) (63 ) (45 ) (45 ) Netting adjustment - Cash collateral received/posted (11 ) (12 ) (174 ) (1 ) Net derivatives included in the Consolidated Balance Sheets (b) 243 66 56 223 Amounts not offset in the Consolidated Balance Sheets: Marketable securities pledged under bilateral collateral agreements — (21 ) (1 ) — Net derivatives after deducting amounts not offset in the Consolidated Balance Sheets $ 243 $ 45 $ 55 $ 223 (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 on 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 $9 million and $2 million at December 31, 2019 and 2018 , respectively.
Schedule of Effects of Fair Value Hedging on the Consolidated Statements of Comprehensive Income	(in millions) Interest on Medium- and Long-Term Debt Years Ended December 31 2019 2018 Total interest on medium-and long-term debt (a) $ 197 $ 144 Fair value hedging relationships: Interest rate contracts: Hedged items 110 74 Derivatives designated as hedging instruments (4 ) (7 ) (a) Includes the effects of hedging.
Schedule Of Weighted Average Maturity And Interest Rates On Risk Management Interest Rate Swaps	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 December 31, 2019 and 2018 . Weighted Average (dollar amounts in millions) Derivative Notional Amount Carrying Value of Hedged Items (a) Remaining Maturity (in years) Receive Rate Pay Rate (b) December 31, 2019 Swaps - cash flow - receive fixed/pay floating rate Variable rate loans $ 4,550 3.0 1.94 % 1.71 % Swaps - fair value - receive fixed/pay floating rate Medium- and long-term debt 3,325 $ 3,469 4.6 3.44 2.80 December 31, 2018 Swaps - fair value - receive fixed/pay floating rate Medium- and long-term debt 2,625 2,663 3.9 3.40 3.45 (a) Included $146 million and $49 million of cumulative hedging adjustments at December 31, 2019 and 2018 , respectively, which included $7 million and $8 million , respectively, of hedging adjustment on a discontinued hedging relationship. (b) Variable rates paid on receive fixed swaps designated as fair value and cash flow hedges are based on one- and six-month LIBOR rates in effect at December 31, 2019 and 2018 .
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: (in millions) Years Ended December 31 Location of Gain 2019 2018 Interest rate contracts Other noninterest income $ 29 $ 26 Energy contracts Other noninterest income 5 4 Foreign exchange contracts Foreign exchange income 43 47 Total $ 77 $ 77
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) December 31 2019 2018 Unused commitments to extend credit: Commercial and other $ 23,681 $ 24,266 Bankcard, revolving check credit and home equity loan commitments 3,180 3,001 Total unused commitments to extend credit $ 26,861 $ 27,267 Standby letters of credit $ 3,320 $ 3,244 Commercial letters of credit 18 39
Summary Of Criticized Letters Of Credit	The following table presents a summary of criticized standby and commercial letters of credit at December 31, 2019 and 2018 . The Corporation's criticized list is 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) December 31, 2019 December 31, 2018 Total criticized standby and commercial letters of credit $ 44 $ 49 As a percentage of total outstanding standby and commercial letters of credit 1.3 % 1.5 %

Goodwill and Intangible Assets

Goodwill and Intangible Assets Goodwill and Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
Summary of Changes in Carrying Value of Goodwill	The following table summarizes the carrying value of goodwill by reporting unit for the years ended December 31, 2019 and 2018 . (in millions) December 31 2019 2018 Business Bank $ 473 $ 473 Retail Bank 101 101 Wealth Management 61 61 Total $ 635 $ 635
Summary of Core Deposit Intangible Carrying Value and Amortization	A summary of core deposit intangible carrying value and related accumulated amortization follows: (in millions) December 31 2019 2018 Gross carrying amount $ 34 $ 34 Accumulated amortization (32 ) (30 ) Net carrying amount $ 2 $ 4
Schedule of Core Deposit Intangible Estimated Future Amortization Expense	At December 31, 2019 , estimated future amortization expense was as follows: (in millions) Years Ending December 31 2020 $ 1 2021 1 Total $ 2

Net Income Per Common Share (Ta

Net Income Per Common Share (Tables)	12 Months Ended
	Dec. 31, 2019
Earnings Per Share [Abstract]
Basic And Diluted Net Income Per Common Share	Basic and diluted net income per common share are presented in the following table. (in millions, except per share data) Years Ended December 31 2019 2018 2017 Basic and diluted Net income $ 1,198 $ 1,235 $ 743 Less: Income allocated to participating securities 7 8 5 Net income attributable to common shares $ 1,191 $ 1,227 $ 738 Basic average common shares 150 168 174 Basic net income per common share $ 7.95 $ 7.31 $ 4.23 Basic average common shares 150 168 174 Dilutive common stock equivalents: Net effect of the assumed exercise of stock options 1 2 3 Net effect of the assumed exercise of warrants — 1 1 Diluted average common shares 151 171 178 Diluted net income per common share $ 7.87 $ 7.20 $ 4.14
Schedule of Average Shares Excluded From Diluted Net Income Per Common Share Computation	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. There were no anti-dilutive options for the year ended December 31, 2017. Years Ended December 31 2019 2018 Average outstanding options 542,786 193,248 Range of exercise prices $67.53 - $95.25 $95.25

Variable Interest Entities (V_2

Variable Interest Entities (VIEs) (Tables)	12 Months Ended
	Dec. 31, 2019
Variable Interest Entity, Not Primary Beneficiary, Disclosures [Abstract]
Impact of VIEs on the Consolidated Statements of Income	The following table summarizes the impact of these tax credit entities on line items on the Corporation’s Consolidated Statements of Income. (in millions) Years Ended December 31 2019 2018 2017 Other noninterest income: Sales of other tax credit investments $ 2 $ 5 $ 2 Provision for income taxes: Amortization of LIHTC Investments 65 65 67 Low income housing tax credits (62 ) (62 ) (63 ) Other tax benefits related to tax credit entities (13 ) (14 ) (24 ) Total provision for income taxes $ (10 ) $ (11 ) $ (20 )

Deposits (Tables)

Deposits (Tables)	12 Months Ended
	Dec. 31, 2019
Deposits [Abstract]
Schedule Of Maturities Of Certificates of Deposit and Other Deposits with a Stated Maturity	At December 31, 2019 , the scheduled maturities of certificates of deposit and other deposits with a stated maturity were as follows: (in millions) Years Ending December 31 2020 $ 2,970 2021 156 2022 24 2023 15 2024 11 Thereafter 26 Total $ 3,202
Schedule Of Maturities Of Domestic Deposits Of $100,000 Or More	A maturity distribution of domestic certificates of deposit of $100,000 and over follows: (in millions) December 31 2019 2018 Three months or less $ 398 $ 363 Over three months to six months 503 146 Over six months to twelve months 819 278 Over twelve months 97 297 Total $ 1,817 $ 1,084

Short-term Borrowings Short-ter

Short-term Borrowings Short-term Borrowings (Tables)	12 Months Ended
	Dec. 31, 2019
Short-term Debt [Abstract]
Summary of Short-term Borrowings	The following table provides a summary of short-term borrowings. (dollar amounts in millions) Federal Funds Purchased and Securities Sold Under Agreements to Repurchase Other Short-term Borrowings December 31, 2019 Amount outstanding at year-end $ 71 $ — Weighted average interest rate at year-end 1.50 % — % Maximum month-end balance during the year $ 835 $ 1,200 Average balance outstanding during the year 113 256 Weighted average interest rate during the year 2.28 % 2.44 % December 31, 2018 Amount outstanding at year-end $ 44 $ — Weighted average interest rate at year-end 2.39 % — % Maximum month-end balance during the year $ 182 $ 250 Average balance outstanding during the year 59 3 Weighted average interest rate during the year 1.91 % 1.75 % December 31, 2017 Amount outstanding at year-end $ 10 $ — Weighted average interest rate at year-end 1.43 % — % Maximum month-end balance during the year $ 41 $ 1,024 Average balance outstanding during the year 20 257 Weighted average interest rate during the year 1.02 % 1.15 %

Medium- And Long-Term Debt (Tab

Medium- And Long-Term Debt (Tables)	12 Months Ended
	Dec. 31, 2019
Debt Disclosure [Abstract]
Schedule Of Medium- And Long-Term Debt	Medium- and long-term debt is summarized as follows: (in millions) December 31 2019 2018 Parent company Subordinated notes: 3.80% subordinated notes due 2026 (a) $ 264 $ 250 Medium- and long-term notes: 2.125% notes due 2019 (a) — 348 3.70% notes due 2023 (a) 884 861 4.00% notes due 2029 (a) 587 — Total medium- and long-term notes 1,471 1,209 Total parent company 1,735 1,459 Subsidiaries Subordinated notes: 4.00% subordinated notes due 2025 (a) 360 343 7.875% subordinated notes due 2026 (a) 202 198 Total subordinated notes 562 541 Medium- and long-term notes: 2.50% notes due 2020 (a) 674 663 2.50% notes due 2024 (a) 498 — Total medium- and long-term notes 1,172 663 Federal Home Loan Bank (FHLB) advances: Floating-rate based on FHLB auction rate due 2026 2,800 2,800 Floating-rate based on FHLB auction rate due 2028 1,000 1,000 Total FHLB advances 3,800 3,800 Total subsidiaries 5,534 5,004 Total medium- and long-term debt $ 7,269 $ 6,463 (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.
Schedule of Maturities of Medium- and Long-term Debt	At December 31, 2019 , the principal maturities of medium- and long-term debt were as follows: (in millions) Years Ending December 31 2020 $ 675 2021 — 2022 — 2023 850 2024 500 Thereafter 5,100 Total $ 7,125

Accumulated Other Comprehensi_2

Accumulated Other Comprehensive Loss (Tables)	12 Months Ended
	Dec. 31, 2019
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Schedule Of Accumulated Other Comprehensive Income (Loss)	The following table presents a reconciliation of the changes in the components of accumulated other comprehensive loss and details the components of other comprehensive income (loss) for the years ended December 31, 2019 , 2018 and 2017 , including the amount of income tax expense (benefit) allocated to each component of other comprehensive income (loss). (in millions) Years Ended December 31 2019 2018 2017 Accumulated net unrealized gains (losses) on investment securities: Balance at beginning of period, net of tax $ (138 ) $ (101 ) $ (33 ) Cumulative effect of change in accounting principle — 1 — Net unrealized holding gains (losses) arising during the period 257 (69 ) (81 ) Less: Provision (benefit) for income taxes 60 (16 ) (27 ) Net unrealized holding gains (losses) arising during the period, net of tax 197 (53 ) (54 ) Less: Net realized losses included in net securities losses (8 ) (20 ) — Less: Benefit for income taxes (2 ) (5 ) — Reclassification adjustment for net securities losses included in net income, net of tax (6 ) (15 ) — Less: Net losses realized as a yield adjustment in interest on investment securities — — (3 ) Less: Benefit for income taxes — — (1 ) Reclassification adjustment for net losses realized as a yield adjustment included in net income, net of tax — — (2 ) Change in net unrealized gains (losses) on investment securities, net of tax 203 (38 ) (52 ) Reclassification of certain deferred tax effects (a) — — (16 ) Balance at end of period, net of tax $ 65 $ (138 ) $ (101 ) Accumulated net gains on cash flow hedges: Balance at beginning of period, net of tax $ — $ — $ — Net cash flow hedge gains arising during the period 44 — — Less: Provision for income taxes 10 — — Change in net cash flow hedge gains, net of tax 34 — — Balance at end of period, net of tax (b) $ 34 $ — $ — Accumulated defined benefit pension and other postretirement plans adjustment: Balance at beginning of period, net of tax $ (471 ) $ (350 ) $ (350 ) Actuarial gain (loss) arising during the period 163 (191 ) 72 Less: Provision (benefit) for income taxes 38 (44 ) 17 Net defined benefit pension and other postretirement adjustment arising during the period, net of tax 125 (147 ) 55 Amounts recognized in other noninterest expense: Amortization of actuarial net loss 42 61 51 Amortization of prior service credit (27 ) (27 ) (27 ) Total amounts recognized in other noninterest expense 15 34 24 Less: Provision for income taxes 3 8 8 Adjustment for amounts recognized as other components of net benefit cost during the period, net of tax 12 26 16 Change in defined benefit pension and other postretirement plans adjustment, net of tax 137 (121 ) 71 Reclassification of certain deferred tax effects (a) — — (71 ) Balance at end of period, net of tax $ (334 ) $ (471 ) $ (350 ) Total accumulated other comprehensive loss at end of period, net of tax $ (235 ) $ (609 ) $ (451 ) (a) Amounts reclassified to retained earnings due to early adoption of ASU 2018-02. For further information, refer to Note 1. (b) The corporation expects to reclassify $12 million of net gains, net of tax, from accumulated other comprehensive loss to earnings over the next twelve months if interest yield curves and notional amounts remain at December 31, 2019 levels.

Share-Based Compensation Share-

Share-Based Compensation Share-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2019
Share-based Payment Arrangement, Noncash Expense [Abstract]
Summary of Components of Share-Based Compensation Expense	The components of share-based compensation expense for all share-based compensation plans and related tax benefits are as follows: (in millions) Years Ended December 31 2019 2018 2017 Total share-based compensation expense $ 39 $ 48 $ 39 Related tax benefits recognized in net income $ 9 $ 11 $ 14
Schedule of Unrecognized Compensation Expense	The following table summarizes unrecognized compensation expense for all share-based plans. (dollar amounts in millions) December 31, 2019 Total unrecognized share-based compensation expense $ 33 Weighted-average expected recognition period (in years) 2.3
Estimated Weighted-Average Grant-Date Fair Value per Option and the Underlying Model Assumptions	The estimated weighted-average grant-date fair value per option and the underlying binomial option-pricing model assumptions are summarized in the following table: Years Ended December 31 2019 2018 2017 Weighted-average grant-date fair value per option $ 22.27 $ 30.32 $ 19.61 Weighted-average assumptions: Risk-free interest rates 2.74 % 2.63 % 2.47 % Expected dividend yield 3.00 3.00 3.00 Expected volatility factors of the market price of Comerica common stock 30 36 34 Expected option life (in years) 7.6 7.4 7.0
Summary of Stock Option Activity and Related Information	A summary of the Corporation’s stock option activity and related information for the year ended December 31, 2019 follows: Weighted-Average Number of Options (in thousands) Exercise Price per Share Remaining Contractual Term (in years) Aggregate Intrinsic Value (in millions) Outstanding-January 1, 2019 2,943 $ 44.70 Granted 283 80.14 Forfeited or expired (35 ) 65.91 Exercised (511 ) 37.32 Outstanding-December 31, 2019 2,680 49.58 5.3 $ 66 Exercisable-December 31, 2019 1,816 $ 41.79 4.2 $ 56
Summary of Restricted Stock Activity and Related Information	A summary of the Corporation’s restricted stock activity and related information for the year ended December 31, 2019 follows: Number of Shares (in thousands) Weighted-Average Grant-Date Fair Value per Share Outstanding-January 1, 2019 869 $ 44.34 Forfeited (27 ) 49.81 Vested (384 ) 38.81 Outstanding-December 31, 2019 458 $ 48.64
Summary of Restricted Stock Unit Activity and Related Information	A summary of the Corporation's restricted stock unit activity and related information for the year ended December 31, 2019 follows: Service-Based Units Performance-Based Units Number of Units (in thousands) Weighted-Average Grant-Date Fair Value per Share Number of Units (in thousands) Weighted-Average Grant-Date Fair Value per Share Outstanding-January 1, 2019 367 $ 68.14 662 $ 56.64 Granted 237 78.81 329 66.80 Forfeited (14 ) 87.38 (28 ) 81.06 Vested (12 ) 55.81 (420 ) 32.53 Outstanding-December 31, 2019 578 72.34 543 80.22

Employee Benefit Plans (Tables)

Employee Benefit Plans (Tables)	12 Months Ended
	Dec. 31, 2019
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Abstract]
Schedule of Defined Benefit Plans Disclosures	The following table sets forth reconciliations of plan assets and the projected benefit obligation, the weighted-average assumptions used to determine year-end benefit obligations, and the amounts recognized in accumulated other comprehensive income (loss) for the Corporation’s defined benefit pension plans and postretirement benefit plan at December 31, 2019 and 2018 . The Corporation used a measurement date of December 31, 2019 for these plans. Defined Benefit Pension Plans Qualified Non-Qualified Postretirement Benefit Plan (dollar amounts in millions) 2019 2018 2019 2018 2019 2018 Change in fair value of plan assets: Fair value of plan assets at January 1 $ 2,458 $ 2,747 $ — $ — $ 56 $ 60 Actual return on plan assets 579 (167 ) — — 5 (1 ) Employer contributions — — — — 1 1 Benefits paid (104 ) (122 ) — — (5 ) (4 ) Fair value of plan assets at December 31 $ 2,933 $ 2,458 $ — $ — $ 57 $ 56 Change in projected benefit obligation: Projected benefit obligation at January 1 $ 1,901 $ 2,061 $ 211 $ 212 $ 46 $ 51 Service cost 31 29 3 2 — — Interest cost 80 75 9 8 2 2 Actuarial loss (gain) 223 (142 ) 25 — 5 (3 ) Benefits paid (104 ) (122 ) (13 ) (11 ) (5 ) (4 ) Projected benefit obligation at December 31 $ 2,131 $ 1,901 $ 235 $ 211 $ 48 $ 46 Accumulated benefit obligation $ 2,121 $ 1,893 $ 234 $ 209 $ 48 $ 46 Funded status at December 31 (a) (b) $ 802 $ 557 $ (235 ) $ (211 ) $ 9 $ 10 Weighted-average assumptions used: Discount rate 3.43 % 4.37 % 3.43 % 4.37 % 3.26 % 4.26 % Rate of compensation increase 4.00 4.00 4.00 4.00 n/a n/a Healthcare cost trend rate: Cost trend rate assumed for next year n/a n/a n/a n/a 6.25 6.50 Rate to which the cost trend rate is assumed to decline (the ultimate trend rate) n/a n/a n/a n/a 4.50 4.50 Year when rate reaches the ultimate trend rate n/a n/a n/a n/a 2027 2027 Amounts recognized in accumulated other comprehensive income (loss) before income taxes: Net actuarial loss $ (463 ) $ (687 ) $ (94 ) $ (76 ) $ (20 ) $ (19 ) Prior service credit 121 140 26 34 1 1 Balance at December 31 $ (342 ) $ (547 ) $ (68 ) $ (42 ) $ (19 ) $ (18 ) (a) Based on projected benefit obligation for defined benefit pension plans and accumulated benefit obligation for postretirement benefit plan. (b) The Corporation recognizes the overfunded and underfunded status of the plans in accrued income and other assets and accrued expenses and other liabilities, respectively, on the Consolidated Balance Sheets. n/a - not applicable
Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income (Loss)	The following table details the changes in plan assets and benefit obligations recognized in other comprehensive income (loss) for the year ended December 31, 2019 . Defined Benefit Pension Plans (in millions) Qualified Non-Qualified Postretirement Benefit Plan Total Actuarial gain (loss) arising during the period $ 190 $ (25 ) $ (2 ) $ 163 Amortization of net actuarial loss 34 7 1 42 Amortization of prior service credit (19 ) (8 ) — (27 ) Total recognized in other comprehensive income (loss) $ 205 $ (26 ) $ (1 ) $ 178
Components of Net Periodic Defined Benefit Cost	Components of net periodic defined benefit cost and postretirement benefit cost, the actual return on plan assets and the weighted-average assumptions used were as follows: Defined Benefit Pension Plans (dollar amounts in millions) Qualified Non-Qualified Years Ended December 31 2019 2018 2017 2019 2018 2017 Service cost (a) $ 31 $ 29 $ 29 $ 3 $ 2 $ 2 Other components of net benefit (credit) cost: Interest cost 80 75 78 9 8 8 Expected return on plan assets (166 ) (165 ) (159 ) — — — Amortization of prior service credit (19 ) (19 ) (19 ) (8 ) (8 ) (8 ) Amortization of net loss 34 51 43 7 9 8 Total other components of net benefit (credit) cost (b) (71 ) (58 ) (57 ) 8 9 8 Net periodic defined benefit (credit) cost $ (40 ) $ (29 ) $ (28 ) $ 11 $ 11 $ 10 Actual return on plan assets $ 579 $ (167 ) $ 396 n/a n/a n/a Actual rate of return on plan assets 24.07 % (6.21 )% 16.48 % n/a n/a n/a Weighted-average assumptions used: Discount rate 4.37 % 3.74 % 4.23 % 4.37 % 3.74 % 4.23 % Expected long-term return on plan assets 6.50 6.50 6.50 n/a n/a n/a Rate of compensation increase 4.00 3.75 3.50 4.00 3.75 3.50 (a) Included in salaries and benefits expense on the Consolidated Statements of Income. (b) Included in other noninterest expenses on the Consolidated Statements of Income. n/a - not applicable (dollar amounts in millions) Postretirement Benefit Plan Years Ended December 31 2019 2018 2017 Other components of net benefit cost: Interest cost $ 2 $ 2 $ 2 Expected return on plan assets (3 ) (3 ) (3 ) Amortization of net loss 1 1 1 Net periodic postretirement benefit cost $ — $ — $ — Actual return on plan assets $ 5 $ (1 ) $ 2 Actual rate of return on plan assets 9.14 % (2.05 )% 3.52 % Weighted-average assumptions used: Discount rate 4.26 % 3.55 % 3.92 % Expected long-term return on plan assets 5.00 5.00 5.00 Healthcare cost trend rate: Cost trend rate assumed 6.50 6.50 6.50 Rate to which the cost trend rate is assumed to decline (the ultimate trend rate) 4.50 4.50 4.50 Year that the rate reaches the ultimate trend rate 2027 2027 2027
Balances Remaining in Accumulated Other Comprehensive Income (Loss) to be Recognized over Next Fiscal Year	The estimated portion of balances remaining in accumulated other comprehensive income (loss) that are expected to be recognized as a component of net periodic benefit cost in the year ended December 31, 2020 are as follows: Defined Benefit Pension Plans (in millions) Qualified Non-Qualified Postretirement Benefit Plan Total Net loss $ 54 $ 9 $ 1 $ 64 Prior service credit (19 ) (8 ) — (27 )
Fair Value of Defined Benefit Plan Investments	The fair values of the Corporation’s qualified defined benefit pension plan investments measured at fair value on a recurring basis at December 31, 2019 and 2018 , by asset category and level within the fair value hierarchy, are detailed in the table below. (in millions) Total Level 1 Level 2 Level 3 December 31, 2019 Equity securities: Mutual funds $ 2 $ 2 $ — $ — Common stock 1,086 1,086 — — Fixed income securities: U.S. Treasury and other U.S. government agency securities 574 551 23 — Corporate and municipal bonds and notes 734 — 734 — Mortgage-backed securities 27 — 27 — Private placements 57 — — 57 Total investments in the fair value hierarchy 2,480 $ 1,639 $ 784 $ 57 Investments measured at net asset value: Collective investment funds 469 Total investments at fair value $ 2,949 December 31, 2018 Equity securities: Mutual funds $ 3 $ 3 $ — $ — Common stock 803 803 — — Fixed income securities: U.S. Treasury and other U.S. government agency securities 496 482 14 — Corporate and municipal bonds and notes 679 — 679 — Mortgage-backed securities 29 — 29 — Private placements 60 — — 60 Total investments in the fair value hierarchy 2,070 $ 1,288 $ 722 $ 60 Investments measured at net asset value: Collective investment funds 392 Total investments at fair value $ 2,462
Changes in Level 3 Defined Benefit Plan Investments	The table below provides a summary of changes in the Corporation’s qualified defined benefit pension plan’s Level 3 investments measured at fair value on a recurring basis for the years ended December 31, 2019 and 2018 . Balance at Beginning of Period Balance at End of Period Net Gains (Losses) (in millions) Realized Unrealized Purchases Sales Year Ended December 31, 2019 Private placements $ 60 $ 3 $ 8 $ 49 $ (63 ) $ 57 Year Ended December 31, 2018 Private placements $ 80 $ (1 ) $ (7 ) $ 70 $ (82 ) $ 60
Estimated Future Benefit Payments	The Corporation currently expects to make no employer contributions to the qualified and non-qualified defined benefit pension plans and postretirement benefit plan for the year ended December 31, 2020 . Estimated Future Benefit Payments (in millions) Years Ended December 31 Qualified Defined Benefit Pension Plan Non-Qualified Defined Benefit Pension Plan Postretirement Benefit Plan (a) 2020 $ 134 $ 14 $ 5 2021 133 14 5 2022 136 14 5 2023 137 15 5 2024 139 15 4 2025 - 2029 683 74 16 (a) Estimated benefit payments in the postretirement benefit plan are net of estimated Medicare subsidies.

Income Taxes And Tax-Related _2

Income Taxes And Tax-Related Items Income Taxes And Tax-Related Items (Tables)	12 Months Ended
	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Current and Deferred Components of the Provision for Income Taxes	The current and deferred components of the provision for income taxes were as follows: (in millions) December 31 2019 2018 2017 Current: Federal $ 267 $ 227 $ 371 Foreign 7 10 5 State and local 48 39 36 Total current 322 276 412 Deferred: Federal 16 29 (26 ) State and local (4 ) 3 (2 ) Remeasurement of deferred taxes — (8 ) 107 Total deferred 12 24 79 Total $ 334 $ 300 $ 491
Reconciliation of Expected Income Tax Expense at the Federal Statutory Rate to the Provision for Income Taxes	A reconciliation of expected income tax expense at the federal statutory rate to the Corporation’s provision for income taxes and effective tax rate follows: (dollar amounts in millions) 2019 2018 2017 Years Ended December 31 Amount Rate Amount Rate Amount Rate Tax based on federal statutory rate $ 322 21.0 % $ 323 21.0 % $ 432 35.0 % State income taxes 33 2.2 35 2.3 22 1.8 Employee stock transactions (12 ) (0.8 ) (23 ) (1.5 ) (35 ) (2.8 ) Capitalization and recovery positions (a) — — (17 ) (1.1 ) — — Affordable housing and historic credits (11 ) (0.7 ) (12 ) (0.8 ) (21 ) (1.7 ) Bank-owned life insurance (9 ) (0.6 ) (9 ) (0.6 ) (16 ) (1.3 ) Remeasurement of deferred taxes — — (8 ) (0.5 ) 107 8.7 FDIC insurance expense (b) 5 0.3 8 0.5 — — Other changes in unrecognized tax benefits — — 4 0.3 — — Tax-related interest and penalties 2 0.1 (3 ) (0.2 ) 4 0.3 Lease termination transactions — — — — (2 ) (0.2 ) Other 4 0.2 2 0.1 — — Provision for income taxes $ 334 21.7 % $ 300 19.5 % $ 491 39.8 % (a) Tax benefits from the review of tax capitalization and recovery positions related to software and fixed assets included in the 2017 tax return. (b) Beginning January 1, 2018, FDIC insurance expense is no longer deductible as a result of the enactment of the Tax Cuts and Jobs Act.
Reconciliation of Beginning and Ending Unrecognized Tax Benefits	A reconciliation of the beginning and ending amount of net unrecognized tax benefits follows: (in millions) 2019 2018 2017 Balance at January 1 $ 14 $ 10 $ 15 Increase as a result of tax positions taken during a prior period 4 9 4 Decrease related to settlements with tax authorities (1 ) (4 ) (8 ) Other — (1 ) (1 ) Balance at December 31 $ 17 $ 14 $ 10
Tax Years Remaining Open for Examination for Significant Tax Jurisdictions	The following tax years for significant jurisdictions remain subject to examination as of December 31, 2019 : Jurisdiction Tax Years Federal 2014-2018 California 2006-2017
Principal Components of Deferred Tax Assets and Liabilities	The principal components of deferred tax assets and liabilities were as follows: (in millions) December 31 2019 2018 Deferred tax assets: Allowance for loan losses $ 134 $ 141 Deferred compensation 61 68 Deferred loan origination fees and costs 8 9 Net unrealized losses on investment securities available-for-sale — 42 Operating lease liability 77 — Other temporary differences, net 49 42 Total deferred tax asset before valuation allowance 329 302 Valuation allowance (3 ) (3 ) Total deferred tax assets 326 299 Deferred tax liabilities: Lease financing transactions (73 ) (74 ) Defined benefit plans (91 ) (41 ) Allowance for depreciation (21 ) (18 ) Hedging gains and losses (10 ) — Leasing right of use asset (69 ) — Net unrealized gains on investment securities available-for-sale (20 ) — Total deferred tax liabilities (284 ) (133 ) Net deferred tax asset $ 42 $ 166

Regulatory Capital and Reserv_2

Regulatory Capital and Reserve Requirements Regulatory Capital and Reserve Requirements (Tables)	12 Months Ended
	Dec. 31, 2019
Broker-Dealer, Net Capital Requirement, SEC Regulation [Abstract]
Summary of Capital Position	The following is a summary of the capital position of the Corporation and Comerica Bank, its principal banking subsidiary. (dollar amounts in millions) Comerica Incorporated (Consolidated) Comerica Bank December 31, 2019 CET1 capital (minimum $3.1 billion (Consolidated)) $ 6,919 $ 7,199 Tier 1 capital (minimum $4.1 billion (Consolidated)) 6,919 7,199 Total capital (minimum $5.5 billion (Consolidated)) 8,282 8,371 Risk-weighted assets 68,273 68,071 Average assets (fourth quarter) 72,773 72,564 CET1 capital to risk-weighted assets (minimum-4.5%) 10.13 % 10.58 % Tier 1 capital to risk-weighted assets (minimum-6.0%) 10.13 10.58 Total capital to risk-weighted assets (minimum-8.0%) 12.13 12.30 Tier 1 capital to average assets (minimum-4.0%) 9.51 9.92 Capital conservation buffer (minimum-2.5%) 4.13 4.30 December 31, 2018 CET1 capital (minimum $3.0 billion (Consolidated)) $ 7,470 $ 7,229 Tier 1 capital (minimum $4.0 billion (Consolidated)) 7,470 7,229 Total capital (minimum $5.4 billion (Consolidated)) 8,855 8,433 Risk-weighted assets 67,047 66,857 Average assets (fourth quarter) 71,070 70,905 CET1 capital to risk-weighted assets (minimum-4.5%) 11.14 % 10.81 % Tier 1 capital to risk-weighted assets (minimum-6.0%) 11.14 10.81 Total capital to risk-weighted assets (minimum-8.0%) 13.21 12.61 Tier 1 capital to average assets (minimum-4.0%) 10.51 10.20 Capital conservation buffer (minimum-2.5%) 5.14 4.61

Business Segment Information (T

Business Segment Information (Tables)	12 Months Ended
	Dec. 31, 2019
Segment Reporting [Abstract]
Business Segment Financial Results	Business segment financial results are as follows: (dollar amounts in millions) Business Bank Retail Bank Wealth Management Finance Other Total Year Ended December 31, 2019 Earnings summary: Net interest income (expense) $ 1,655 $ 568 $ 183 $ (126 ) $ 59 $ 2,339 Provision for credit losses 88 (4 ) (14 ) — 4 74 Noninterest income 555 132 270 43 10 1,010 Noninterest expenses 795 597 283 (1 ) 69 1,743 Provision (benefit) for income taxes 306 24 44 (26 ) (14 ) (a) 334 Net income (loss) $ 1,021 $ 83 $ 140 $ (56 ) $ 10 $ 1,198 Net credit-related charge-offs (recoveries) $ 111 $ 1 $ (5 ) $ — $ — $ 107 Selected average balances: Assets $ 44,946 $ 2,852 $ 5,083 $ 14,235 $ 4,372 $ 71,488 Loans 43,472 2,104 4,935 — — 50,511 Deposits 29,047 20,743 3,833 1,673 185 55,481 Statistical data: Return on average assets (b) 2.27 % 0.39 % 2.76 % n/m n/m 1.68 % Efficiency ratio (c) 35.96 84.49 62.45 n/m n/m 51.82 Year Ended December 31, 2018 Earnings summary: Net interest income (expense) $ 1,613 $ 548 $ 181 $ (46 ) $ 56 $ 2,352 Provision for credit losses 6 (1 ) (3 ) — (3 ) (1 ) Noninterest income 547 136 266 27 — 976 Noninterest expenses 847 602 293 (4 ) 56 1,794 Provision (benefit) for income taxes 283 18 36 (14 ) (23 ) (a) 300 Net income (loss) $ 1,024 $ 65 $ 121 $ (1 ) $ 26 $ 1,235 Net credit-related charge-offs (recoveries) $ 52 $ — $ (1 ) $ — $ — $ 51 Selected average balances: Assets $ 43,207 $ 2,633 $ 5,214 $ 13,705 $ 5,965 $ 70,724 Loans 41,618 2,067 5,081 — — 48,766 Deposits 30,116 20,812 3,941 941 125 55,935 Statistical data: Return on average assets (b) 2.37 % 0.31 % 2.32 % n/m n/m 1.75 % Efficiency ratio (c) 39.22 87.59 65.60 n/m n/m 53.56 (Table continues on following page) (dollar amounts in millions) Business Bank Retail Bank Wealth Management Finance Other Total Year Ended December 31, 2017 Earnings summary: Net interest income (expense) $ 1,513 $ 453 $ 169 $ (111 ) $ 37 $ 2,061 Provision for credit losses 69 2 1 — 2 74 Noninterest income 639 154 255 49 10 1,107 Noninterest expenses 918 615 285 (4 ) 46 1,860 Provision (benefit) for income taxes 410 (4 ) 51 (35 ) 69 (a) 491 Net income (loss) $ 755 $ (6 ) $ 87 $ (23 ) $ (70 ) $ 743 Net credit-related charge-offs (recoveries) $ 96 $ 1 $ (5 ) $ — $ — $ 92 Selected average balances: Assets $ 42,653 $ 2,626 $ 5,401 $ 13,954 $ 6,818 $ 71,452 Loans 41,241 2,061 5,256 — — 48,558 Deposits 31,999 20,775 4,081 241 162 57,258 Statistical data: Return on average assets (b) 1.77 % (0.03 )% 1.61 % n/m n/m 1.04 % Efficiency ratio (c) 42.67 101.29 67.06 n/m n/m 58.70 (a) Primarily reflected discrete tax items, including benefits of $17 million and $48 million in 2019 and 2018 , respectively, and a net charge of $72 million in 2017 . (b) Return on average assets is calculated based on the greater of average assets or average liabilities and attributed equity. (c) 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.
Market Segment Financial Results	Market segment financial results are as follows: (dollar amounts in millions) Michigan California Texas Other Markets Finance & Other Total Year Ended December 31, 2019 Earnings summary: Net interest income (expense) $ 729 $ 811 $ 493 $ 373 $ (67 ) $ 2,339 Provision for credit losses (11 ) (33 ) 119 (5 ) 4 74 Noninterest income 291 173 128 365 53 1,010 Noninterest expenses 554 406 345 369 69 1,743 Provision (benefit) for income taxes 108 155 38 74 (41 ) (a) 334 Net income (loss) $ 369 $ 456 $ 119 $ 300 $ (46 ) $ 1,198 Net credit-related charge-offs (recoveries) $ 11 $ 8 $ 93 $ (5 ) $ — $ 107 Selected average balances: Assets $ 13,157 $ 18,856 $ 11,269 $ 9,599 $ 18,607 $ 71,488 Loans 12,553 18,540 10,616 8,802 — 50,511 Deposits 20,081 16,857 8,780 7,905 1,858 55,481 Statistical data: Return on average assets (b) 1.77 % 2.42 % 1.06 % 3.13 % n/m 1.68 % Efficiency ratio (c) 54.02 41.21 55.59 50.03 n/m 51.82 (Table continues on following page) (dollar amounts in millions) Michigan California Texas Other Markets Finance & Other Total Year Ended December 31, 2018 Earnings summary: Net interest income $ 727 $ 788 $ 474 $ 353 $ 10 $ 2,352 Provision for credit losses 30 26 (53 ) (1 ) (3 ) (1 ) Noninterest income 296 164 130 359 27 976 Noninterest expenses 577 424 365 376 52 1,794 Provision (benefit) for income taxes 90 123 64 60 (37 ) (a) 300 Net income $ 326 $ 379 $ 228 $ 277 $ 25 $ 1,235 Net credit-related charge-offs $ 7 $ 27 $ 12 $ 5 $ — $ 51 Selected average balances: Assets $ 13,207 $ 18,544 $ 10,380 $ 8,922 $ 19,671 $ 70,724 Loans 12,531 18,283 9,812 8,140 — 48,766 Deposits 20,770 16,964 8,992 8,144 1,065 55,935 Statistical data: Return on average assets (b) 1.51 % 2.04 % 2.20 % 3.11 % n/m 1.75 % Efficiency ratio (c) 56.22 44.58 60.30 52.93 n/m 53.56 Year Ended December 31, 2017 Earnings summary: Net interest income (expense) $ 657 $ 711 $ 451 $ 316 $ (74 ) $ 2,061 Provision for credit losses 8 101 (72 ) 36 1 74 Noninterest income 324 171 131 423 58 1,107 Noninterest expenses 589 404 375 450 42 1,860 Provision for income taxes 137 145 104 71 34 (a) 491 Net income (loss) $ 247 $ 232 $ 175 $ 182 $ (93 ) $ 743 Net credit-related (recoveries) charge-offs $ (1 ) $ 33 $ 46 $ 14 $ — $ 92 Selected average balances: Assets $ 13,393 $ 18,269 $ 10,434 $ 8,584 $ 20,772 $ 71,452 Loans 12,676 18,008 9,960 7,914 — 48,558 Deposits 21,818 17,533 9,623 7,881 403 57,258 Statistical data: Return on average assets (b) 1.09 % 1.25 % 1.61 % 2.12 % n/m 1.04 % Efficiency ratio (c) 60.01 45.83 64.35 60.98 n/m 58.70 (a) Primarily reflected discrete tax items, including benefits of $17 million and $48 million in 2019 and 2018 , respectively, and a net charge of $72 million in 2017 . (b) Return on average assets is calculated based on the greater of average assets or average liabilities and attributed equity. (c) 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

Parent Company FInancial Stat_2

Parent Company FInancial Statements Parent Company Financial Statements (Tables)	12 Months Ended
	Dec. 31, 2019
Condensed Financial Information Disclosure [Abstract]
Balance Sheets - Comerica Incorporated	BALANCE SHEETS - COMERICA INCORPORATED (in millions, except share data) December 31 2019 2018 Assets Cash and due from subsidiary bank $ 1,196 $ 1,524 Other short-term investments 95 88 Investment in subsidiaries, principally banks 7,784 7,429 Premises and equipment 1 1 Other assets 242 169 Total assets $ 9,318 $ 9,211 Liabilities and Shareholders’ Equity Medium- and long-term debt $ 1,735 $ 1,459 Other liabilities 256 245 Total liabilities 1,991 1,704 Common stock - $5 par value: Authorized - 325,000,000 shares Issued - 228,164,824 shares 1,141 1,141 Capital surplus 2,174 2,148 Accumulated other comprehensive loss (235 ) (609 ) Retained earnings 9,538 8,781 Less cost of common stock in treasury - 86,069,234 shares at 12/31/19 and 68,081,176 shares at 12/31/18 (5,291 ) (3,954 ) Total shareholders’ equity 7,327 7,507 Total liabilities and shareholders’ equity $ 9,318 $ 9,211
Statements of Income - Comerica Incorporated	STATEMENTS OF INCOME - COMERICA INCORPORATED (in millions) Years Ended December 31 2019 2018 2017 Income Income from subsidiaries: Dividends from subsidiaries $ 1,229 $ 1,135 $ 915 Other interest income 20 13 3 Intercompany management fees 224 228 136 Other noninterest income — — 8 Total income 1,473 1,376 1,062 Expenses Interest on medium- and long-term debt 56 29 13 Salaries and benefits expense 143 140 127 Occupancy expense 6 5 5 Equipment expense 1 1 1 Restructuring charges — 2 6 Other noninterest expenses 72 75 80 Total expenses 278 252 232 Income before benefit for income taxes and equity in undistributed earnings of subsidiaries 1,195 1,124 830 Benefit for income taxes (9 ) (5 ) (26 ) Income before equity in undistributed earnings of subsidiaries 1,204 1,129 856 Equity in undistributed earnings of subsidiaries, principally banks (6 ) 106 (113 ) Net income 1,198 1,235 743 Less income allocated to participating securities 7 8 5 Net income attributable to common shares $ 1,191 $ 1,227 $ 738
Statements of Cash Flows - Comerica Incorporated	STATEMENTS OF CASH FLOWS - COMERICA INCORPORATED (in millions) Years Ended December 31 2019 2018 2017 Operating Activities Net income $ 1,198 $ 1,235 $ 743 Adjustments to reconcile net income to net cash provided by operating activities: Undistributed earnings of subsidiaries, principally banks 6 (106 ) 113 Depreciation and amortization 1 1 1 Net periodic defined benefit cost (credit) 4 4 (2 ) Share-based compensation expense 15 21 16 Benefit for deferred income taxes (2 ) (1 ) (10 ) Other, net 28 10 59 Net cash provided by operating activities 1,250 1,164 920 Financing Activities Medium- and long-term debt: Maturities (350 ) — — Issuances 550 850 — Common Stock: Repurchases (1,394 ) (1,338 ) (560 ) Cash dividends paid (402 ) (263 ) (180 ) Issuances of common stock under employee stock plans 18 52 118 Net cash used in financing activities (1,578 ) (699 ) (622 ) Net (decrease) increase in cash and cash equivalents (328 ) 465 298 Cash and cash equivalents at beginning of period 1,524 1,059 761 Cash and cash equivalents at end of period $ 1,196 $ 1,524 $ 1,059 Interest paid $ 55 $ 11 $ 12 Income taxes recovered $ (226 ) $ (155 ) $ (331 )

Summary of Quarterly Financia_2

Summary of Quarterly Financial Statements (Unaudited) Summary of Quarterly Financial Statements (Unaudited ) (Tables)	12 Months Ended
	Dec. 31, 2019
Quarterly Financial Information Disclosure [Abstract]
Summary of Quarterly Financial Statements	The following quarterly information is unaudited. However, in the opinion of management, the information reflects all adjustments, which are necessary for the fair presentation of the results of operations, for the periods presented. 2019 (in millions, except per share data) Fourth Quarter Third Quarter Second Quarter First Quarter Interest income $ 659 $ 711 $ 727 $ 710 Interest expense 115 125 124 104 Net interest income 544 586 603 606 Provision for credit losses 8 35 44 (13 ) Net securities gains (losses) 1 — — (8 ) Noninterest income excluding net securities gains (losses) 265 256 250 246 Noninterest expenses 451 435 424 433 Provision for income taxes 82 80 87 85 Net income 269 292 298 339 Less income allocated to participating securities 2 2 1 2 Net income attributable to common shares $ 267 $ 290 $ 297 $ 337 Earnings per common share: Basic $ 1.87 $ 1.98 $ 1.95 $ 2.14 Diluted 1.85 1.96 1.94 2.11 Comprehensive income 370 338 429 435 2018 (in millions, except per share data) Fourth Quarter Third Quarter Second Quarter First Quarter Interest income $ 704 $ 675 $ 650 $ 590 Interest expense 90 76 60 41 Net interest income 614 599 590 549 Provision for credit losses 16 — (29 ) 12 Net securities (losses) gains — (20 ) — 1 Noninterest income excluding net securities (losses) gains 250 254 248 243 Noninterest expenses 448 452 448 446 Provision for income taxes 90 63 93 54 Net income 310 318 326 281 Less income allocated to participating securities 2 2 2 2 Net income attributable to common shares $ 308 $ 316 $ 324 $ 279 Earnings per common share: Basic $ 1.91 $ 1.89 $ 1.90 $ 1.62 Diluted 1.88 1.86 1.87 1.59 Comprehensive income 312 296 290 178

Revenue from Contracts with C_2

Revenue from Contracts with Customers Revenue from Contracts wtih Customers (Tables)	12 Months Ended
	Dec. 31, 2019
Revenue from Contracts with Customers [Abstract]
Composition of 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. Business Bank Retail Bank Wealth Management Finance & Other Total (in millions) Year Ended December 31, 2019 Revenue from contracts with customers: Card fees $ 213 $ 40 $ 4 $ — $ 257 Fiduciary income — — 206 — 206 Service charges on deposit accounts 130 68 5 — 203 Commercial loan servicing fees (a) 18 — — — 18 Brokerage fees — — 28 — 28 Other noninterest income (b) 8 11 18 — 37 Total revenue from contracts with customers 369 119 261 — 749 Other sources of noninterest income 186 13 9 53 261 Total noninterest income $ 555 $ 132 $ 270 $ 53 $ 1,010 Year Ended December 31, 2018 Revenue from contracts with customers: Card fees (c) $ 201 $ 39 $ 4 $ — $ 244 Fiduciary income — — 206 — 206 Service charges on deposit accounts (c) 134 72 5 — 211 Commercial loan servicing fees (a) 18 — — — 18 Brokerage fees — — 27 — 27 Other noninterest income (b) 12 19 17 1 49 Total revenue from contracts with customers 365 130 259 1 755 Other sources of noninterest income 182 6 7 26 221 Total noninterest income $ 547 $ 136 $ 266 $ 27 $ 976 Year Ended December 31, 2017 Card fees $ 285 $ 43 $ 5 $ — $ 333 Fiduciary income — — 198 — 198 Services charges on deposit accounts 143 79 5 — 227 Commercial lending fees 84 — 1 — 85 Letter of credit fees 44 — 1 — 45 Bank-owned life insurance — — — 43 43 Foreign exchange income 43 — 2 — 45 Brokerage fees — — 23 — 23 Other noninterest income 40 32 20 16 108 Total noninterest income $ 639 $ 154 $ 255 $ 59 $ 1,107 (a) Included in commercial lending fees on the Consolidated Statements of Income. (b) Excludes derivative, warrant and other miscellaneous income. (c) Adoption of Topic 606 resulted in a change in presentation which records certain costs in the same category as the associated revenues. The effect of this change was to reduce card fees by $140 million and service charges on deposit accounts by $5 million for the twelve months ended December 31, 2018. Refer to Note 1 for further information.

Leases (Tables)

Leases (Tables)	12 Months Ended
	Dec. 31, 2019
Leases [Abstract]
Contractual maturities of sales-type and direct financing lease receivables	As of December 31, 2019 , the contractual maturities of operating lease liabilities were as follows: (in millions) Years Ending December 31 2020 $ 60 2021 62 2022 53 2023 46 2024 42 Thereafter 175 Total contractual maturities 438 Less imputed interest (71 ) Total operating lease liabilities $ 367
Contractual maturities of operating lease liabilities	As of December 31, 2019 , the contractual maturities of sales-type and direct financing lease receivables were as follows: (in millions) Years Ending December 31 2020 $ 66 2021 54 2022 90 2023 45 2024 40 Thereafter 31 Total lease payments receivable 326 Unguaranteed residual values 64 Less deferred interest income (21 ) Total lease receivables (a) $ 369 (a) Excludes net investment in leveraged leases of $219 million .

Basis of Presentation and Acc_3

Basis of Presentation and Accounting Policies Basis of Presentation and Accounting Policies (Narrative) (Details) $ in Millions		12 Months Ended
		Dec. 31, 2019USD ($)markets	Jan. 01, 2020USD ($)	Jan. 01, 2019USD ($)	Dec. 31, 2018USD ($)
Number of Primary Geographic Markets | markets		3
Commitments to fund additional investments in nonmarketable equity securities		$ 1
Federal Home Loan Bank Stock		163			$ 163
Federal Reserve Bank Stock		85			85
Net Deferred Income on Originated Loans		103			115
Allowance for Credit Losses, Threshold for Individual Evaluation, Nonaccrual Loans		2
Allowance for Credit losses, Threshold for Individual Evaluation, TDR		$ 1
Delinquency Status, Period of Unpaid Scheduled Monthly Payment		30 days
Right of use assets		$ 329
Operating lease liabilities		$ 367
Number of Reporting Units		3
Notional Amount	[1]	$ 30,134			21,557
Defined Benefit Plan Investment Gain Loss Amortization Adjustment, Allowable Percentage		10.00%
Defined Benefit Plan Actuarial Gain Loss Amortization Adjustment, Allowable Percentage		10.00%
Defined Benefit Plan Market-related Value Plan Assets, Amortization Period		5 years
Overall allowance for credit losses		$ 668
Business loans percent of portfolio		91.00%
Premises the Corporation owns | Minimum
Premises and Equipment, Useful Life		3 years
Premises the Corporation owns | Maximum
Premises and Equipment, Useful Life		33 years
Furniture and equipment | Minimum
Premises and Equipment, Useful Life		3 years
Furniture and equipment | Maximum
Premises and Equipment, Useful Life		8 years
Leasehold improvements | Maximum
Premises and Equipment, Useful Life		10 years
Software
Premises and Equipment, Useful Life		5 years
Carrying Amount
Nonmarketable equity securities	[2]	$ 5			$ 6
Retail loans | Real estate mortgage
Past Due Period Residential Mortgage And Home Equity Loans Placed On Nonaccrual Status		90 days
Past Due Threshold For Charge-Off		180 days
Commercial borrower | Business loans
Past Due Period Business Loans Placed On Nonaccrual Status		90 days
Consumer borrower | Retail loans | Home equity
Maximum Past Due Status Junior Lien Home Equity Placed On Nonaccrual Status		90 days
Consumer borrower | Retail loans | Other consumer
Past Due Threshold For Charge-Off		120 days
Threshold, Days Past Due, Other Consumer Placed On Nonaccrual Status		90 days
Accounting Standards Update 2016-02 [Member]
Right of use assets				$ 329
Operating lease liabilities				343
Accounting Standards Update 2016-13 [Member]
Day-one decrease in the overall allowance for credit losses			$ 17
Reduction to deferred tax asset			$ 4
Increase in CET1			0.02%
Reduction in business loans allowance for credit losses			$ 42
Increase in retail loans allowance for credit losses			25
Retained Earnings | Accounting Standards Update 2016-02 [Member]
Cumulative effect of change in accounting principle				$ 14
Retained Earnings | Accounting Standards Update 2016-13 [Member]
Cumulative effect of change in accounting principle			$ 13
Fair Value Hedging | Short-Cut Method | Designated as Hedging Instrument | Interest rate swap
Notional Amount		$ 2,100
[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 on the Consolidated Balance Sheets.
[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.

Fair Value Measurements (Narrat

Fair Value Measurements (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Recurring
Transfers into or out of Level 1 or Level 2 or Level 3	$ 0	$ 0
Total liabilities at fair value	236	357
Nonrecurring
Total liabilities at fair value	$ 0	$ 0

Fair Value Measurements (Assets

Fair Value Measurements (Assets And Liabilities Recorded At Fair Value On A Recurring Basis) (Details) - USD ($) $ in Millions		Dec. 31, 2019	Dec. 31, 2018
Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Investment securities available-for-sale		$ 12,398	$ 12,045
Derivative assets		317	275
Derivative Liability	[1]	66	223
Derivative liabilities		141	269
U.S. Treasury and other U.S. government agency securities
Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Investment securities available-for-sale		2,792	2,727
Residential mortgage-backed securities
Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Investment securities available-for-sale	[2]	9,606	9,318
Recurring
Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Investment securities available-for-sale		12,398	12,045
Derivative assets		317	275
Total assets at fair value		12,864	12,451
Derivative liabilities		141	269
Deferred compensation plan liabilities		95	88
Total liabilities at fair value		236	357
Recurring | Level 1
Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Investment securities available-for-sale		2,792	2,727
Derivative assets		0	0
Total assets at fair value		2,941	2,858
Derivative Liability		0	0
Deferred compensation plan liabilities		95	88
Total liabilities at fair value		95	88
Recurring | Level 2
Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Investment securities available-for-sale		9,606	9,318
Derivative assets		295	266
Total assets at fair value		9,901	9,584
Derivative Liability		141	269
Deferred compensation plan liabilities		0	0
Total liabilities at fair value		141	269
Recurring | Level 3
Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Investment securities available-for-sale		0	0
Derivative assets		22	9
Total assets at fair value		22	9
Derivative Liability		0	0
Deferred compensation plan liabilities		0	0
Total liabilities at fair value		0	0
Recurring | Interest rate contracts
Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Derivative assets		211	67
Derivative Liability		39	70
Recurring | Interest rate contracts | Level 1
Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Derivative assets			0
Derivative Liability		0	0
Recurring | Interest rate contracts | Level 2
Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Derivative assets		189	58
Derivative Liability		39	70
Recurring | Interest rate contracts | Level 3
Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Derivative assets		22	9
Derivative Liability		0	0
Recurring | Energy derivative contracts
Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Derivative assets		96	189
Derivative Liability		92	186
Recurring | Energy derivative contracts | Level 1
Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Derivative assets		0	0
Derivative Liability		0	0
Recurring | Energy derivative contracts | Level 2
Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Derivative assets		96	189
Derivative Liability		92	186
Recurring | Energy derivative contracts | Level 3
Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Derivative assets		0	0
Derivative Liability		0	0
Recurring | Foreign exchange contracts
Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Derivative assets		10	19
Derivative Liability		10	13
Recurring | Foreign exchange contracts | Level 1
Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Derivative assets		0	0
Derivative Liability		0	0
Recurring | Foreign exchange contracts | Level 2
Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Derivative assets		10	19
Derivative Liability		10	13
Recurring | Foreign exchange contracts | Level 3
Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Derivative assets		0	0
Derivative Liability		0	0
Recurring | Deferred compensation plan assets
Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Other equity securities		95	88
Recurring | Deferred compensation plan assets | Level 1
Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Other equity securities		95	88
Recurring | Deferred compensation plan assets | Level 2
Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Other equity securities		0	0
Recurring | Deferred compensation plan assets | Level 3
Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Other equity securities		0	0
Recurring | Equity and other non-debt securities
Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Other equity securities		54
Recurring | Equity and other non-debt securities | Level 1
Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Other equity securities		54
Recurring | Equity and other non-debt securities | Level 2
Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Other equity securities		0
Recurring | Equity and other non-debt securities | Level 3
Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Other equity securities		0
Recurring | U.S. Treasury and other U.S. government agency securities
Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Investment securities available-for-sale		2,792	2,727
Recurring | U.S. Treasury and other U.S. government agency securities | Level 1
Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Investment securities available-for-sale		2,792	2,727
Recurring | U.S. Treasury and other U.S. government agency securities | Level 2
Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Investment securities available-for-sale		0	0
Recurring | U.S. Treasury and other U.S. government agency securities | Level 3
Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Investment securities available-for-sale		0	0
Recurring | Residential mortgage-backed securities
Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Other equity securities			43
Investment securities available-for-sale	[2]	9,606	9,318
Recurring | Residential mortgage-backed securities | Level 1
Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Other equity securities			43
Investment securities available-for-sale	[2]	0	0
Recurring | Residential mortgage-backed securities | Level 2
Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Other equity securities			0
Investment securities available-for-sale	[2]	9,606	9,318
Recurring | Residential mortgage-backed securities | Level 3
Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Other equity securities			0
Investment securities available-for-sale	[2]	$ 0	$ 0
[1]	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 $9 million and $2 million at December 31, 2019 and 2018 , respectively.
[2]	Issued and/or guaranteed by U.S. government agencies or U.S. government-sponsored enterprises.

Fair Value Measurements (Change

Fair Value Measurements (Changes In Level 3 Assets And Liabilities Measured At Fair Value On A Recurring Basis) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2019		Dec. 31, 2018	Jan. 01, 2018
Interest rate contracts
Balance at beginning of period		$ 9		$ 14
Realized gains (losses) recorded in earnings		1	[1]	0
Unrealized gains (losses) recorded in earnings	[1]	13		(5)
Sales and redemptions		(1)		0
Balance at end of period		22		9
Investment securities available-for-sale
Balance at beginning of period		0		49
Change in classification	[2]				$ (44)
Realized gains (losses) recorded in earnings				0
Unrealized gains (losses) recorded in earnings				0
Sales and redemptions				(5)
Balance at end of period				0
Equity and other non-debt securities | Equity and other non-debt securities
Change in classification	[2]				44
Sales and redemptions				(44)
Equity and other non-debt securities | Investment securities available-for-sale
Balance at beginning of period	[2]	0		44
Change in classification	[2]				$ (44)
Realized gains (losses) recorded in earnings	[2]			0
Unrealized gains (losses) recorded in earnings	[2]			0
Sales and redemptions	[2]			0
Balance at end of period	[2]			0
State and municipal securities | Investment securities available-for-sale
Balance at beginning of period	[2]	$ 0		5
Realized gains (losses) recorded in earnings	[2]			0
Unrealized gains (losses) recorded in earnings	[2]			0
Sales and redemptions	[2]			(5)
Balance at end of period	[2]			$ 0
[1]	Realized and unrealized gains and losses due to changes in fair value recorded in other noninterest income on the Consolidated Statements of Income.
[2]	Auction-rate securities.

Fair Value Measurements (Asse_2

Fair Value Measurements (Assets And Liabilities Recorded At Fair Value On A Nonrecurring Basis) (Details) - Nonrecurring - Level 3 - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Assets and Liabilities Measured at Fair Value on a Nonrecurring Basis [Line Items]
Loans		$ 100
Total assets at fair value	$ 70	108
Commercial borrower | Domestic loans
Assets and Liabilities Measured at Fair Value on a Nonrecurring Basis [Line Items]
Loans	$ 70	96
Commercial borrower | Commercial mortgage loans | Domestic loans
Assets and Liabilities Measured at Fair Value on a Nonrecurring Basis [Line Items]
Loans		4
Residential mortgage | Domestic loans
Assets and Liabilities Measured at Fair Value on a Nonrecurring Basis [Line Items]
Loans		$ 8

Fair Value Measurements (Estima

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		Dec. 31, 2019	Dec. 31, 2018
Cash and due from banks		$ 973	$ 1,390
Interest-bearing deposits with banks		4,845	3,171
Total loans, net of allowance for loan losses		49,732	49,492
Demand deposits (noninterest-bearing)		27,382	28,690
Customer certificates of deposit		2,978	2,131
Other time deposits		133	0
Total deposits		57,295	55,561
Short-term borrowings		71	44
Medium- and long-term debt		7,269	6,463
Carrying Amount
Cash and due from banks		973	1,390
Interest-bearing deposits with banks		4,845	3,171
Loans held-for-sale		6	3
Total loans, net of allowance for loan losses	[1]	49,732	49,492
Customers' liability on acceptances outstanding		2	4
Restricted equity investments		248	248
Nonmarketable equity securities	[2]	5	6
Demand deposits (noninterest-bearing)		27,382	28,690
Interest-bearing deposits		26,802	24,740
Customer certificates of deposit		2,978	2,131
Other time deposits		133
Total deposits		57,295	55,561
Short-term borrowings		71	44
Acceptances outstanding		2	4
Medium- and long-term debt		7,269	6,463
Credit-related financial instruments		(57)	(57)
Estimated Fair Value
Cash and due from banks		973	1,390
Interest-bearing deposits with banks		4,845	3,171
Loans held-for-sale		6	3
Total loans, net of allowance for loan losses	[1]	49,975	48,889
Customers' liability on acceptances outstanding		2	4
Restricted equity investments		248	248
Nonmarketable equity securities	[2]	10	11
Demand deposits (noninterest-bearing)		27,382	28,690
Interest-bearing deposits		26,802	24,740
Customer certificates of deposit		2,968	2,100
Other time deposits		133
Total deposits		57,285	55,530
Short-term borrowings		71	44
Acceptances outstanding		2	4
Medium- and long-term debt		7,316	6,436
Credit-related financial instruments		(57)	(57)
Level 1 | Estimated Fair Value
Cash and due from banks		973	1,390
Interest-bearing deposits with banks		4,845	3,171
Loans held-for-sale		0	0
Total loans, net of allowance for loan losses	[1]	0	0
Customers' liability on acceptances outstanding		2	4
Restricted equity investments		248	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		71	44
Acceptances outstanding		2	4
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		6	3
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)		27,382	28,690
Interest-bearing deposits		26,802	24,740
Customer certificates of deposit		2,968	2,100
Other time deposits		133
Total deposits		57,285	55,530
Short-term borrowings		0	0
Acceptances outstanding		0	0
Medium- and long-term debt		7,316	6,436
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]	49,975	48,889
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		(57)	(57)
Nonrecurring
Total loans, net of allowance for loan losses		$ 70	$ 108
[1]	Included $70 million and $108 million of impaired loans recorded at fair value on a nonrecurring basis at December 31, 2019 and 2018 , 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.

Investment Securities (Narrativ

Investment Securities (Narrative) (Details) $ in Millions		3 Months Ended								12 Months Ended
		Dec. 31, 2019USD ($)	Sep. 30, 2019USD ($)	Jun. 30, 2019USD ($)	Mar. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Sep. 30, 2018USD ($)	Mar. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)
Securities with no credit impairment in unrealized loss position		170								170
Repositioning lower-yielding treasury securities										$ 1,000	$ 1,300
Net securities losses		$ 1	$ 0	$ 0	$ (8)	$ 0	$ (20)	$ 1	$ 0	(7)	(19)	$ 0
Investment securities available-for-sale, Amortized Cost		12,313				12,225				12,313	12,225
Carrying value of securities pledged		518								518
Liabilities secured by pledged collateral		418								418
U.S. Treasury and other U.S. government agency securities
Investment securities available-for-sale, Amortized Cost		2,745				2,732				2,745	2,732
Residential mortgage-backed securities
Investment securities available-for-sale, Amortized Cost	[1]	9,568				$ 9,493				9,568	$ 9,493
Debt securities
Investment securities available-for-sale, Amortized Cost		12,313								12,313
Prepayment options | Residential mortgage-backed securities
Investment securities available-for-sale, Amortized Cost		$ 9,600								$ 9,600
[1]	Issued and/or guaranteed by U.S. government agencies or U.S. government-sponsored enterprises.

Investment Securities (Summary

Investment Securities (Summary Of Investment Securities) (Details) - USD ($) $ in Millions		Dec. 31, 2019	Dec. 31, 2018
Investment securities available-for-sale, Amortized Cost		$ 12,313	$ 12,225
Investment securities available-for-sale, Gross Unrealized Gains		113	36
Investment securities available-for-sale, Gross Unrealized Losses		28	216
Investment securities available-for-sale, Fair Value		12,398	12,045
U.S. Treasury and other U.S. government agency securities
Investment securities available-for-sale, Amortized Cost		2,745	2,732
Investment securities available-for-sale, Gross Unrealized Gains		47	14
Investment securities available-for-sale, Gross Unrealized Losses		0	19
Investment securities available-for-sale, Fair Value		2,792	2,727
Residential mortgage-backed securities
Investment securities available-for-sale, Amortized Cost	[1]	9,568	9,493
Investment securities available-for-sale, Gross Unrealized Gains	[1]	66	22
Investment securities available-for-sale, Gross Unrealized Losses	[1]	28	197
Investment securities available-for-sale, Fair Value	[1]	$ 9,606	$ 9,318
[1]	Issued and/or guaranteed by U.S. government agencies or U.S. government-sponsored enterprises.

Investment Securities (Summar_2

Investment Securities (Summary Of Investment Securities In Unrealized Loss Positions) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018
Document Period End Date		Dec. 31, 2019
Temporarily Impaired Less than 12 Months, Fair Value		$ 1,494	$ 1,008
Temporarily Impaired, Less than 12 Months, Unrealized Losses		7	9
Temporarily Impaired 12 Months or more, Fair Value		1,906	7,869
Temporarily Impaired, 12 Months or more, Unrealized Losses		21	207
Temporarily Impaired Total, Fair Value		3,400	8,877
Temporarily Impaired Total, Unrealized Losses		28	216
U.S. Treasury and other U.S. government agency securities
Temporarily Impaired Less than 12 Months, Fair Value			0
Temporarily Impaired, Less than 12 Months, Unrealized Losses			0
Temporarily Impaired 12 Months or more, Fair Value			1,457
Temporarily Impaired, 12 Months or more, Unrealized Losses			19
Temporarily Impaired Total, Fair Value			1,457
Temporarily Impaired Total, Unrealized Losses			19
Residential mortgage-backed securities
Temporarily Impaired Less than 12 Months, Fair Value	[1]	1,494	1,008
Temporarily Impaired, Less than 12 Months, Unrealized Losses	[1]	7	9
Temporarily Impaired 12 Months or more, Fair Value	[1]	1,906	6,412
Temporarily Impaired, 12 Months or more, Unrealized Losses	[1]	21	188
Temporarily Impaired Total, Fair Value	[1]	3,400	7,420
Temporarily Impaired Total, Unrealized Losses	[1]	$ 28	$ 197
[1]	Issued and/or guaranteed by U.S. government agencies or U.S. government-sponsored enterprises.

Investment Securities (Gains An

Investment Securities (Gains And Losses On Securities) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Investments, Debt and Equity Securities [Abstract]
Securities gains									$ 1	$ 2
Securities losses									(8)	(21)
Net securities losses	$ 1	$ 0	$ 0	$ (8)	$ 0	$ (20)	$ 1	$ 0	$ (7)	$ (19)	$ 0

Investment Securities (Contract

Investment Securities (Contractual Maturity Distribution Of Debt Securities) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Document Period End Date	Dec. 31, 2019
Investment securities available-for-sale, Amortized Cost	$ 12,313	$ 12,225
Investment securities available-for-sale, Fair Value	12,398	$ 12,045
Debt securities
Available-for-sale, Within one year, Amortized Cost	30
Available-for-sale, After one year through five years, Amortized Cost	2,842
Available-for-sale, After five years through ten years, Amortized Cost	1,006
Available-for-sale, After ten years, Amortized Cost	8,435
Available-for-sale, Within one year, Fair Value	30
Available-for-sale, After one year through five years, Fair Value	2,894
Available-for-sale, After five years through ten years, Fair Value	1,013
Available-for-sale, After ten years, Fair Value	8,461
Investment securities available-for-sale, Amortized Cost	12,313
Investment securities available-for-sale, Fair Value	$ 12,398

Credit Quality And Allowance _3

Credit Quality And Allowance For Credit Losses (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Retail loans secured by residential real estate in process of foreclosure	$ 0	$ 1
Commitments to lend additional funds to TDR borrowers	3	20
Principal deferrals
Subsequent default during period	$ 12	$ 0
AB Note Restructures
Days past due defined as subsequent default	90 days	90 days
Subsequent default during period	$ 0	$ 0
Interest Rate Reductions
Days past due defined as subsequent default	90 days	90 days
Subsequent default during period	$ 0	$ 0

Credit Quality And Allowance _4

Credit Quality And Allowance For Credit Losses (Aging Analysis Of Loans) (Details) - USD ($) $ in Millions		Dec. 31, 2019	Dec. 31, 2018
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		$ 153	$ 149
Nonaccrual loans		199	221
Current loans		50,017	49,793
Total loans		50,369	50,163
30 to 59 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		80	98
60 to 89 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		47	35
90 days or more past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		26	16
Real estate construction
Financing Receivable, Past Due [Line Items]
Total loans		3,455	3,077
Real estate mortgage
Financing Receivable, Past Due [Line Items]
Total loans		9,559	9,106
Business loans | Commercial borrower
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		122	129
Nonaccrual loans		162	166
Current loans		45,800	45,384
Total loans		46,084	45,679
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		59	82
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		37	31
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		26	16
Business loans | Commercial borrower | Domestic loans
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		51	68
Nonaccrual loans		148	141
Current loans		31,274	31,767
Total loans		31,473	31,976
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		27	34
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		7	26
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		17	8
Business loans | Commercial borrower | International loans
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		5	0
Nonaccrual loans		0	3
Current loans		1,004	1,010
Total loans		1,009	1,013
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		5	0
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		0	0
Business loans | Commercial borrower | Real estate construction | Domestic loans
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		13	12
Nonaccrual loans		0	0
Current loans		3,442	3,065
Total loans		3,455	3,077
Business loans | Commercial borrower | Real estate construction | Domestic loans | 30 to 59 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		6	12
Business loans | Commercial borrower | Real estate construction | Domestic loans | 60 to 89 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		7	0
Business loans | Commercial borrower | Real estate construction | 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 | Commercial borrower | Real estate construction | Domestic loans | Commercial Real Estate business line
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing	[1]	6	6
Nonaccrual loans	[1]	0	0
Current loans	[1]	3,038	2,681
Total loans	[1]	3,044	2,687
Business loans | Commercial borrower | Real estate construction | 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	[1]	6	6
Business loans | Commercial borrower | Real estate construction | 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	[1]	0	0
Business loans | Commercial borrower | Real estate construction | 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	[1]	0	0
Business loans | Commercial borrower | Real estate construction | Domestic loans | Other business lines
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing	[2]	7	6
Nonaccrual loans	[2]	0	0
Current loans	[2]	404	384
Total loans	[2]	411	390
Business loans | Commercial borrower | Real estate construction | 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	[2]	0	6
Business loans | Commercial borrower | Real estate construction | 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	[2]	7	0
Business loans | Commercial borrower | Real estate construction | 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	[2]	0	0
Business loans | Commercial borrower | Real estate mortgage | Domestic loans
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		52	49
Nonaccrual loans		14	20
Current loans		9,493	9,037
Total loans		9,559	9,106
Business loans | Commercial borrower | Real estate mortgage | Domestic loans | 30 to 59 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		25	36
Business loans | Commercial borrower | Real estate mortgage | Domestic loans | 60 to 89 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		18	5
Business loans | Commercial borrower | Real estate mortgage | Domestic loans | 90 days or more past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		9	8
Business loans | Commercial borrower | Real estate mortgage | Domestic loans | Commercial Real Estate business line
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing	[1]	9	4
Nonaccrual loans	[1]	2	2
Current loans	[1]	2,165	1,737
Total loans	[1]	2,176	1,743
Business loans | Commercial borrower | Real estate mortgage | 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	[1]	9	4
Business loans | Commercial borrower | Real estate mortgage | 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	[1]	0	0
Business loans | Commercial borrower | Real estate mortgage | 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	[1]	0	0
Business loans | Commercial borrower | Real estate mortgage | Domestic loans | Other business lines
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing	[2]	43	45
Nonaccrual loans	[2]	12	18
Current loans	[2]	7,328	7,300
Total loans	[2]	7,383	7,363
Business loans | Commercial borrower | Real estate mortgage | 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	[2]	16	32
Business loans | Commercial borrower | Real estate mortgage | 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	[2]	18	5
Business loans | Commercial borrower | Real estate mortgage | 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	[2]	9	8
Business loans | Commercial borrower | Lease financing | Domestic loans
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		1	0
Nonaccrual loans		0	2
Current loans		587	505
Total loans		588	507
Business loans | Commercial borrower | Lease financing | Domestic loans | 30 to 59 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		1	0
Business loans | Commercial borrower | Lease financing | 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 | Commercial borrower | Lease financing | 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		31	20
Nonaccrual loans		37	55
Current loans		4,217	4,409
Total loans		4,285	4,484
Retail loans | 30 to 59 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		21	16
Retail loans | 60 to 89 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		10	4
Retail 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 | Residential mortgage
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		17	14
Nonaccrual loans		20	36
Current loans		1,808	1,920
Total loans		1,845	1,970
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		15	11
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		2	3
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 | Consumer borrower
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		14	6
Nonaccrual loans		17	19
Current loans		2,409	2,489
Total loans		2,440	2,514
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		6	5
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		8	1
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		0	0
Retail loans | Consumer borrower | Home equity
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		9	5
Nonaccrual loans		17	19
Current loans		1,685	1,741
Total loans		1,711	1,765
Retail loans | Consumer borrower | Home equity | 30 to 59 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		4	4
Retail loans | Consumer borrower | Home equity | 60 to 89 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		5	1
Retail loans | Consumer borrower | Home equity | 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 | Consumer borrower | Other consumer
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		5	1
Nonaccrual loans		0	0
Current loans		724	748
Total loans		729	749
Retail loans | Consumer borrower | Other consumer | 30 to 59 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		2	1
Retail loans | Consumer borrower | Other consumer | 60 to 89 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		3	0
Retail loans | Consumer borrower | Other consumer | 90 days or more past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		$ 0	$ 0
[1]	Primarily loans to real estate developers.
[2]	Primarily loans secured by owner-occupied real estate.

Credit Quality And Allowance _5

Credit Quality And Allowance For Credit Losses (Loans By Credit Quality Indicator) (Details) - USD ($) $ in Millions		Dec. 31, 2019	Dec. 31, 2018
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans		$ 50,369	$ 50,163
Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[1]	48,249	48,615
Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[2]	1,064	638
Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[3]	857	689
Nonaccrual
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[4]	199	221
Real estate construction
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans		3,455	3,077
Real estate mortgage
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans		9,559	9,106
Business loans | Commercial borrower
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans		46,084	45,679
Business loans | Commercial borrower | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[1]	44,022	44,198
Business loans | Commercial borrower | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[2]	1,055	634
Business loans | Commercial borrower | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[3]	845	681
Business loans | Commercial borrower | Nonaccrual
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[4]	162	166
Business loans | Commercial borrower | Domestic loans
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans		31,473	31,976
Business loans | Commercial borrower | Domestic loans | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[1]	29,785	30,817
Business loans | Commercial borrower | Domestic loans | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[2]	841	464
Business loans | Commercial borrower | Domestic loans | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[3]	699	554
Business loans | Commercial borrower | Domestic loans | Nonaccrual
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[4]	148	141
Business loans | Commercial borrower | International loans
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans		1,009	1,013
Business loans | Commercial borrower | International loans | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[1]	972	996
Business loans | Commercial borrower | International loans | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[2]	29	4
Business loans | Commercial borrower | International loans | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[3]	8	10
Business loans | Commercial borrower | International loans | Nonaccrual
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[4]	0	3
Business loans | Commercial borrower | Real estate construction | Domestic loans
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans		3,455	3,077
Business loans | Commercial borrower | Real estate construction | Domestic loans | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[1]	3,424	3,046
Business loans | Commercial borrower | Real estate construction | Domestic loans | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[2]	19	31
Business loans | Commercial borrower | Real estate construction | Domestic loans | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[3]	12	0
Business loans | Commercial borrower | Real estate construction | Domestic loans | Nonaccrual
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[4]	0	0
Business loans | Commercial borrower | Real estate construction | Domestic loans | Commercial Real Estate business line
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[5]	3,044	2,687
Business loans | Commercial borrower | Real estate construction | Domestic loans | Commercial Real Estate business line | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[1],[5]	3,013	2,664
Business loans | Commercial borrower | Real estate construction | Domestic loans | Commercial Real Estate business line | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[2],[5]	19	23
Business loans | Commercial borrower | Real estate construction | Domestic loans | Commercial Real Estate business line | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[3],[5]	12	0
Business loans | Commercial borrower | Real estate construction | Domestic loans | Commercial Real Estate business line | Nonaccrual
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[4],[5]	0	0
Business loans | Commercial borrower | Real estate construction | Domestic loans | Other business lines
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[6]	411	390
Business loans | Commercial borrower | Real estate construction | Domestic loans | Other business lines | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[1],[6]	411	382
Business loans | Commercial borrower | Real estate construction | Domestic loans | Other business lines | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[2],[6]	0	8
Business loans | Commercial borrower | Real estate construction | Domestic loans | Other business lines | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[3],[6]	0	0
Business loans | Commercial borrower | Real estate construction | Domestic loans | Other business lines | Nonaccrual
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[4],[6]	0	0
Business loans | Commercial borrower | Real estate mortgage | Domestic loans
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans		9,559	9,106
Business loans | Commercial borrower | Real estate mortgage | Domestic loans | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[1]	9,262	8,839
Business loans | Commercial borrower | Real estate mortgage | Domestic loans | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[2]	159	132
Business loans | Commercial borrower | Real estate mortgage | Domestic loans | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[3]	124	115
Business loans | Commercial borrower | Real estate mortgage | Domestic loans | Nonaccrual
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[4]	14	20
Business loans | Commercial borrower | Real estate mortgage | Domestic loans | Commercial Real Estate business line
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[5]	2,176	1,743
Business loans | Commercial borrower | Real estate mortgage | Domestic loans | Commercial Real Estate business line | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[1],[5]	2,121	1,682
Business loans | Commercial borrower | Real estate mortgage | Domestic loans | Commercial Real Estate business line | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[2],[5]	12	14
Business loans | Commercial borrower | Real estate mortgage | Domestic loans | Commercial Real Estate business line | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[3],[5]	41	45
Business loans | Commercial borrower | Real estate mortgage | Domestic loans | Commercial Real Estate business line | Nonaccrual
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[4],[5]	2	2
Business loans | Commercial borrower | Real estate mortgage | Domestic loans | Other business lines
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[6]	7,383	7,363
Business loans | Commercial borrower | Real estate mortgage | Domestic loans | Other business lines | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[1],[6]	7,141	7,157
Business loans | Commercial borrower | Real estate mortgage | Domestic loans | Other business lines | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[2],[6]	147	118
Business loans | Commercial borrower | Real estate mortgage | Domestic loans | Other business lines | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[3],[6]	83	70
Business loans | Commercial borrower | Real estate mortgage | Domestic loans | Other business lines | Nonaccrual
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[4],[6]	12	18
Business loans | Commercial borrower | Lease financing | Domestic loans
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans		588	507
Business loans | Commercial borrower | Lease financing | Domestic loans | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[1]	579	500
Business loans | Commercial borrower | Lease financing | Domestic loans | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[2]	7	3
Business loans | Commercial borrower | Lease financing | Domestic loans | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[3]	2	2
Business loans | Commercial borrower | Lease financing | Domestic loans | Nonaccrual
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[4]	0	2
Retail loans
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans		4,285	4,484
Retail loans | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[1]	4,227	4,417
Retail loans | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[2]	9	4
Retail loans | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[3]	12	8
Retail loans | Nonaccrual
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[4]	37	55
Retail loans | Residential mortgage
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans		1,845	1,970
Retail loans | Residential mortgage | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[1]	1,823	1,931
Retail loans | Residential mortgage | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[2]	2	3
Retail loans | Residential mortgage | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[3]	0	0
Retail loans | Residential mortgage | Nonaccrual
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[4]	20	36
Retail loans | Consumer borrower
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans		2,440	2,514
Retail loans | Consumer borrower | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[1]	2,404	2,486
Retail loans | Consumer borrower | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[2]	7	1
Retail loans | Consumer borrower | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[3]	12	8
Retail loans | Consumer borrower | Nonaccrual
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[4]	17	19
Retail loans | Consumer borrower | Home equity
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans		1,711	1,765
Retail loans | Consumer borrower | Home equity | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[1]	1,682	1,738
Retail loans | Consumer borrower | Home equity | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[2]	1	0
Retail loans | Consumer borrower | Home equity | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[3]	11	8
Retail loans | Consumer borrower | Home equity | Nonaccrual
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[4]	17	19
Retail loans | Consumer borrower | Other consumer
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans		729	749
Retail loans | Consumer borrower | Other consumer | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[1]	722	748
Retail loans | Consumer borrower | Other consumer | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[2]	6	1
Retail loans | Consumer borrower | Other consumer | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[3]	1	0
Retail loans | Consumer borrower | Other consumer | Nonaccrual
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[4]	$ 0	$ 0
[1]	Includes all loans not included in the categories of special mention, substandard or nonaccrual.
[2]	Special mention loans are accruing loans that 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. This category is generally consistent with the "special mention" category as defined by regulatory authorities.
[3]	Substandard loans are accruing loans that 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 also are distinguished by the distinct possibility of loss in the future if these weaknesses are not corrected. This category is generally consistent with the "substandard" category as defined by regulatory authorities.
[4]	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. A significant majority of nonaccrual loans are generally consistent with the "substandard" category and the remainder are generally consistent with the "doubtful" category as defined by regulatory authorities.
[5]	Primarily loans to real estate developers.
[6]	Primarily loans secured by owner-occupied real estate.

Credit Quality And Allowance _6

Credit Quality And Allowance For Credit Losses (Schedule Of Nonaccrual, Reduced-Rate Loans And Foreclosed Property) (Details) - USD ($) $ in Millions		Dec. 31, 2019	Dec. 31, 2018
Nonaccrual loans		$ 199	$ 221
Reduced-rate loans	[1]	5	8
Total nonperforming loans		204	229
Foreclosed property		11	1
Total nonperforming assets		215	230
Business loans
Reduced-rate loans		0
Retail loans
Nonaccrual loans		37	55
Reduced-rate loans		$ 5	$ 8
[1]	Comprised of reduced-rate retail loans.

Credit Quality And Allowance _7

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								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Financing Receivable, Allowance for Credit Loss [Line Items]
Provision for loan losses	$ 8	$ 35	$ 44	$ (13)	$ 16	$ 0	$ 12	$ (29)	$ 74	$ (1)	$ 74
Total loans												$ 50,369	$ 50,163
Financing Receivable [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Balance at beginning of period				671			712		671	712	730
Loan charge-offs									(152)	(103)	(149)
Recoveries on loans previously charged-off									45	52	57
Net loan (charge-offs) recoveries									(107)	(51)	(92)
Provision for loan losses									73	(11)	(73)
Foreign currency translation adjustment									0	1	(1)
Balance at end of period	637				671			712	637	671	712
As a percentage of total loans												1.27%	1.34%	1.45%
Allowance for loan losses individually evaluated for impairment												$ 31	$ 27	$ 67
Allowance for loan losses collectively evaluated for impairment												606	644	645
Total allowance for loan losses	637			671	671		712	712	671	712	712	637	671	712
Loans individually evaluated for impairment												215	276	477
Loans collectively evaluated for impairment												50,154	49,887	48,696
Total loans												$ 50,369	$ 50,163	$ 49,173
Business loans | Financing Receivable [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Balance at beginning of period				627			661		627	661	682
Loan charge-offs									(147)	(99)	(143)
Recoveries on loans previously charged-off									40	47	50
Net loan (charge-offs) recoveries									(107)	(52)	(93)
Provision for loan losses									81	(19)	(71)
Foreign currency translation adjustment									0	(1)	1
Balance at end of period	601				627			661	601	627	661
As a percentage of total loans												1.30%	1.37%	1.48%
Allowance for loan losses individually evaluated for impairment												$ 31	$ 27	$ 67
Allowance for loan losses collectively evaluated for impairment												570	600	594
Total allowance for loan losses	601			627	627		661	661	601	661	661	601	627	661
Loans individually evaluated for impairment												199	240	443
Loans collectively evaluated for impairment												45,885	45,439	44,188
Total loans												46,084	45,679	$ 44,631
Retail loans
Financing Receivable, Allowance for Credit Loss [Line Items]
Total loans												$ 4,285	$ 4,484
Retail loans | Financing Receivable [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Balance at beginning of period				44			51		44	51	48
Loan charge-offs									(5)	(4)	(6)
Recoveries on loans previously charged-off									5	5	7
Net loan (charge-offs) recoveries									0	1	1
Provision for loan losses									(8)	8	(2)
Foreign currency translation adjustment									0	0	0
Balance at end of period	36				44			51	36	44	51
As a percentage of total loans												0.84%	0.97%	1.12%
Allowance for loan losses individually evaluated for impairment												$ 0	$ 0	$ 0
Allowance for loan losses collectively evaluated for impairment												36	44	51
Total allowance for loan losses	$ 36			$ 44	$ 44		$ 51	$ 51	$ 36	$ 51	$ 51	36	44	51
Loans individually evaluated for impairment												16	36	34
Loans collectively evaluated for impairment												4,269	4,448	4,508
Total loans												$ 4,285	$ 4,484	$ 4,542

Credit Quality And Allowance _8

Credit Quality And Allowance For Credit Losses (Changes In The Allowance For Credit Losses On Lending-Related Commitments) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Financing Receivable, Allowance for Credit Loss [Line Items]
Provision for credit losses on lending-related commitments	$ (8)	$ (35)	$ (44)	$ 13	$ (16)	$ 0	$ (12)	$ 29	$ (74)	$ 1	$ (74)
Lending-related commitments
Financing Receivable, Allowance for Credit Loss [Line Items]
Balance at beginning of period				$ 30			$ 42		30	42	41
Provision for credit losses on lending-related commitments									1	(12)	1
Balance at end of period	$ 31				$ 30			$ 42	$ 31	$ 30	$ 42

Credit Quality And Allowance _9

Credit Quality And Allowance For Credit Losses (Individually Evaluated Impaired Loans) (Details) - USD ($) $ in Millions		Dec. 31, 2019	Dec. 31, 2018
Financing Receivable, Impaired [Line Items]
Recorded investment in impaired loans with no related allowance		$ 86	$ 121
Recorded investment in impaired loans with related allowance		129	155
Recorded investment total impaired loans		215	276
Unpaid principal balance		333	346
Related allowance for loan losses		31	27
Business loans | Commercial borrower
Financing Receivable, Impaired [Line Items]
Recorded investment in impaired loans with no related allowance		70	93
Recorded investment in impaired loans with related allowance		129	147
Recorded investment total impaired loans		199	240
Unpaid principal balance		315	307
Related allowance for loan losses		31	27
Business loans | Commercial borrower | Domestic loans
Financing Receivable, Impaired [Line Items]
Recorded investment in impaired loans with no related allowance		30	50
Recorded investment in impaired loans with related allowance		120	130
Recorded investment total impaired loans		150	180
Unpaid principal balance		251	227
Related allowance for loan losses		30	24
Business loans | Commercial borrower | International loans
Financing Receivable, Impaired [Line Items]
Recorded investment in impaired loans with no related allowance			2
Recorded investment in impaired loans with related allowance			1
Recorded investment total impaired loans			3
Unpaid principal balance			8
Related allowance for loan losses			0
Business loans | Real estate mortgage | Commercial borrower | Domestic loans
Financing Receivable, Impaired [Line Items]
Recorded investment in impaired loans with no related allowance		40	41
Recorded investment in impaired loans with related allowance		9	16
Recorded investment total impaired loans		49	57
Unpaid principal balance		64	72
Related allowance for loan losses		1	3
Business loans | Real estate mortgage | Commercial borrower | Domestic loans | Commercial Real Estate business line
Financing Receivable, Impaired [Line Items]
Recorded investment in impaired loans with no related allowance	[1]	39	39
Recorded investment in impaired loans with related allowance	[1]	0	0
Recorded investment total impaired loans	[1]	39	39
Unpaid principal balance	[1]	49	49
Related allowance for loan losses	[1]	0	0
Business loans | Real estate mortgage | Commercial borrower | Domestic loans | Other business lines
Financing Receivable, Impaired [Line Items]
Recorded investment in impaired loans with no related allowance	[2]	1	2
Recorded investment in impaired loans with related allowance	[2]	9	16
Recorded investment total impaired loans	[2]	10	18
Unpaid principal balance	[2]	15	23
Related allowance for loan losses	[2]	1	3
Retail loans
Financing Receivable, Impaired [Line Items]
Recorded investment in impaired loans with no related allowance	[3]	16	28
Recorded investment in impaired loans with related allowance	[3]	0	8
Recorded investment total impaired loans	[3]	16	36
Unpaid principal balance	[3]	18	39
Related allowance for loan losses	[3]	0	0
Retail loans | Consumer borrower
Financing Receivable, Impaired [Line Items]
Recorded investment in impaired loans with no related allowance			12
Recorded investment in impaired loans with related allowance			0
Recorded investment total impaired loans			12
Unpaid principal balance			14
Related allowance for loan losses			0
Retail loans | Home equity | Consumer borrower
Financing Receivable, Impaired [Line Items]
Recorded investment in impaired loans with no related allowance		8	11
Recorded investment in impaired loans with related allowance		0	0
Recorded investment total impaired loans		8	11
Unpaid principal balance		10	13
Related allowance for loan losses		0	0
Retail loans | Other consumer | Consumer borrower
Financing Receivable, Impaired [Line Items]
Recorded investment in impaired loans with no related allowance			1
Recorded investment in impaired loans with related allowance			0
Recorded investment total impaired loans			1
Unpaid principal balance			1
Related allowance for loan losses			0
Retail loans | Residential mortgage
Financing Receivable, Impaired [Line Items]
Recorded investment in impaired loans with no related allowance		8	16
Recorded investment in impaired loans with related allowance		0	8
Recorded investment total impaired loans		8	24
Unpaid principal balance		8	25
Related allowance for loan losses		$ 0	$ 0
[1]	Primarily loans to real estate developers.
[2]	Primarily loans secured by owner-occupied real estate.
[3]	Individually evaluated retail loans generally have no related allowance for loan losses, primarily due to policy which results in direct write-downs of most restructured retail loans.

Credit Quality And Allowance_10

Credit Quality And Allowance For Credit Losses (Average Individually Evaluated Impaired Loans And Related Interest Recognized) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Financing Receivable, Impaired [Line Items]
Individually Evaluated Impaired Loans Average Balance for the Period		$ 242	$ 362	$ 551
Individually Evaluated Impaired Loans Interest Income Recognized for the Period		7	9	10
Business loans | Commercial borrower
Financing Receivable, Impaired [Line Items]
Individually Evaluated Impaired Loans Average Balance for the Period		212	329	511
Individually Evaluated Impaired Loans Interest Income Recognized for the Period		6	9	10
Business loans | Commercial borrower | Domestic loans
Financing Receivable, Impaired [Line Items]
Individually Evaluated Impaired Loans Average Balance for the Period		156	262	451
Individually Evaluated Impaired Loans Interest Income Recognized for the Period		2	5	8
Business loans | Commercial borrower | International loans
Financing Receivable, Impaired [Line Items]
Individually Evaluated Impaired Loans Average Balance for the Period		2	4	8
Individually Evaluated Impaired Loans Interest Income Recognized for the Period		0	0	0
Business loans | Commercial borrower | Real estate mortgage | Domestic loans
Financing Receivable, Impaired [Line Items]
Individually Evaluated Impaired Loans Average Balance for the Period		53	63	52
Individually Evaluated Impaired Loans Interest Income Recognized for the Period		4	4	2
Business loans | Commercial borrower | Real estate mortgage | Domestic loans | Commercial Real Estate business line
Financing Receivable, Impaired [Line Items]
Individually Evaluated Impaired Loans Average Balance for the Period	[1]	39	40	21
Individually Evaluated Impaired Loans Interest Income Recognized for the Period	[1]	3	4	2
Business loans | Commercial borrower | Real estate mortgage | Domestic loans | Other business lines
Financing Receivable, Impaired [Line Items]
Individually Evaluated Impaired Loans Average Balance for the Period	[2]	14	23	31
Individually Evaluated Impaired Loans Interest Income Recognized for the Period	[2]	1	0	0
Retail loans
Financing Receivable, Impaired [Line Items]
Individually Evaluated Impaired Loans Average Balance for the Period		30	33	40
Individually Evaluated Impaired Loans Interest Income Recognized for the Period		1	0	0
Retail loans | Residential mortgage
Financing Receivable, Impaired [Line Items]
Individually Evaluated Impaired Loans Average Balance for the Period		21	21	24
Individually Evaluated Impaired Loans Interest Income Recognized for the Period		1	0	0
Retail loans | Consumer borrower
Financing Receivable, Impaired [Line Items]
Individually Evaluated Impaired Loans Average Balance for the Period		9	12	16
Individually Evaluated Impaired Loans Interest Income Recognized for the Period		0	0	0
Retail loans | Consumer borrower | Home equity
Financing Receivable, Impaired [Line Items]
Individually Evaluated Impaired Loans Average Balance for the Period		9	11	13
Individually Evaluated Impaired Loans Interest Income Recognized for the Period		0	0	0
Retail loans | Consumer borrower | Other consumer
Financing Receivable, Impaired [Line Items]
Individually Evaluated Impaired Loans Average Balance for the Period		0	1	3
Individually Evaluated Impaired Loans Interest Income Recognized for the Period		0	0	0
Business Loans Member | Commercial borrower | Lease financing | Domestic loans
Financing Receivable, Impaired [Line Items]
Individually Evaluated Impaired Loans Average Balance for the Period		1	0	0
Individually Evaluated Impaired Loans Interest Income Recognized for the Period		$ 0	$ 0	$ 0
[1]	Primarily loans to real estate developers.
[2]	Primarily loans secured by owner-occupied real estate.

Credit Quality And Allowance_11

Credit Quality And Allowance For Credit Losses (Troubled Debt Restructurings By Type Of Modification) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018
Financing Receivable, Troubled Debt Restructuring [Line Items]
Recorded balance of troubled debt restructuring modified during the period		$ 29	$ 33
Business loans | Commercial borrower
Financing Receivable, Troubled Debt Restructuring [Line Items]
Recorded balance of troubled debt restructuring modified during the period		28	30
Business loans | Commercial borrower | Domestic loans
Financing Receivable, Troubled Debt Restructuring [Line Items]
Recorded balance of troubled debt restructuring modified during the period		28	27
Business loans | Commercial borrower | International loans | Other business lines
Financing Receivable, Troubled Debt Restructuring [Line Items]
Recorded balance of troubled debt restructuring modified during the period		0	1
Business loans | Commercial borrower | Real estate mortgage | Domestic loans | Other business lines
Financing Receivable, Troubled Debt Restructuring [Line Items]
Recorded balance of troubled debt restructuring modified during the period	[1]	0	2
Retail loans | Consumer borrower | Home equity
Financing Receivable, Troubled Debt Restructuring [Line Items]
Recorded balance of troubled debt restructuring modified during the period	[2]	1	3
Principal deferrals
Financing Receivable, Troubled Debt Restructuring [Line Items]
Recorded balance of troubled debt restructuring modified during the period	[3]	$ 28	$ 30
Minimum period loan terms were extended		90 days	90 days
Principal deferrals | Business loans | Commercial borrower
Financing Receivable, Troubled Debt Restructuring [Line Items]
Recorded balance of troubled debt restructuring modified during the period	[3]	$ 28	$ 30
Principal deferrals | Business loans | Commercial borrower | Domestic loans
Financing Receivable, Troubled Debt Restructuring [Line Items]
Recorded balance of troubled debt restructuring modified during the period	[3]	28	27
Principal deferrals | Business loans | Commercial borrower | International loans
Financing Receivable, Troubled Debt Restructuring [Line Items]
Recorded balance of troubled debt restructuring modified during the period	[3]	0	1
Principal deferrals | Business loans | Commercial borrower | Real estate mortgage | Domestic loans | Other business lines
Financing Receivable, Troubled Debt Restructuring [Line Items]
Recorded balance of troubled debt restructuring modified during the period	[1],[3]	0	2
Principal deferrals | Retail loans | Consumer borrower | Home equity
Financing Receivable, Troubled Debt Restructuring [Line Items]
Recorded balance of troubled debt restructuring modified during the period	[2],[3]	0	0
Interest Rate Reductions
Financing Receivable, Troubled Debt Restructuring [Line Items]
Recorded balance of troubled debt restructuring modified during the period		1	3
Interest Rate Reductions | Business loans | Commercial borrower
Financing Receivable, Troubled Debt Restructuring [Line Items]
Recorded balance of troubled debt restructuring modified during the period		0	0
Interest Rate Reductions | Business loans | Commercial borrower | Domestic loans
Financing Receivable, Troubled Debt Restructuring [Line Items]
Recorded balance of troubled debt restructuring modified during the period		0	0
Interest Rate Reductions | Business loans | Commercial borrower | International loans | Other business lines
Financing Receivable, Troubled Debt Restructuring [Line Items]
Recorded balance of troubled debt restructuring modified during the period		0	0
Interest Rate Reductions | Business loans | Commercial borrower | Real estate mortgage | Domestic loans | Other business lines
Financing Receivable, Troubled Debt Restructuring [Line Items]
Recorded balance of troubled debt restructuring modified during the period	[1]	0	0
Interest Rate Reductions | Retail loans | Consumer borrower | Home equity
Financing Receivable, Troubled Debt Restructuring [Line Items]
Recorded balance of troubled debt restructuring modified during the period	[2]	$ 1	$ 3
[1]	Primarily loans secured by owner-occupied real estate.
[2]	Includes bankruptcy loans for which the court has discharged the borrower's obligation and the borrower has not reaffirmed the debt.
[3]	Primarily represents loan balances where terms were extended 90 days or more at or above contractual interest rates. Also includes commercial loans restructured in bankruptcy.

Credit Quality And Allowance_12

Credit Quality And Allowance For Credit Losses Credit Quality And Allowance For Credit Losses (Troubled Debt Restructuring Subsequent Default) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Principal deferrals
Financing Receivable, Troubled Debt Restructuring [Line Items]
Subsequent default during period	$ 12	$ 0

Significant Group Concentrati_3

Significant Group Concentrations of Credit Risk Significant Group Concentrations of Credit Risk (Schedule of Automotive Industry Outstanding Loans and Total Exposure) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Concentration Risk [Line Items]
Total automotive loans	$ 8,663	$ 9,428
Total automotive exposure	12,035	12,440
Automotive Production
Concentration Risk [Line Items]
Total automotive loans	1,249	1,331
Total automotive exposure	2,358	2,396
Automotive Dealer
Concentration Risk [Line Items]
Total automotive loans	7,414	8,097
Total automotive exposure	$ 9,677	$ 10,044

Significant Group Concentrati_4

Significant Group Concentrations of Credit Risk Significant Group Concentrations of Credit Risk (Commercial Real Estate Exposure) (Details) - USD ($) $ in Millions		Dec. 31, 2019	Dec. 31, 2018
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans		$ 50,369	$ 50,163
Real estate construction loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans		3,455	3,077
Commercial mortgage loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans		9,559	9,106
Total commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans		13,014	12,183
Total unused commitments		3,557	3,146
Commercial Real Estate business line | Real estate construction loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	[1]	3,044	2,687
Commercial Real Estate business line | Commercial mortgage loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	[1]	2,176	1,743
Other business lines | Real estate construction loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	[2]	411	390
Other business lines | Commercial mortgage loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	[2]	$ 7,383	$ 7,363
[1]	Primarily loans to real estate developers.
[2]	Primarily loans secured by owner-occupied real estate.

Premises and Equipment (Narrati

Premises and Equipment (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Premises and Equipment [Abstract]
Rental expense for leased properties and equipment	$ 81	$ 75	$ 78

Premises and Equipment Summary

Premises and Equipment Summary of Premises and Equipment (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Land	$ 86	$ 85
Buildings and improvements	818	842
Furniture and equipment	513	492
Total cost	1,417	1,419
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	(960)	(944)
Premises and equipment	$ 457	$ 475

Derivative And Credit-Related_3

Derivative And Credit-Related Financial Instruments (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Fair value of securities pledged as collateral for derivative liabilities	$ 0
Cash received as collateral for derivative assets	12
Fair value of securities pledged as collateral for derivative assets	23
Cash posted as collateral for derivative liabilities	15
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	31	$ 30
Allowance for credit losses on lending-related commitments, unused commitments to extend credit	$ 25	24
Final year of expiration for outstanding letters of credit	2028
Risk participation agreements covering standby and commercial letters of credit	$ 161	136
Standby and commercial letters of credit outstanding	3,300	3,300
Carrying value of standby and commercial letters of credit included in accrued expenses and other liabilities	32	34
Deferred fees on standby and commercial letters of credit included in accrued expenses and other liabilities	26	28
Allowance for credit losses on lending-related commitments, amount related to standby and commercial letters of credit	6	6
Notional Amount of Derivative Credit Risk Participation Agreements	786	703
Maximum estimated exposure to credit risk participation agreements assuming 100% default	$ 20	$ 7
Weighted average remaining maturity of credit risk participation agreements, in years	3 years 4 months 24 days

Goodwill and Intangible Asset_2

Goodwill and Intangible Assets Goodwill and Intangible Assets (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Core deposit intangible
Amortization expense of core deposit intangible	$ 2	$ 2

Net Income Per Common Share (Ba

Net Income Per Common Share (Basic And Diluted Net Income Per Common Share) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Earnings Per Share [Abstract]
Net income	$ 269	$ 292	$ 298	$ 339	$ 310	$ 318	$ 281	$ 326	$ 1,198	$ 1,235	$ 743
Less income allocated to participating securities	2	2	1	2	2	2	2	2	7	8	5
Net income attributable to common shares	$ 267	$ 290	$ 297	$ 337	$ 308	$ 316	$ 279	$ 324	$ 1,191	$ 1,227	$ 738
Basic average common shares									150	168	174
Basic net income per common share	$ 1.87	$ 1.98	$ 1.95	$ 2.14	$ 1.91	$ 1.89	$ 1.62	$ 1.90	$ 7.95	$ 7.31	$ 4.23
Basic average common shares									150	168	174
Net effect of the assumed exercise of stock options									1	2	3
Net effect of the assumed exercise of warrants									0	1	1
Diluted average common shares									151	171	178
Diluted net income per common share	$ 1.85	$ 1.96	$ 1.94	$ 2.11	$ 1.88	$ 1.86	$ 1.59	$ 1.87	$ 7.87	$ 7.20	$ 4.14

Derivative And Credit-Related_4

Derivative And Credit-Related Financial Instruments (Schedule Of Derivative Instruments) (Details) - USD ($) $ in Millions		Dec. 31, 2019	Dec. 31, 2018
Derivatives, Fair Value [Line Items]
Notional/Contract Amount	[1]	$ 30,134	$ 21,557
Fair Value of Gross Derivative Assets		317	275
Fair Value of Gross Derivative Liabilities		141	269
Derivative assets, Netting adjustment - Offsetting derivative liabilities		(63)	(45)
Derivative liabilities, Netting adjustment - Offsetting derivative assets		(63)	(45)
Derivative assets, Netting adjustment - Cash collateral received		(11)	(174)
Derivative liabilities, Netting adjustment - Cash collateral posted		(12)	(1)
Net derivative assets included in consolidated balance sheets	[2]	243	56
Net derivative liabilities included in the consolidated balance sheet	[2]	66	223
Derivative assets, securities pledged as collateral		0	(1)
Derivative liabilities, securities pledged as collateral		(21)	0
Net derivative assets after deducting amounts not offset in the consolidated balance sheets		243	55
Net derivative liabilities after deducting amounts not offset in the consolidated balance sheets		45	223
Credit valuation adjustments for counterparty credit risk		9	2
Risk management purposes
Derivatives, Fair Value [Line Items]
Notional/Contract Amount	[1]	8,205	2,927
Fair Value of Gross Derivative Assets		0	1
Fair Value of Gross Derivative Liabilities		2	3
Risk management purposes | Derivatives designated as hedging instruments | Fair Value Hedging | Interest rate swap
Derivatives, Fair Value [Line Items]
Notional/Contract Amount	[1]	3,325	2,625
Fair Value of Gross Derivative Assets		0	0
Fair Value of Gross Derivative Liabilities		0	2
Risk management purposes | Derivatives designated as hedging instruments | Swaps - cash flow - receive fixed/pay floating rate | Interest rate swap
Derivatives, Fair Value [Line Items]
Notional/Contract Amount		4,550	0
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]
Notional/Contract Amount	[1]	330	302
Fair Value of Gross Derivative Assets		0	1
Fair Value of Gross Derivative Liabilities		2	1
Customer-initiated and other activities
Derivatives, Fair Value [Line Items]
Notional/Contract Amount	[1]	21,929	18,630
Fair Value of Gross Derivative Assets		317	274
Fair Value of Gross Derivative Liabilities		139	266
Customer-initiated and other activities | Interest rate contracts
Derivatives, Fair Value [Line Items]
Notional/Contract Amount	[1]	17,827	14,885
Fair Value of Gross Derivative Assets		211	67
Fair Value of Gross Derivative Liabilities		39	68
Customer-initiated and other activities | Interest rate caps and floors written
Derivatives, Fair Value [Line Items]
Notional/Contract Amount	[1]	671	885
Fair Value of Gross Derivative Assets		0	0
Fair Value of Gross Derivative Liabilities		0	1
Customer-initiated and other activities | Interest rate caps and floors purchased
Derivatives, Fair Value [Line Items]
Notional/Contract Amount	[1]	671	885
Fair Value of Gross Derivative Assets		0	1
Fair Value of Gross Derivative Liabilities		0	0
Customer-initiated and other activities | Interest rate swap
Derivatives, Fair Value [Line Items]
Notional/Contract Amount	[1]	16,485	13,115
Fair Value of Gross Derivative Assets		211	66
Fair Value of Gross Derivative Liabilities		39	67
Customer-initiated and other activities | Energy contracts
Derivatives, Fair Value [Line Items]
Notional/Contract Amount	[1]	3,089	2,650
Fair Value of Gross Derivative Assets		96	189
Fair Value of Gross Derivative Liabilities		92	186
Customer-initiated and other activities | Energy caps and floors written
Derivatives, Fair Value [Line Items]
Notional/Contract Amount	[1]	477	278
Fair Value of Gross Derivative Assets		0	0
Fair Value of Gross Derivative Liabilities		23	26
Customer-initiated and other activities | Energy caps and floors purchased
Derivatives, Fair Value [Line Items]
Notional/Contract Amount	[1]	477	278
Fair Value of Gross Derivative Assets		23	26
Fair Value of Gross Derivative Liabilities		0	0
Customer-initiated and other activities | Energy swaps
Derivatives, Fair Value [Line Items]
Notional/Contract Amount	[1]	2,135	2,094
Fair Value of Gross Derivative Assets		73	163
Fair Value of Gross Derivative Liabilities		69	160
Customer-initiated and other activities | Foreign exchange spot, options and swaps
Derivatives, Fair Value [Line Items]
Notional/Contract Amount	[1]	1,013	1,095
Fair Value of Gross Derivative Assets		10	18
Fair Value of Gross Derivative Liabilities		$ 8	$ 12
[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 on 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 $9 million and $2 million at December 31, 2019 and 2018 , respectively.

Goodwill and Intangible Asset_3

Goodwill and Intangible Assets Goodwill and Intangible Assets (Summary of Changes in Carrying Value of Goodwill) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Goodwill [Line Items]
Balance	$ 635	$ 635
Business Bank
Goodwill [Line Items]
Balance	473	473
Retail Bank
Goodwill [Line Items]
Balance	101	101
Wealth Management
Goodwill [Line Items]
Balance	$ 61	$ 61

Net Income Per Common Share (Sc

Net Income Per Common Share (Schedule of Average Shares Excluded From Diluted Net Income Per Common Share Computation) (Details) - Stock Options - $ / shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Average outstanding options	542,786	193,248	0
Minimum
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Range of exercise prices	$ 67.53	$ 95.25
Maximum
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Range of exercise prices	$ 95.25	$ 95.25

Derivative And Credit-Related_5

Derivative And Credit-Related Financial Instruments Derivative And Credit-Related Financial Instruments (Schedule of Effects of Fair Value Hedging on the Consolidated Statements of Comprehensive Income) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019		Dec. 31, 2018		Dec. 31, 2017
Statement [Line Items]
Document Period End Date	Dec. 31, 2019
Interest on medium- and long-term debt	$ 197	[1]	$ 144	[1]	$ 76
Swaps - fair value - receive fixed/pay floating | Risk management purposes | Interest Rate Swap [Member]
Statement [Line Items]
Interest rate contract: Hedged items interest expense	110		74
Interest rate contracts: Derivatives designated as hedging instruments net interest income	$ (4)		$ (7)
[1]	Includes the effects of hedging.

Goodwill and Intangible Asset_4

Goodwill and Intangible Assets Goodwill and Intangible Assets (Summary of CDI Carrying Value and Amortization) (Details) - Core deposit intangible - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Acquired Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	$ 34	$ 34
Accumulated amortization	(32)	(30)
Net carrying amount	$ 2	$ 4

Derivative And Credit-Related_6

Derivative And Credit-Related Financial Instruments (Schedule Of Weighted Average Maturity And Interest Rates On Risk Management Interest Rate Swaps) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018
Notional Amount	[1]	$ 30,134	$ 21,557
Cumulative hedging adjustments		146	49
Cumulative hedging adjustments on discontinued cash flow hedge		7	8
Risk management purposes
Notional Amount	[1]	8,205	2,927
Variable rate loans | Swaps - cash flow - receive fixed/pay floating rate | Risk management purposes | Cash flow swap
Notional Amount		$ 4,550
Weighted Average Remaining Maturity		3 years
Weighted Average Receive Rate		1.94%
Weighted Average Pay Rate	[2]	1.71%
Medium- and long-term debt | Swaps - fair value - receive fixed/pay floating | Risk management purposes | Interest rate swap
Notional Amount		$ 3,325	2,625
Carrying Value of Hedged Item	[3]	$ 3,469	$ 2,663
Weighted Average Remaining Maturity		4 years 7 months 6 days	3 years 10 months 24 days
Weighted Average Receive Rate		3.44%	3.40%
Weighted Average Pay Rate	[2]	2.80%	3.45%
[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 on the Consolidated Balance Sheets.
[2]	Variable rates paid on receive fixed swaps designated as fair value and cash flow hedges are based on one- and six-month LIBOR rates in effect at December 31, 2019 and 2018 .
[3]	Included $146 million and $49 million of cumulative hedging adjustments at December 31, 2019 and 2018 , respectively, which included $7 million and $8 million , respectively, of hedging adjustment on a discontinued hedging relationship.

Goodwill and Intangible Asset_5

Goodwill and Intangible Assets Goodwill and Intangible Assets (Schedule of Core Deposit Intangible Estimated Future Amortization Expense (Details) - Core deposit intangible - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Acquired Finite-Lived Intangible Assets [Line Items]
2020	$ 1
2021	1
Total	$ 2	$ 4

Derivative And Credit-Related_7

Derivative And Credit-Related Financial Instruments (Schedule Of Net Gains Recognized In Income On Customer-Initiated Derivatives) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Derivative Instruments, Gain (Loss) [Line Items]
Document Period End Date	Dec. 31, 2019
Customer-initiated and other activities
Derivative Instruments, Gain (Loss) [Line Items]
Net derivative gain recognized in income	$ 77	$ 77
Interest rate contracts | Customer-initiated and other activities | Other noninterest income
Derivative Instruments, Gain (Loss) [Line Items]
Net derivative gain recognized in income	29	26
Energy contracts | Customer-initiated and other activities | Other noninterest income
Derivative Instruments, Gain (Loss) [Line Items]
Net derivative gain recognized in income	5	4
Foreign exchange contracts | Customer-initiated and other activities | Foreign exchange income
Derivative Instruments, Gain (Loss) [Line Items]
Net derivative gain recognized in income	$ 43	$ 47

Derivative And Credit-Related_8

Derivative And Credit-Related Financial Instruments (Schedule Of Financial Instruments With Off-Balance Sheet Credit Risk) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Document Period End Date	Dec. 31, 2019
Maximum | Unused Commitments to Extend Credit
Loss contingency, estimate of possible loss, maximum	$ 26,861	$ 27,267
Maximum | Commercial And Other | Unused Commitments to Extend Credit
Loss contingency, estimate of possible loss, maximum	23,681	24,266
Maximum | Bankcard, Revolving Check Credit And Home Equity Loan Commitments | Unused Commitments to Extend Credit
Loss contingency, estimate of possible loss, maximum	3,180	3,001
Maximum | Standby Letters Of Credit
Loss contingency, estimate of possible loss, maximum	3,320	3,244
Maximum | Commercial Letters Of Credit
Loss contingency, estimate of possible loss, maximum	$ 18	$ 39

Derivative And Credit-Related_9

Derivative And Credit-Related Financial Instruments (Summary Of Criticized Letters Of Credit) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Document Period End Date	Dec. 31, 2019
Total criticized standby and commercial letters of credit	$ 44	$ 49
As a percentage of total outstanding standby and commercial letters of credit	1.30%	1.50%

Variable Interest Entities (V_3

Variable Interest Entities (VIEs) (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Variable Interest Entity [Line Items]
Unfunded commitments to fund tax credit entities	$ 160
Amount of financial or other support not contractually required provided by the Corporation to VIEs	0	$ 0	$ 0
Low Income Housing Tax Credit Entities
Variable Interest Entity [Line Items]
Exposure to loss as a result of involvement with VIEs	441
Other Tax Credit Entities
Variable Interest Entity [Line Items]
Exposure to loss as a result of involvement with VIEs	$ 6

Variable Interest Entities (V_4

Variable Interest Entities (VIEs) (Impact Of VIEs On The Consolidated Statements Of Comprehensive Income) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Variable Interest Entity [Line Items]
Other noninterest income									$ 109	$ 96	$ 108
Provision for income taxes	$ 82	$ 80	$ 87	$ 85	$ 90	$ 63	$ 54	$ 93	334	300	491
Variable Interest Entity
Variable Interest Entity [Line Items]
Other noninterest income									2	5	2
Provision for income taxes									(10)	(11)	(20)
Low income housing tax credits | Variable Interest Entity
Variable Interest Entity [Line Items]
Provision for income taxes, amortization of LIHTC investments									65	65	67
Provision for income taxes, affordable housing tax credits and other tax benefits									(62)	(62)	(63)
Other tax benefits related to tax credit entities | Variable Interest Entity
Variable Interest Entity [Line Items]
Provision for income taxes, affordable housing tax credits and other tax benefits									$ (13)	$ (14)	$ (24)

Deposits Deposits (Narrative) (

Deposits Deposits (Narrative) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Deposits [Abstract]
Domestic certificates of deposit of $250,000 or more	$ 956	$ 543
Foreign office time deposits in denominations of $250,000 or more	$ 91	$ 8

Deposits Deposits (Schedule of

Deposits Deposits (Schedule of Maturities of Certificates of Deposit and Other Deposits with a Stated Maturity) (Details) $ in Millions	Dec. 31, 2019USD ($)
Deposits [Abstract]
2020	$ 2,970
2021	156
2022	24
2023	15
2024	11
Thereafter	26
Total	$ 3,202

Deposits Deposits (Schedule o_2

Deposits Deposits (Schedule of Maturities of Domestic Deposits of One Hundred Thousand or More) (Details) - Domestic certificates of deposit and other deposits - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Three Months or Less	$ 398	$ 363
Over three months to six months	503	146
Over six months to twelve months	819	278
Over twelve months	97	297
Total	$ 1,817	$ 1,084

Short-term Borrowings Short-t_2

Short-term Borrowings Short-term Borrowings (Narrative) (Details) $ in Billions	Dec. 31, 2019USD ($)
Short-term Debt [Abstract]
Pledged loans to provide collateralized borrowing with the FRB	$ 22
Available collateralized borrowing with the FRB	$ 17.8

Short-term Borrowings Short-t_3

Short-term Borrowings Short-term Borrowings (Summary of Short-term Borrowings) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Short-term Debt [Line Items]
Amount outstanding at year-end	$ 71	$ 44
Federal Funds Purchased and Securities Sold Under Agreements to Repurchase
Short-term Debt [Line Items]
Amount outstanding at year-end	$ 71	$ 44	$ 10
Weighted average interest rate at year-end	1.50%	2.39%	1.43%
Maximum month-end balance during the year	$ 835	$ 182	$ 41
Average balance outstanding during the year	$ 113	$ 59	$ 20
Weighted average interest rate during the year	2.28%	1.91%	1.02%
Other Short-term Borrowings
Short-term Debt [Line Items]
Amount outstanding at year-end	$ 0	$ 0	$ 0
Weighted average interest rate at year-end	0.00%	0.00%	0.00%
Maximum month-end balance during the year	$ 1,200	$ 250	$ 1,024
Average balance outstanding during the year	$ 256	$ 3	$ 257
Weighted average interest rate during the year	2.44%	1.75%	1.15%

Medium- And Long-Term Debt (Nar

Medium- And Long-Term Debt (Narrative) (Details) - USD ($) $ in Millions		Dec. 31, 2019		Aug. 01, 2019	Jul. 23, 2019	Feb. 01, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Unamortized debt issuance costs		$ 12					$ 8
Parent Company
Debt Instrument [Line Items]
Medium- and long-term notes		1,471					1,209
Subsidiaries
Debt Instrument [Line Items]
Medium- and long-term notes		1,172					663
Long-term Federal Home Loan Bank advances		3,800					3,800
Blanket lien on real-estate related loans securing FHLB advances		17,200
Potential FHLB borrowing capacity		5,100
4.00% notes due 2029 | Parent Company
Debt Instrument [Line Items]
Medium- and long-term notes		$ 587	[1]	$ 200		$ 350	0	[1]
Stated interest rate		4.00%				4.00%
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
Weighted-average interest rate		1.70%
Floating-rate based on FHLB auction rate due 2028 | Subsidiaries
Debt Instrument [Line Items]
Long-term Federal Home Loan Bank advances		$ 1,000					1,000
Weighted-average interest rate		1.88%
3.70% notes due 2023 | Parent Company
Debt Instrument [Line Items]
Medium- and long-term notes	[1]	$ 884					861
Stated interest rate		3.70%
2.50% notes due 2024 | Subsidiaries
Debt Instrument [Line Items]
Medium- and long-term notes		$ 498	[1]		$ 500		$ 0	[1]
Stated interest rate					2.50%
[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.

Medium- And Long-Term Debt (Sch

Medium- And Long-Term Debt (Schedule Of Medium- And Long-Term Debt) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2019		Dec. 31, 2018		Aug. 01, 2019	Jul. 23, 2019	Feb. 01, 2019
Debt Instrument [Line Items]
Total medium- and long-term debt		$ 7,269		$ 6,463
Parent Company
Debt Instrument [Line Items]
Medium- and long-term notes		1,471		1,209
Total medium- and long-term debt		1,735		1,459
Subsidiaries
Debt Instrument [Line Items]
Subordinated notes		562		541
Medium- and long-term notes		1,172		663
Long-term Federal Home Loan Bank advances		3,800		3,800
Total medium- and long-term debt		5,534		5,004
3.80% subordinated notes due 2026 | Parent Company
Debt Instrument [Line Items]
Subordinated notes	[1]	$ 264		$ 250
Stated interest rate		3.80%		3.80%
Maturity date		Jul. 22, 2026		Jul. 22, 2026
2.125% notes due 2019 | Parent Company
Debt Instrument [Line Items]
Medium- and long-term notes	[1]	$ 0		$ 348
Stated interest rate		2.125%		2.125%
Maturity date		May 23, 2019		May 23, 2019
3.70% notes due 2023 | Parent Company
Debt Instrument [Line Items]
Medium- and long-term notes	[1]	$ 884		$ 861
Stated interest rate		3.70%
Maturity date		Jul. 31, 2023
4.00% notes due 2029 | Parent Company
Debt Instrument [Line Items]
Medium- and long-term notes		$ 587	[1]	0	[1]	$ 200		$ 350
Stated interest rate		4.00%						4.00%
Maturity date		Feb. 1, 2029
4.00% subordinated notes due 2025 | Subsidiaries
Debt Instrument [Line Items]
Subordinated notes	[1]	$ 360		$ 343
Stated interest rate		4.00%		4.00%
Maturity date		Jul. 27, 2025		Jul. 27, 2025
7.875% subordinated notes due 2026 | Subsidiaries
Debt Instrument [Line Items]
Subordinated notes	[1]	$ 202		$ 198
Stated interest rate		7.875%		7.875%
Maturity date		Sep. 15, 2026		Sep. 15, 2026
2.50% notes due 2020 | Subsidiaries
Debt Instrument [Line Items]
Medium- and long-term notes	[1]	$ 674		$ 663
Stated interest rate		2.50%		2.50%
Maturity date		Jun. 2, 2020		Jun. 2, 2020
2.50% notes due 2024 | Subsidiaries
Debt Instrument [Line Items]
Medium- and long-term notes		$ 498	[1]	$ 0	[1]		$ 500
Stated interest rate							2.50%
Maturity date		Jul. 23, 2024
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
Weighted-average interest rate		1.70%
Floating-rate based on FHLB auction rate due 2026 | Subsidiaries | Maximum
Debt Instrument [Line Items]
Maturity date		May 20, 2026
Floating-rate based on FHLB auction rate due 2026 | Subsidiaries | Minimum
Debt Instrument [Line Items]
Maturity date		Mar. 4, 2026
Floating-rate based on FHLB auction rate due 2028 | Subsidiaries
Debt Instrument [Line Items]
Long-term Federal Home Loan Bank advances		$ 1,000		$ 1,000
Maturity date		Jan. 26, 2028
Weighted-average interest rate		1.88%
[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.

Medium- And Long-Term Debt Sche

Medium- And Long-Term Debt Schedule of Maturities of Medium- and Long-term Debt (Details) $ in Millions	Dec. 31, 2019USD ($)
Debt Disclosure [Abstract]
2020	$ 675
2021	0
2022	0
2023	850
2024	500
Thereafter	5,100
Total	$ 7,125

Shareholders' Equity Shareholde

Shareholders' Equity Shareholders' Equity (Narrative) (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Stock Option
Common stock shares reserved for future issuance	3,800,000
Restricted Stock
Shares of non-vested restricted stock outstanding	458,000	869,000
Common Stock
Shares repurchased under equity repurchase program	(18,700,000)	(14,900,000)	(7,500,000)
Warrants
Year of expiration for outstanding warrants	2018
Shares of common stock issued upon exercise of warrants		585,000	1,800,000
Equity Repurchase Program | Common Stock
Shares repurchased under equity repurchase program	18,600,000		7,300,000
Average cost per share of shares repurchased under equity repurchase program	$ 73.60	$ 89.21	$ 72.44
Stock repurchased during the period	$ 1,400

Accumulated Other Comprehensi_3

Accumulated Other Comprehensive Loss (Schedule Of Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019		Dec. 31, 2018	Dec. 31, 2017
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Investment securities, Balance at beginning of period, net of tax	$ (138)		$ (101)	$ (33)
Cumulative effect of change in accounting principle	0		1	0
Net unrealized holding gains (losses) arising during the period	257		(69)	(81)
Investment securities, Less: Benefit for income taxes	60		(16)	(27)
Investment securities, Net unrealized holding losses arising during period, net of tax	197		(53)	(54)
Investment securities, Net realized (losses) gains included in net securities (losses) gains	(8)		(20)	0
Investment securities, Less: Benefit for income taxes	(2)		(5)	0
Investment securities, Reclassification adjustment for net securities (losses) gains included in net income, net of tax	(6)		(15)	0
Investment securities, Net losses realized as a yield adjustment in interest on investment securities	0		0	(3)
Investment securities, Less: Benefit for income taxes	0		0	(1)
Investment securities, Reclassification adjustment for net losses realized as a yield adjustment included in net income, net of tax	0		0	(2)
Investment securities, Change in net unrealized losses on investment securities, net of tax	203		(38)	(52)
Investment securities, Reclassification of certain deferred tax effects	0		0	(16)	[1]
Investment securities, Balance at end of period, net of tax	65		(138)	(101)
Cash Flow Hedges, Balance at beginning of period, net of tax	0		0	0
Cash flow hedges, Net gain arising during the period	44		0	0
Cash flow hedges, Less: Provision for income tax	10		0	0
Change in net cash flow hedges gains, net of tax	34		0	0
Cash Flow Hedges, Balance at end of period, net of tax	34	[2]	0	0
Benefit plans, Balance at beginning of period, net of tax	(471)		(350)	(350)
Benefit plans, Actuarial loss arising during the period	163		(191)	72
Benefit plans, Less: Provision (benefit) for income taxes	38		(44)	17
Benefit plans, Net defined benefit pension and other postretirement adjustment arising during the period, net of tax	125		(147)	55
Benefit plans, Amortization of actuarial net loss	42		61	51
Benefit plans, Amortization of prior service (credit) cost	(27)		(27)	(27)
Benefit plans, Total amounts recognized in employee benefits expense	15		34	24
Benefit plans, Less: Provision for income taxes	3		8	8
Benefit plans, Adjustment for amounts recognized as components of net periodic benefit cost during the period, net of tax	12		26	16
Benefit plans, Change in defined benefit pension and other postretirement plans adjustment, net of tax	137		(121)	71
Benefit plans, Reclassification of certain deferred tax effects	0		0	(71)	[1]
Benefit plans, Balance at end of period, net of tax	(334)		(471)	(350)
Total accumulated other comprehensive loss at end of period, net of tax	$ (235)		$ (609)	$ (451)
[1]	Amounts reclassified to retained earnings due to early adoption of ASU 2018-02. For further information, refer to Note 1.
[2]	Return on average assets is calculated based on the greater of average assets or average liabilities and attributed equity.

Share-Based Compensation Shar_2

Share-Based Compensation Share-Based Compensation (Narrative) (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Number of shares originally available for grant	6,100,000
Shares available for grant	5,000,000
Closing stock price per share	$ 71.75
Total intrinsic value of stock options exercised	$ 20	$ 81	$ 104
Shares in treasury	86,069,234	68,081,176
Restricted Stock
Total fair value of restricted stock awards that fully vested	$ 15	$ 14	19
Restricted Stock | Minimum
Share-based compensation vesting period	3 years
Restricted Stock | Maximum
Share-based compensation vesting period	5 years
Restricted Stock Units (RSUs)
Total fair value of restricted stock awards that fully vested	$ 14	$ 10	$ 10
Restricted Stock Units (RSUs) | Minimum
Share-based compensation vesting period	3 years
Restricted Stock Units (RSUs) | Maximum
Share-based compensation vesting period	5 years
Stock Options | Minimum
Share-based compensation vesting period	1 year
Stock Options | Maximum
Share-based compensation vesting period	4 years

Share-Based Compensation (Summa

Share-Based Compensation (Summary of Components of Share-Based Compensation Expense) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Share-based Payment Arrangement, Noncash Expense [Abstract]
Total share-based compensation expense	$ 39	$ 48	$ 39
Related tax benefits recognized in net income	$ 9	$ 11	$ 14

Share-Based Compensation (Unrec

Share-Based Compensation (Unrecognized Compensation Expense) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2019USD ($)
Share-based Payment Arrangement, Noncash Expense [Abstract]
Total unrecognized share-based compensation expense	$ 33
Weighted-average expected recognition period (in years)	2 years 3 months 7 days

Share-Based Compensation (Estim

Share-Based Compensation (Estimated Weighted-Average Grant-Date Fair Value Per Option Share and the Underlying Binomial Option-Pricing Model Assumptions) (Details) - $ / shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Share-based Payment Arrangement, Noncash Expense [Abstract]
Weighted-average grant-date fair value per option	$ 22.27	$ 30.32	$ 19.61
Risk-free interest rates	2.74%	2.63%	2.47%
Expected dividend yield	3.00%	3.00%	3.00%
Expected volatility factors of the market price of Comerica common stock	30.00%	36.00%	34.00%
Expected option life (in years)	7 years 7 months 6 days	7 years 4 months 24 days	6 years 10 months 24 days

Share-Based Compensation (Sum_2

Share-Based Compensation (Summary of the Corporation's Stock Option Activity and Related Information) (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Shares in treasury	86,069,234	68,081,176
Stock Options
Number of options outstanding at January 1, 2017	2,943,000
Options granted	283,000
Options forfeited or expired	(35,000)
Options exercised	(511,000)
Number of options outstanding at December 31, 2017	2,680,000
Number of options exercisable at December 31, 2017	1,816,000
Options outstanding at January 1, 2017 (Weighted-average exercise price)	$ 44.70
Options granted (Weighted-average exercise price)	80.14
Options forfeited or expired (Weighted-average exercise price)	65.91
Options exercised (Weighted-average exercise price)	37.32
Options outstanding at December 31, 2017 (Weighted-average exercise price)	49.58
Options exercisable at December 31, 2017 (Weighted-average exercise price)	$ 41.79
Weighted-average remaining contractual term in years at December 31, 2017	5 years 3 months 18 days
Weighted-average remaining contractual term in years exercisable at December 31, 2017	4 years 2 months 12 days
Aggregate intrinsic value outstanding at December 31, 2017	$ 66
Aggregate intrinsic value exercisable at December 31, 2017	$ 56

Share-Based Compensation (Sum_3

Share-Based Compensation (Summary of the Corporation's Restricted Stock Activity and Related Information) (Details) - Restricted Stock	12 Months Ended
	Dec. 31, 2019$ / sharesshares
Non-vested shares outstanding at January 1, 2018 | shares	869,000
Non-vested shares forfeited | shares	(27,000)
Shares vested | shares	(384,000)
Non-vested shares outstanding at December 31, 2018 | shares	458,000
Non-vested shares outstanding at January 1, 2017 (Weighted-average grant-date fair value) | $ / shares	$ 44.34
Non-vested shares forfeited (Weighted-average grant-date fair value) | $ / shares	49.81
Shares vested (Weighted-average grant-date fair value) | $ / shares	38.81
Non-vested shares outstanding at December 31, 2017 (Weighted-average grant-date fair value) | $ / shares	$ 48.64

Share-Based Compensation Summar

Share-Based Compensation Summary of the Corporation's Restricted Stock Unit Activity and Related Information (Details) - Restricted Stock Units (RSUs) shares in Thousands	12 Months Ended
	Dec. 31, 2019$ / sharesshares
Service-Based Units
Non-vested shares outstanding at January 1, 2018 | shares	367
Non-vested shares granted | shares	237
Non-vested shares forfeited | shares	(14)
Shares vested | shares	(12)
Non-vested shares outstanding at December 31, 2018 | shares	578
Non-vested shares outstanding at January 1, 2017 (Weighted-average grant-date fair value) | $ / shares	$ 68.14
Non-vested shares granted (Weighted-average grant-date fair value) | $ / shares	78.81
Non-vested shares forfeited (Weighted-average grant-date fair value) | $ / shares	87.38
Shares vested (Weighted-average grant-date fair value) | $ / shares	55.81
Non-vested shares outstanding at December 31, 2017 (Weighted-average grant-date fair value) | $ / shares	$ 72.34
Performance-Based Units
Non-vested shares outstanding at January 1, 2018 | shares	662
Non-vested shares granted | shares	329
Non-vested shares forfeited | shares	(28)
Shares vested | shares	(420)
Non-vested shares outstanding at December 31, 2018 | shares	543
Non-vested shares outstanding at January 1, 2017 (Weighted-average grant-date fair value) | $ / shares	$ 56.64
Non-vested shares granted (Weighted-average grant-date fair value) | $ / shares	66.80
Non-vested shares forfeited (Weighted-average grant-date fair value) | $ / shares	81.06
Shares vested (Weighted-average grant-date fair value) | $ / shares	32.53
Non-vested shares outstanding at December 31, 2017 (Weighted-average grant-date fair value) | $ / shares	$ 80.22

Employee Benefit Plans (Narrati

Employee Benefit Plans (Narrative) (Details)	12 Months Ended
	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets in defined benefit pension plan	$ 2,949,000,000	$ 2,462,000,000
Effect of one percentage point increase on postretirement benefit obligation	0.05
Estimated employer contributions for defined benefit plans in year 2017	$ 0
Employer core matching cash contribution as percent of employee contribution	100.00%
Percent of qualified earnings contributed by employee matched by the Corporation	4.00%
Defined contribution plan expense	$ 22,000,000	21,000,000	$ 21,000,000
Profit sharing plan expense included in employee benefits expense	0	0	1,000,000
Qualified Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets in defined benefit pension plan	$ 2,933,000,000	2,458,000,000	2,747,000,000
Estimated average life of pension plan in years	12
Non-Qualified Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets in defined benefit pension plan	$ 0	0
Postretirement Benefit Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets in defined benefit pension plan	$ 57,000,000	$ 56,000,000	$ 60,000,000
Minimum | Qualified Plan | Debt securities
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Target allocation percent	0.45
Maximum | Qualified Plan | Debt securities
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Target allocation percent	0.55

Employee Benefit Plans (Reconci

Employee Benefit Plans (Reconciliations of Plan assets and the Projected Benefit Obligation, the Weighted-Average Assumptions Used to Determine Year-End Benefit Obligations, and the Amounts Recognized in Accumulated Other Comprehensive Income (Loss) (Details) - USD ($)		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Fair value of plan assets at January 1		$ 2,462,000,000
Fair value of plan assets at December 31		2,949,000,000	$ 2,462,000,000
Qualified Plan
Fair value of plan assets at January 1		2,458,000,000	2,747,000,000
Actual return on plan assets		579,000,000	(167,000,000)	$ 396,000,000
Employer contributions		0	0
Benefits paid		(104,000,000)	(122,000,000)
Fair value of plan assets at December 31		2,933,000,000	2,458,000,000	2,747,000,000
Projected benefit obligation at January 1		1,901,000,000	2,061,000,000
Service cost		31,000,000	29,000,000	29,000,000
Interest cost		80,000,000	75,000,000	78,000,000
Actuarial (gain) loss		223,000,000	(142,000,000)
Projected benefit obligation at December 31		2,131,000,000	1,901,000,000	2,061,000,000
Accumulated benefit obligation		2,121,000,000	1,893,000,000
Funded Status at December 31	[1],[2]	$ 802,000,000	$ 557,000,000
Weighted-average assumptions, discount rate, percent		3.43%	4.37%
Weighted-average assumptions, rate of compensation increase, percent		4.00%	4.00%
Accumulated other comprehensive income (loss), net actuarial loss		$ (463,000,000)	$ (687,000,000)
Accumulated other comprehensive income (loss), net prior service (cost) credit		121,000,000	140,000,000
Balance at December 31		(342,000,000)	(547,000,000)
Non-Qualified Plan
Fair value of plan assets at January 1		0
Benefits paid		(13,000,000)	(11,000,000)
Fair value of plan assets at December 31		0	0
Projected benefit obligation at January 1		211,000,000	212,000,000
Service cost		3,000,000	2,000,000	2,000,000
Interest cost		9,000,000	8,000,000	8,000,000
Actuarial (gain) loss		25,000,000	0
Projected benefit obligation at December 31		235,000,000	211,000,000	212,000,000
Accumulated benefit obligation		234,000,000	209,000,000
Funded Status at December 31	[1],[2]	$ (235,000,000)	$ (211,000,000)
Weighted-average assumptions, discount rate, percent		3.43%	4.37%
Weighted-average assumptions, rate of compensation increase, percent		4.00%	4.00%
Accumulated other comprehensive income (loss), net actuarial loss		$ (94,000,000)	$ (76,000,000)
Accumulated other comprehensive income (loss), net prior service (cost) credit		26,000,000	34,000,000
Balance at December 31		(68,000,000)	(42,000,000)
Postretirement Benefit Plan
Fair value of plan assets at January 1		56,000,000	60,000,000
Actual return on plan assets		5,000,000	(1,000,000)	2,000,000
Employer contributions		1,000,000	1,000,000
Benefits paid		(5,000,000)	(4,000,000)
Fair value of plan assets at December 31		57,000,000	56,000,000	60,000,000
Projected benefit obligation at January 1		46,000,000	51,000,000
Service cost		0	0
Interest cost		2,000,000	2,000,000	2,000,000
Actuarial (gain) loss		5,000,000	(3,000,000)
Projected benefit obligation at December 31		48,000,000	46,000,000	$ 51,000,000
Accumulated benefit obligation		48,000,000	46,000,000
Funded Status at December 31	[1],[2]	$ 9,000,000	$ 10,000,000
Weighted-average assumptions, discount rate, percent		3.26%	4.26%
Healthcare cost trend rate assumed for next year		6.25%	6.50%
Rate to which the healthcare cost trend rate is assumed to decline (the ultimate trend rate), percent		4.50%	4.50%	4.50%
Year when healthcare cost trend rate reaches the ultimate trend rate		2027	2027
Accumulated other comprehensive income (loss), net actuarial loss		$ (20,000,000)	$ (19,000,000)
Accumulated other comprehensive income (loss), net prior service (cost) credit		1,000,000	1,000,000
Balance at December 31		$ (19,000,000)	$ (18,000,000)
[1]	Based on projected benefit obligation for defined benefit pension plans and accumulated benefit obligation for postretirement benefit plan.
[2]	The Corporation recognizes the overfunded and underfunded status of the plans in accrued income and other assets and accrued expenses and other liabilities, respectively, on the Consolidated Balance Sheets.

Employee Benefit Plans (Schedul

Employee Benefit Plans (Schedule of Changes, Net of Tax, in Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Actuarial gain (loss) arising during the period	$ 163	$ (191)	$ 72
Amortization of net actuarial loss	42	61	51
Amortization of prior service credit	(27)	(27)	(27)
Total recognized in other comprehensive income (loss)	178	$ (157)	$ 96
Qualified Plan
Actuarial gain (loss) arising during the period	190
Amortization of net actuarial loss	34
Amortization of prior service credit	(19)
Total recognized in other comprehensive income (loss)	205
Non-Qualified Plan
Actuarial gain (loss) arising during the period	(25)
Amortization of net actuarial loss	7
Amortization of prior service credit	(8)
Total recognized in other comprehensive income (loss)	(26)
Postretirement Benefit Plan
Actuarial gain (loss) arising during the period	(2)
Amortization of net actuarial loss	1
Amortization of prior service credit	0
Total recognized in other comprehensive income (loss)	$ (1)

Employee Benefit Plans Employee

Employee Benefit Plans Employee Benefit Plans (Net Periodic Defined Benefit Cost) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Net periodic defined benefit credit	$ (29)	$ (18)	$ (18)
Qualified Plan
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate	3.43%	4.37%
Service cost	$ 31	$ 29	29
Interest cost	80	75	78
Expected return on plan assets	(166)	(165)	(159)
Amortization of prior service (credit) cost	(19)	(19)	(19)
Amortization of net loss	34	51	43
Total other components of net benefit credit or cost	(71)	(58)	(57)
Net periodic defined benefit credit	(40)	(29)	(28)
Actual return on plan assets	$ 579	$ (167)	$ 396
Actual rate of return on plan assets, percent	24.07%	(6.21%)	16.48%
Weighted-average assumptions, discount rate, percent	4.37%	3.74%	4.23%
Weighted-average assumptions, expected long-term return on plan assets, percent	6.50%	6.50%	6.50%
Weighted-average assumptions, rate of compensation increase, percent	4.00%	3.75%	3.50%
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Rate of Compensation Increase	4.00%	4.00%
Non-Qualified Plan
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate	3.43%	4.37%
Service cost	$ 3	$ 2	$ 2
Interest cost	9	8	8
Expected return on plan assets	0	0	0
Amortization of prior service (credit) cost	(8)	(8)	(8)
Amortization of net loss	7	9	8
Total other components of net benefit credit or cost	8	9	8
Net periodic defined benefit credit	$ 11	$ 11	$ 10
Weighted-average assumptions, discount rate, percent	4.37%	3.74%	4.23%
Weighted-average assumptions, rate of compensation increase, percent	4.00%	3.75%	3.50%
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Rate of Compensation Increase	4.00%	4.00%
Postretirement Benefit Plan
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate	3.26%	4.26%
Service cost	$ 0	$ 0
Interest cost	2	2	$ 2
Expected return on plan assets	(3)	(3)	(3)
Amortization of net loss	1	1	1
Net periodic defined benefit credit	0	0	0
Actual return on plan assets	$ 5	$ (1)	$ 2
Actual rate of return on plan assets, percent	9.14%	(2.05%)	3.52%
Weighted-average assumptions, discount rate, percent	4.26%	3.55%	3.92%
Weighted-average assumptions, expected long-term return on plan assets, percent	5.00%	5.00%	5.00%
Health care cost trend rate assumed	6.50%	6.50%	6.50%
Rate to which the healthcare cost trend rate is assumed to decline (the ultimate trend rate), percent	4.50%	4.50%	4.50%
Defined Benefit Plan Year That Reaches Ultimate Trend Rate In Current Expense	2027	2027	2027
Defined Benefit Plan, Year Health Care Cost Trend Rate Reaches Ultimate Trend Rate	2027	2027
Defined Benefit Plan, Health Care Cost Trend Rate Assumed, Next Fiscal Year	6.25%	6.50%

Employee Benefit Plans (The Est

Employee Benefit Plans (The Estimated Portion of Balances Remaining in Accumulated Other Comprehensive Income (Loss) that are Expected to be Recognized as a Component of Net Periodic Benefit Cost) (Details) $ in Millions	Dec. 31, 2019USD ($)
Net loss	$ 64
Prior service credit	(27)
Qualified Plan
Net loss	54
Prior service credit	(19)
Non-Qualified Plan
Net loss	9
Prior service credit	(8)
Postretirement Benefit Plan
Net loss	1
Prior service credit	$ 0

Employee Benefit Plans (Fair Va

Employee Benefit Plans (Fair Values of the Corporation's Qualified Defined Benefit Pension Plan Investments Measured at Fair Value on a Recurring Basis) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Fair value of plan assets in qualified defined benefit pension plan, Excluding assets valued at net asset value	$ 2,480	$ 2,070
Fair value of plan assets in qualified defined benefit pension plan	2,949	2,462
Cash equivalent securities | Commercial paper
Fair value of plan assets in qualified defined benefit pension plan		3
Equity securities | Mutual funds
Fair value of plan assets in qualified defined benefit pension plan	2
Equity securities | Common stock
Fair value of plan assets in qualified defined benefit pension plan	1,086	803
Debt securities | U.S. Treasury and other U.S. government agency securities
Fair value of plan assets in qualified defined benefit pension plan	574	496
Debt securities | Corporate and municipal bonds and notes
Fair value of plan assets in qualified defined benefit pension plan	734	679
Debt securities | Collateralized mortgage obligations
Fair value of plan assets in qualified defined benefit pension plan	27	29
Debt securities | Collective investments funds
Fair value of plan assets in qualified defined benefit pension plan	469	392
Private placements
Fair value of plan assets in qualified defined benefit pension plan	57	60
Level 1
Fair value of plan assets in qualified defined benefit pension plan, Excluding assets valued at net asset value	1,639	1,288
Level 1 | Cash equivalent securities | Commercial paper
Fair value of plan assets in qualified defined benefit pension plan		3
Level 1 | Equity securities | Mutual funds
Fair value of plan assets in qualified defined benefit pension plan	2
Level 1 | Equity securities | Common stock
Fair value of plan assets in qualified defined benefit pension plan	1,086	803
Level 1 | Debt securities | U.S. Treasury and other U.S. government agency securities
Fair value of plan assets in qualified defined benefit pension plan	551	482
Level 1 | Debt securities | Corporate and municipal bonds and notes
Fair value of plan assets in qualified defined benefit pension plan	0	0
Level 1 | Debt securities | Collateralized mortgage obligations
Fair value of plan assets in qualified defined benefit pension plan	0	0
Level 1 | Private placements
Fair value of plan assets in qualified defined benefit pension plan	0	0
Level 2
Fair value of plan assets in qualified defined benefit pension plan, Excluding assets valued at net asset value	784	722
Level 2 | Cash equivalent securities | Commercial paper
Fair value of plan assets in qualified defined benefit pension plan		0
Level 2 | Equity securities | Mutual funds
Fair value of plan assets in qualified defined benefit pension plan	0
Level 2 | Equity securities | Common stock
Fair value of plan assets in qualified defined benefit pension plan	0	0
Level 2 | Debt securities | U.S. Treasury and other U.S. government agency securities
Fair value of plan assets in qualified defined benefit pension plan	23	14
Level 2 | Debt securities | Corporate and municipal bonds and notes
Fair value of plan assets in qualified defined benefit pension plan	734	679
Level 2 | Debt securities | Collateralized mortgage obligations
Fair value of plan assets in qualified defined benefit pension plan	27	29
Level 2 | Private placements
Fair value of plan assets in qualified defined benefit pension plan	0	0
Level 3
Fair value of plan assets in qualified defined benefit pension plan, Excluding assets valued at net asset value	57	60
Level 3 | Cash equivalent securities | Commercial paper
Fair value of plan assets in qualified defined benefit pension plan		0
Level 3 | Equity securities | Mutual funds
Fair value of plan assets in qualified defined benefit pension plan	0
Level 3 | Equity securities | Common stock
Fair value of plan assets in qualified defined benefit pension plan	0	0
Level 3 | Debt securities | U.S. Treasury and other U.S. government agency securities
Fair value of plan assets in qualified defined benefit pension plan	0	0
Level 3 | Debt securities | Corporate and municipal bonds and notes
Fair value of plan assets in qualified defined benefit pension plan	0	0
Level 3 | Debt securities | Collateralized mortgage obligations
Fair value of plan assets in qualified defined benefit pension plan	0	0
Level 3 | Private placements
Fair value of plan assets in qualified defined benefit pension plan	$ 57	$ 60

Employee Benefit Plans (Summary

Employee Benefit Plans (Summary of Changes in the Corporation's Qualified Defined Benefit Pension Plan's Level 3 Investments Measured at Fair Value on a Recurring Basis) (Details) - Private placements - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Balance at beginning of period	$ 60	$ 80
Gains (Losses) Realized	3	(1)
Gains (Losses) Unrealized	8	(7)
Purchases	49	70
Sales	(63)	(82)
Balance at end of period	$ 57	$ 60

Employee Benefit Plans (Sched_2

Employee Benefit Plans (Schedule of Estimated Future Employer Contributions) (Details) $ in Millions	Dec. 31, 2019USD ($)
Qualified Plan
2019	$ 134
2020	133
2021	136
2022	137
2023	139
2024 - 2028	683
Non-Qualified Plan
2019	14
2020	14
2021	14
2022	15
2023	15
2024 - 2028	74
Postretirement Benefit Plan
2019	5	[1]
2020	5	[1]
2021	5	[1]
2022	5	[1]
2023	4	[1]
2024 - 2028	$ 16	[1]
[1]	Estimated benefit payments in the postretirement benefit plan are net of estimated Medicare subsidies.

Income Taxes And Tax-Related _3

Income Taxes And Tax-Related Items Income Taxes And Tax-Related Items (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Deferred Tax Liability, net unrealized gains on investment securities available-for-sale	$ (20)				$ 0				$ (20)	$ 0
Deferred Tax Liability, Hedging gains and losses	(10)				0				(10)	0
Deferred Tax Assets, Operating Lease Liability	77				0				77	0
Income before income taxes									1,532	1,535	$ 1,234
Foreign-source income									42
Reductionindeferredtaxadjustment										99
Remeasurement of the Corporation's deferred tax balance									0	8	(107)
Tax benefits from employee stock transactions recorded in income statement									(12)	(23)	(35)
Provision for income taxes	82	$ 80	$ 87	$ 85	90	$ 63	$ 54	$ 93	334	300	$ 491
Liability for tax-related interest and penalties	8				7				8	7
Reasonably possible change in unrecognized tax benefits in next 12 months	5								5
Unrecognized tax benefits that would impact the effective tax rate	14				11				14	11
State net operating loss carryforwards	3				4				3	4
Deferred tax asset valuation allowance	$ 3				$ 3				$ 3	$ 3
Minimum
Years state net operating loss carryforwards expire									Dec. 31, 2019
Maximum
Years state net operating loss carryforwards expire									Dec. 31, 2028

Income Taxes And Tax-Related _4

Income Taxes And Tax-Related Items Current and Deferred Components of the Provision for Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Document Period End Date									Dec. 31, 2019
Current federal income tax									$ 267	$ 227	$ 371
Current foreign income tax									7	10	5
Current state and local income tax									48	39	36
Total current income tax									322	276	412
Deferred federal income tax									16	29	(26)
Deferred state and local income tax									(4)	3	(2)
Remeasurement of deferred taxes									0	(8)	107
Total deferred income tax									12	24	79
Provision for income taxes	$ 82	$ 80	$ 87	$ 85	$ 90	$ 63	$ 54	$ 93	$ 334	$ 300	$ 491

Income Taxes And Tax-Related _5

Income Taxes And Tax-Related Items Reconciliation of Expected Income Tax Expense at the Federal Statutory Rate to the Corporation's Provision for Income Taxes (Details) - USD ($) $ in Millions		3 Months Ended								12 Months Ended
		Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Document Period End Date										Dec. 31, 2019
Tax based on federal statutory rate, amount										$ 322	$ 323	$ 432
Tax based on federal statutory rate, percent										21.00%	21.00%	35.00%
State income tax, amount										$ 33	$ 35	$ 22
State income tax, percent										2.20%	2.30%	1.80%
Employee Stock Transactions, amount										$ 12	$ 23	$ 35
Employee Stock Transactions, percent										(0.80%)	(1.50%)	(2.80%)
Capitalization and recovery positions, amount	[1]									$ 0	$ (17)	$ 0
Capitalization and recovery positions, percent	[1]									0.00%	(1.10%)	0.00%
Affordable housing and historic credits, amount										$ (11)	$ (12)	$ (21)
Affordable housing and historic credits, percent										(0.70%)	(0.80%)	(1.70%)
Bank-owned life insurance, amount										$ (9)	$ (9)	$ (16)
Bank-owned life insurance, percent										(0.60%)	(0.60%)	(1.30%)
Remeasurement of the Corporation's deferred tax balance										$ 0	$ 8	$ (107)
Remearsurement of deferred taxes, percent										0.00%	0.50%	(8.70%)
FDIC fees, amount	[2]									$ 5	$ 8	$ 0
FDIC fees, percent	[2]									0.30%	0.50%	0.00%
Other changes in unrecognized tax benefits, amount										$ 0	$ 4	$ 0
Other changes in unrecognized tax benefits, percent										0.00%	0.30%	0.00%
Tax-related interest and penalties, amount										$ 2	$ (3)	$ 4
Tax-related interest and penalties, percent										0.10%	(0.20%)	0.30%
Lease termination transactions, amount										$ 0	$ 0	$ (2)
Lease termination transactions, percent										0.00%	0.00%	(0.20%)
Other, amount										$ 4	$ 2	$ 0
Other, percent										0.20%	0.10%	0.00%
Provision for income taxes, amount		$ 82	$ 80	$ 87	$ 85	$ 90	$ 63	$ 54	$ 93	$ 334	$ 300	$ 491
Provision for income taxes, percent										21.70%	19.50%	39.80%
[1]	Tax benefits from the review of tax capitalization and recovery positions related to software and fixed assets included in the 2017 tax return.
[2]	Beginning January 1, 2018, FDIC insurance expense is no longer deductible as a result of the enactment of the Tax Cuts and Jobs Act.

Income Taxes And Tax-Related _6

Income Taxes And Tax-Related Items Reconciliation of the Beginning and Ending Amounts of Unrecognized Tax Benefits (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Document Period End Date	Dec. 31, 2019
Balance at January 1	$ 14	$ 10	$ 15
Increases as a result of tax positions taken during a prior period	4	9	4
Decrease related to settlements with tax authorities	(1)	(4)	(8)
Decrease related to other tax position changes	0	(1)	(1)
Balance at December 31	$ 17	$ 14	$ 10

Income Taxes And Tax-Related _7

Income Taxes And Tax-Related Items Tax Years for Significant Jurisdictions That Remain Subject to Examination (Details)	12 Months Ended
	Dec. 31, 2019
Federal | Minimum
Open Tax Year	2014
Federal | Maximum
Open Tax Year	2018
California | Minimum
Open Tax Year	2006
California | Maximum
Open Tax Year	2017

Income Taxes And Tax-Related _8

Income Taxes And Tax-Related Items Principal Components of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Deferred Tax Assets, Operating Lease Liability	$ 77	$ 0
Document Period End Date	Dec. 31, 2019
Deferred tax assets:
Allowance for loan losses	$ 134	141
Deferred compensation	61	68
Deferred loan origination fees and costs	8	9
Net unrealized losses on investment securities available-for-sale	0	42
Other temporary differences, net	49	42
Total deferred tax asset before valuation allowance	329	302
Valuation allowance	(3)	(3)
Total deferred tax assets	326	299
Deferred tax liabilities:
Lease financing transactions	(73)	(74)
Deferred Tax Liability, net unrealized gains on investment securities available-for-sale	(20)	0
Defined benefit plans	(91)	(41)
Allowance for depreciation	(21)	(18)
Deferred Tax Liability, Hedging gains and losses	(10)	0
Leasing right of use asset	(69)	0
Total deferred tax liabilities	(284)	(133)
Net deferred tax asset	$ 42	$ 166

Transactions with Related Par_2

Transactions with Related Parties Transactions with Related Parties (Narrative) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2019USD ($)
Related Party Transactions [Abstract]
Loans attributed to persons who were related parties at beginning of period	$ 109
New loans to related parties	732
Repayments on loans to related parties	767
Loans attributed to persons who were related parties at end of period	$ 74

Regulatory Capital and Reserv_3

Regulatory Capital and Reserve Requirements Regulatory Capital and Reserve Requirements (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Federal Reserve Bank average reserve requirement	$ 586	$ 599
Dividends available to be paid to parent company without obtaining prior approval from bank regulatory agencies	98
Dividends from bank subsidiaries	$ 1,200	$ 1,100	$ 907
Total risk-based capital minimum to be well capitalized	10.00%	10.00%
Tier 1 risk-based capital minimum to be well capitalized	6.00%	6.00%
U.S. Banking Subsidiaries
Total risk-based capital minimum to be well capitalized	10.00%
Tier 1 risk-based capital minimum to be well capitalized	8.00%
Common equity tier 1 risk-based capital minimum to be well capitalized	6.50%
Leverage ratio minimum to be well capitalized	5.00%

Regulatory Capital and Reserv_4

Regulatory Capital and Reserve Requirements Regulatory Capital and Reserve Requirements (Summary of Capital Position) (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Comerica Incorporated
Summary of Capital Position [Line Items]
CET 1 capital	$ 6,919	$ 7,470
Tier 1 capital	6,919	7,470
Total capital	8,282	8,855
Risk-weighted assets	68,273	67,047
Average assets (fourth quarter)	$ 72,773	$ 71,070
CET 1 capital to risk-weighted assets	10.13%	11.14%
Tier 1 capital to risk-weighted assets	10.13%	11.14%
Total capital to risk-weighted assets	12.13%	13.21%
Tier 1 capital to average assets	9.51%	10.51%
Capital conservation buffer	4.13%	5.14%
CET 1 capital - minimum (Consolidated)	$ 3,100	$ 3,000
Tier 1 capital - minimum (Consolidated)	4,100	4,000
Total capital - minimum (Consolidated)	$ 5,500	$ 5,400
CET 1 capital to risk-weighted assets - minimum	4.50%	4.50%
Tier 1 capital to risk-weighted assets - minimum	6.00%	6.00%
Total capital to risk-weighted assets - minimum	8.00%	8.00%
Tier 1 capital to average assets - minimum	4.00%	4.00%
Comerica Bank
Summary of Capital Position [Line Items]
CET 1 capital	$ 7,199	$ 7,229
Tier 1 capital	7,199	7,229
Total capital	8,371	8,433
Risk-weighted assets	68,071	66,857
Average assets (fourth quarter)	$ 72,564	$ 70,905
CET 1 capital to risk-weighted assets	10.58%	10.81%
Tier 1 capital to risk-weighted assets	10.58%	10.81%
Total capital to risk-weighted assets	12.30%	12.61%
Tier 1 capital to average assets	9.92%	10.20%
Capital conservation buffer	4.30%	4.61%
CET 1 capital to risk-weighted assets - minimum	4.50%	4.50%
Tier 1 capital to risk-weighted assets - minimum	6.00%	6.00%
Total capital to risk-weighted assets - minimum	8.00%	8.00%
Tier 1 capital to average assets - minimum	4.00%	4.00%

Contingent Liabilities (Narrati

Contingent Liabilities (Narrative) (Details) - USD ($)	Jan. 17, 2014	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Loss Contingencies [Line Items]
Legal fees		$ 15,000,000	$ 17,000,000	$ 15,000,000
Pending Litigation | Minimum
Loss Contingencies [Line Items]
Loss contingency, estimate of possible loss		0
Pending Litigation | Maximum
Loss Contingencies [Line Items]
Loss contingency, estimate of possible loss		$ 45,000,000
Butte Local Development v. Masters Group v. Comerica Bank
Loss Contingencies [Line Items]
Amount of damages awarded by the jury	$ 52,000,000

Business Segment Information (N

Business Segment Information (Narrative) (Details)	12 Months Ended
	Dec. 31, 2019marketssegments
Segment Reporting [Abstract]
Number of Major Business Segments | segments	3
Number of Primary Market Segments | markets	3

Business Segment Information (B

Business Segment Information (Business Segment Financial Results) (Details) - USD ($) $ in Millions		3 Months Ended								12 Months Ended
		Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Dec. 31, 2019		Dec. 31, 2018		Dec. 31, 2017
Net interest income (expense)		$ 544	$ 586	$ 603	$ 606	$ 614	$ 599	$ 549	$ 590	$ 2,339		$ 2,352		$ 2,061
Provision for credit losses										74		(1)		74
Noninterest income										1,010		976		1,107
Noninterest expenses		451	435	424	433	448	452	446	448	1,743		1,794		1,860
Provision (benefit) for income taxes		(82)	(80)	(87)	(85)	(90)	(63)	(54)	(93)	(334)		(300)		(491)
Net income (loss)		$ 269	$ 292	$ 298	$ 339	$ 310	$ 318	$ 281	$ 326	1,198		1,235		743
Net loan charge-offs (recoveries)										107		51		92
Assets, average										71,488		70,724		71,452
Loans, average										50,511		48,766		48,558
Deposits, average										$ 55,481		$ 55,935		$ 57,258
Return on average assets	[1]									1.68%		1.75%		1.04%
Efficiency ratio	[2]									51.82%		53.56%		58.70%
Business Bank
Net interest income (expense)										$ 1,655		$ 1,613		$ 1,513
Provision for credit losses										88		6		69
Noninterest income										555		547		639
Noninterest expenses										795		847		918
Provision (benefit) for income taxes										(306)		(283)		(410)
Net income (loss)										1,021		1,024		755
Net loan charge-offs (recoveries)										111		52		96
Assets, average										44,946		43,207		42,653
Loans, average										43,472		41,618		41,241
Deposits, average										$ 29,047		$ 30,116		$ 31,999
Return on average assets	[1]									2.27%		2.37%		1.77%
Efficiency ratio	[2]									35.96%		39.22%		42.67%
Retail Bank
Net interest income (expense)										$ 568		$ 548		$ 453
Provision for credit losses										(4)		(1)		2
Noninterest income										132		136		154
Noninterest expenses										597		602		615
Provision (benefit) for income taxes										(24)		(18)		4
Net income (loss)										83		65		(6)
Net loan charge-offs (recoveries)										1		0		1
Assets, average										2,852		2,633		2,626
Loans, average										2,104		2,067		2,061
Deposits, average										$ 20,743		$ 20,812		$ 20,775
Return on average assets	[1]									0.39%		0.31%		(0.03%)
Efficiency ratio	[2]									84.49%		87.59%		101.29%
Wealth Management
Net interest income (expense)										$ 183		$ 181		$ 169
Provision for credit losses										(14)		(3)		1
Noninterest income										270		266		255
Noninterest expenses										283		293		285
Provision (benefit) for income taxes										(44)		(36)		(51)
Net income (loss)										140		121		87
Net loan charge-offs (recoveries)										(5)		(1)		(5)
Assets, average										5,083		5,214		5,401
Loans, average										4,935		5,081		5,256
Deposits, average										$ 3,833		$ 3,941		$ 4,081
Return on average assets	[1]									2.76%		2.32%		1.61%
Efficiency ratio	[2]									62.45%		65.60%		67.06%
Finance
Net interest income (expense)										$ (126)		$ (46)		$ (111)
Provision for credit losses										0		0		0
Noninterest income										43		27		49
Noninterest expenses										(1)		(4)		(4)
Provision (benefit) for income taxes										26		14		35
Net income (loss)										(56)		(1)		(23)
Net loan charge-offs (recoveries)										0		0		0
Assets, average										14,235		13,705		13,954
Loans, average										0		0		0
Deposits, average										1,673		941		241
Other
Net interest income (expense)										59		56		37
Provision for credit losses										4		(3)		2
Noninterest income										10		0		10
Noninterest expenses										69		56		46
Provision (benefit) for income taxes										14	[3]	23	[3]	(69)
Net income (loss)										10		26		(70)
Net loan charge-offs (recoveries)										0		0		0
Assets, average										4,372		5,965		6,818
Loans, average										0		0		0
Deposits, average										$ 185		$ 125		$ 162
[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.
[3]	Primarily reflected discrete tax items, including benefits of $17 million and $48 million in 2019 and 2018 , respectively, and a net charge of $72 million in 2017 .

Business Segment Information (M

Business Segment Information (Market Segment Financial Results) (Details) - USD ($) $ in Millions		3 Months Ended								12 Months Ended
		Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Dec. 31, 2019		Dec. 31, 2018		Dec. 31, 2017
Net interest income (expense)		$ 544	$ 586	$ 603	$ 606	$ 614	$ 599	$ 549	$ 590	$ 2,339		$ 2,352		$ 2,061
Provision for credit losses										74		(1)		74
Noninterest income										1,010		976		1,107
Noninterest expenses		451	435	424	433	448	452	446	448	1,743		1,794		1,860
Provision (benefit) for income taxes		(82)	(80)	(87)	(85)	(90)	(63)	(54)	(93)	(334)		(300)		(491)
Net income (loss)		$ 269	$ 292	$ 298	$ 339	$ 310	$ 318	$ 281	$ 326	1,198		1,235		743
Net loan charge-offs (recoveries)										107		51		92
Assets, average										71,488		70,724		71,452
Loans, average										50,511		48,766		48,558
Deposits, average										$ 55,481		$ 55,935		$ 57,258
Return on average assets	[1]									1.68%		1.75%		1.04%
Efficiency ratio	[2]									51.82%		53.56%		58.70%
Michigan
Net interest income (expense)										$ 729		$ 727		$ 657
Provision for credit losses										(11)		30		8
Noninterest income										291		296		324
Noninterest expenses										554		577		589
Provision (benefit) for income taxes										(108)		(90)		(137)
Net income (loss)										369		326		247
Net loan charge-offs (recoveries)										11		7
Assets, average										13,157		13,207		13,393
Loans, average										12,553		12,531		12,676
Deposits, average										$ 20,081		$ 20,770		$ 21,818
Return on average assets	[1]									1.77%		1.51%		1.09%
Efficiency ratio	[2]									54.02%		56.22%		60.01%
California
Net interest income (expense)										$ 811		$ 788		$ 711
Provision for credit losses										(33)		26		101
Noninterest income										173		164		171
Noninterest expenses										406		424		404
Provision (benefit) for income taxes										(155)		(123)		(145)
Net income (loss)										456		379		232
Net loan charge-offs (recoveries)										8		27
Assets, average										18,856		18,544		18,269
Loans, average										18,540		18,283		18,008
Deposits, average										$ 16,857		$ 16,964		$ 17,533
Return on average assets	[1]									2.42%		2.04%		1.25%
Efficiency ratio	[2]									41.21%		44.58%		45.83%
Texas
Net interest income (expense)										$ 493		$ 474		$ 451
Provision for credit losses										119		(53)		(72)
Noninterest income										128		130		131
Noninterest expenses										345		365		375
Provision (benefit) for income taxes										(38)		(64)		(104)
Net income (loss)										119		228		175
Net loan charge-offs (recoveries)										93		12
Assets, average										11,269		10,380		10,434
Loans, average										10,616		9,812		9,960
Deposits, average										$ 8,780		$ 8,992		$ 9,623
Return on average assets	[1]									1.06%		2.20%		1.61%
Efficiency ratio	[2]									55.59%		60.30%		64.35%
Other Markets
Net interest income (expense)										$ 373		$ 353		$ 316
Provision for credit losses										(5)		(1)		36
Noninterest income										365		359		423
Noninterest expenses										369		376		450
Provision (benefit) for income taxes										(74)		(60)		(71)
Net income (loss)										300		277		182
Net loan charge-offs (recoveries)										(5)		5
Assets, average										9,599		8,922		8,584
Loans, average										8,802		8,140		7,914
Deposits, average										$ 7,905		$ 8,144		$ 7,881
Return on average assets	[1]									3.13%		3.11%		2.12%
Efficiency ratio	[2]									50.03%		52.93%		60.98%
Finance & Other
Net interest income (expense)										$ (67)		$ 10		$ (74)
Provision for credit losses										4		(3)		1
Noninterest income										53		27		58
Noninterest expenses										69		52		42
Provision (benefit) for income taxes										41	[3]	37	[3]	(34)
Net income (loss)										(46)		25		(93)
Net loan charge-offs (recoveries)										0		0
Assets, average										18,607		19,671		20,772
Loans, average										0		0		0
Deposits, average										$ 1,858		$ 1,065		$ 403
[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.
[3]	Primarily reflected discrete tax items, including benefits of $17 million and $48 million in 2019 and 2018 , respectively, and a net charge of $72 million in 2017 .

Parent Company FInancial Stat_3

Parent Company FInancial Statements Parent Company Financial Statements (Balance Sheets) (Details) - USD ($) $ / shares in Units, $ in Millions	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Condensed Financial Statements, Captions [Line Items]
Cash and due from subsidiary bank	$ 973	$ 1,390
Other short-term investments	155	134
Premises and equipment	457	475
Accrued income and other assets	4,842	4,111
Total assets	73,402	70,818
Medium- and long-term debt	7,269	6,463
Other liabilities	1,440	1,243
Total liabilities	66,075	63,311
Common stock - $5 par value: Authorized - 325,000,000 shares; Issued - 228,164,824 shares	1,141	1,141
Capital surplus	2,174	2,148
Accumulated other comprehensive loss	(235)	(609)	$ (451)
Retained earnings	9,538	8,781
Less cost of common stock in treasury - 86,069,234 shares at 12/31/19 and 68,081,176 shares at 12/31/18	(5,291)	(3,954)
Total shareholders' equity	7,327	7,507	$ 7,963	$ 7,796
Total liabilities and shareholders' equity	$ 73,402	$ 70,818
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	86,069,234	68,081,176
Parent Company
Condensed Financial Statements, Captions [Line Items]
Cash and due from subsidiary bank	$ 1,196	$ 1,524
Other short-term investments	95	88
Investments in subsidiaries, principally banks	7,784	7,429
Premises and equipment	1	1
Accrued income and other assets	242	169
Total assets	9,318	9,211
Medium- and long-term debt	1,735	1,459
Other liabilities	256	245
Total liabilities	1,991	1,704
Common stock - $5 par value: Authorized - 325,000,000 shares; Issued - 228,164,824 shares	1,141	1,141
Capital surplus	2,174	2,148
Accumulated other comprehensive loss	(235)	(609)
Retained earnings	9,538	8,781
Less cost of common stock in treasury - 86,069,234 shares at 12/31/19 and 68,081,176 shares at 12/31/18	(5,291)	(3,954)
Total shareholders' equity	7,327	7,507
Total liabilities and shareholders' equity	$ 9,318	$ 9,211

Parent Company FInancial Stat_4

Parent Company FInancial Statements Parent Company Financial Statements (Statements of Income) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Dec. 31, 2019		Dec. 31, 2018		Dec. 31, 2017
Condensed Financial Statements, Captions [Line Items]
Other interest income									$ 71		$ 92		$ 60
Other noninterest income									109		96		108
Interest on medium- and long-term debt									197	[1]	144	[1]	76
Salaries and benefits expense									1,020		1,009		961
Occupancy expense									154		152		154
Equipment expense									50		48		45
Restructuring charges									0		53		45
Other noninterest expenses									81		80		84
Benefit for income taxes	$ 82	$ 80	$ 87	$ 85	$ 90	$ 63	$ 54	$ 93	334		300		491
Net Income	269	292	298	339	310	318	281	326	1,198		1,235		743
Less income allocated to participating securities	2	2	1	2	2	2	2	2	7		8		5
Net income attributable to common shares	$ 267	$ 290	$ 297	$ 337	$ 308	$ 316	$ 279	$ 324	1,191		1,227		738
Parent Company
Condensed Financial Statements, Captions [Line Items]
Dividends from subsidiaries									1,229		1,135		915
Other interest income									20		13		3
Intercompany management fee									224		228		136
Other noninterest income									0		0		8
Total income									1,473		1,376		1,062
Interest on medium- and long-term debt									56		29		13
Salaries and benefits expense									143		140		127
Occupancy expense									6		5		5
Equipment expense									1		1		1
Restructuring charges									0		2		6
Other noninterest expenses									72		75		80
Total expenses									278		252		232
Income before benefit for income taxes and equity in undistributed earnings of subsidiaries									1,195		1,124		830
Benefit for income taxes									(9)		(5)		(26)
Income before equity in undistributed earnings of subsidiaries									1,204		1,129		856
Equity in undistributed earnings of subsidiaries, principally banks									(6)		106		(113)
Net Income									1,198		1,235		743
Less income allocated to participating securities									7		8		5
Net income attributable to common shares									$ 1,191		$ 1,227		$ 738
[1]	Includes the effects of hedging.

Parent Company FInancial Stat_5

Parent Company FInancial Statements Parent Company Financial Statements (Statements of Cash Flows) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Condensed Financial Statements, Captions [Line Items]
Net income	$ 269	$ 292	$ 298	$ 339	$ 310	$ 318	$ 281	$ 326	$ 1,198	$ 1,235	$ 743
Depreciation and amortization									114	120	121
Net periodic defined benefit credit									(29)	(18)	(18)
Share-based compensation expense									39	48	39
Benefit for deferred income taxes									12	24	79
Other, net									(318)	184	39
Net cash provided by operating activities									1,090	1,616	1,085
Net change in premises and equipment									(86)	(90)	(69)
Net cash used in investing activities									(494)	(1,156)	(120)
Maturities of medium- and long-term debt									(350)	0	(500)
Repurchases of common stock									(1,394)	(1,338)	(560)
Cash dividends paid on common stock									(402)	(263)	(180)
Issuances of common stock under employee stock plans									18	52	118
Net cash provided by (used in) financing activities									661	(1,744)	(2,338)
Net (decrease) increase in cash and cash equivalents									1,257	(1,284)	(1,373)
Cash and cash equivalents at beginning of period				4,561			5,845		4,561	5,845	7,218
Cash and cash equivalents at end of period	5,818				4,561			5,845	5,818	4,561	5,845
Interest paid									462	261	122
Income taxes recovered									266	200	336
Parent Company
Condensed Financial Statements, Captions [Line Items]
Net income									1,198	1,235	743
Undistributed earnings of subsidiaries, principally banks									6	(106)	113
Depreciation and amortization									1	1	1
Net periodic defined benefit credit									4	4	(2)
Share-based compensation expense									15	21	16
Benefit for deferred income taxes									(2)	(1)	(10)
Other, net									28	10	59
Net cash provided by operating activities									1,250	1,164	920
Maturities of medium- and long-term debt									(350)	0	0
Repurchases of common stock									(1,394)	(1,338)	(560)
Cash dividends paid on common stock									(402)	(263)	(180)
Issuances of common stock under employee stock plans									18	52	118
Net cash provided by (used in) financing activities									(1,578)	(699)	(622)
Net (decrease) increase in cash and cash equivalents									(328)	465	298
Cash and cash equivalents at beginning of period				$ 1,524			$ 1,059		1,524	1,059	761
Cash and cash equivalents at end of period	$ 1,196				$ 1,524			$ 1,059	1,196	1,524	1,059
Interest paid									55	11	12
Income taxes recovered									$ (226)	$ (155)	$ (331)

Summary of Quarterly Financia_3

Summary of Quarterly Financial Statements (Unaudited) Summary of Quarterly Financial Statements (Unaudited) (Summary of Quarterly Financial Statements) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Quarterly Financial Information Disclosure [Abstract]
Interest income	$ 659	$ 711	$ 727	$ 710	$ 704	$ 675	$ 590	$ 650	$ 2,807	$ 2,619	$ 2,182
Interest expense	115	125	124	104	90	76	41	60	468	267	121
Net interest income	544	586	603	606	614	599	549	590	2,339	2,352	2,061
Provision for credit losses	8	35	44	(13)	16	0	12	(29)	74	(1)	74
Net securities losses	1	0	0	(8)	0	(20)	1	0	(7)	(19)	0
Noninterest income excluding net securities losses	265	256	250	246	250	254	243	248
Noninterest expenses	451	435	424	433	448	452	446	448	1,743	1,794	1,860
Provision for income taxes	82	80	87	85	90	63	54	93	334	300	491
Net Income	269	292	298	339	310	318	281	326	1,198	1,235	743
Less income allocated to participating securities	2	2	1	2	2	2	2	2	7	8	5
Net income attributable to common shares	$ 267	$ 290	$ 297	$ 337	$ 308	$ 316	$ 279	$ 324	$ 1,191	$ 1,227	$ 738
Basic earnings per common share	$ 1.87	$ 1.98	$ 1.95	$ 2.14	$ 1.91	$ 1.89	$ 1.62	$ 1.90	$ 7.95	$ 7.31	$ 4.23
Diluted earnings per common share	$ 1.85	$ 1.96	$ 1.94	$ 2.11	$ 1.88	$ 1.86	$ 1.59	$ 1.87	$ 7.87	$ 7.20	$ 4.14
Comprehensive income	$ 370	$ 338	$ 429	$ 435	$ 312	$ 296	$ 178	$ 290	$ 1,572	$ 1,076	$ 762

Revenue from Contracts with C_3

Revenue from Contracts with Customers Revenue from Contracts with Customers (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018		Dec. 31, 2017
Revenue from contracts with customers:
Total revenue from contracts with customers		$ 749	$ 755
Card fees		257	244		$ 333
Service charges on deposit accounts		203	211		227
Fiduciary income		206	206		198
Commercial lending fees		(91)	(85)		(85)
Letter of credit fees		38	40		45
Bank-owned life insurance		41	39		43
Foreign exchange income		44	47		45
Brokerage fees		28	27		23
Other sources of noninterest income		261	221		108
Total noninterest income		1,010	976		1,107
Adoption of Topic 606 change in presentation
Segment Reporting, Revenue Reconciling Item [Line Items]
Decrease in Card Fees Due To Presentation Change			140
Decrease in Service Charges on Deposit Accounts			5
Business Bank
Revenue from contracts with customers:
Total revenue from contracts with customers		369	365
Card fees					285
Service charges on deposit accounts					143
Fiduciary income					0
Commercial lending fees					(84)
Letter of credit fees					44
Bank-owned life insurance					0
Foreign exchange income					43
Brokerage fees					0
Other sources of noninterest income		186	182		40
Total noninterest income		555	547		639
Retail Bank
Revenue from contracts with customers:
Total revenue from contracts with customers		119	130
Card fees					43
Service charges on deposit accounts					79
Fiduciary income					0
Commercial lending fees					0
Letter of credit fees					0
Bank-owned life insurance					0
Foreign exchange income					0
Brokerage fees					0
Other sources of noninterest income		13	6		32
Total noninterest income		132	136		154
Wealth Management
Revenue from contracts with customers:
Total revenue from contracts with customers		261	259
Card fees					5
Service charges on deposit accounts					5
Fiduciary income					198
Commercial lending fees					(1)
Letter of credit fees					1
Bank-owned life insurance					0
Foreign exchange income					2
Brokerage fees					23
Other sources of noninterest income		9	7		20
Total noninterest income		270	266		255
Finance & Other
Revenue from contracts with customers:
Total revenue from contracts with customers		0	1
Card fees					0
Service charges on deposit accounts					0
Fiduciary income					0
Commercial lending fees					0
Letter of credit fees					0
Bank-owned life insurance					43
Foreign exchange income					0
Brokerage fees					0
Other sources of noninterest income		53	26		16
Total noninterest income		53	27		$ 59
Credit and Debit Card [Member]
Revenue from contracts with customers:
Total revenue from contracts with customers		257	244	[1]
Credit and Debit Card [Member] | Business Bank
Revenue from contracts with customers:
Total revenue from contracts with customers		213	201	[1]
Credit and Debit Card [Member] | Retail Bank
Revenue from contracts with customers:
Total revenue from contracts with customers		40	39	[1]
Credit and Debit Card [Member] | Wealth Management
Revenue from contracts with customers:
Total revenue from contracts with customers		4	4	[1]
Credit and Debit Card [Member] | Finance & Other
Revenue from contracts with customers:
Total revenue from contracts with customers		0	0	[1]
Service charges on deposit accounts
Revenue from contracts with customers:
Total revenue from contracts with customers		203	211	[1]
Service charges on deposit accounts | Business Bank
Revenue from contracts with customers:
Total revenue from contracts with customers		130	134	[1]
Service charges on deposit accounts | Retail Bank
Revenue from contracts with customers:
Total revenue from contracts with customers		68	72	[1]
Service charges on deposit accounts | Wealth Management
Revenue from contracts with customers:
Total revenue from contracts with customers		5	5	[1]
Service charges on deposit accounts | Finance & Other
Revenue from contracts with customers:
Total revenue from contracts with customers		0	0	[1]
Fiduciary income
Revenue from contracts with customers:
Total revenue from contracts with customers		206	206
Fiduciary income | Business Bank
Revenue from contracts with customers:
Total revenue from contracts with customers		0	0
Fiduciary income | Retail Bank
Revenue from contracts with customers:
Total revenue from contracts with customers		0	0
Fiduciary income | Wealth Management
Revenue from contracts with customers:
Total revenue from contracts with customers		206	206
Fiduciary income | Finance & Other
Revenue from contracts with customers:
Total revenue from contracts with customers		0	0
Commercial loan servicing fees
Revenue from contracts with customers:
Total revenue from contracts with customers	[2]	18	18
Commercial loan servicing fees | Business Bank
Revenue from contracts with customers:
Total revenue from contracts with customers	[2]	18	18
Commercial loan servicing fees | Retail Bank
Revenue from contracts with customers:
Total revenue from contracts with customers	[2]	0	0
Commercial loan servicing fees | Wealth Management
Revenue from contracts with customers:
Total revenue from contracts with customers	[2]	0	0
Commercial loan servicing fees | Finance & Other
Revenue from contracts with customers:
Total revenue from contracts with customers	[2]	0	0
Brokerage Commissions Revenue [Member]
Revenue from contracts with customers:
Total revenue from contracts with customers		28	27
Brokerage Commissions Revenue [Member] | Business Bank
Revenue from contracts with customers:
Total revenue from contracts with customers		0	0
Brokerage Commissions Revenue [Member] | Retail Bank
Revenue from contracts with customers:
Total revenue from contracts with customers		0	0
Brokerage Commissions Revenue [Member] | Wealth Management
Revenue from contracts with customers:
Total revenue from contracts with customers		28	27
Brokerage Commissions Revenue [Member] | Finance & Other
Revenue from contracts with customers:
Total revenue from contracts with customers		0	0
Other noninterest income
Revenue from contracts with customers:
Total revenue from contracts with customers	[3]	37	49
Other noninterest income | Business Bank
Revenue from contracts with customers:
Total revenue from contracts with customers	[3]	8	12
Other noninterest income | Retail Bank
Revenue from contracts with customers:
Total revenue from contracts with customers	[3]	11	19
Other noninterest income | Wealth Management
Revenue from contracts with customers:
Total revenue from contracts with customers	[3]	18	17
Other noninterest income | Finance & Other
Revenue from contracts with customers:
Total revenue from contracts with customers	[3]	$ 0	$ 1
[1]	Adoption of Topic 606 resulted in a change in presentation which records certain costs in the same category as the associated revenues. The effect of this change was to reduce card fees by $140 million and service charges on deposit accounts by $5 million for the twelve months ended December 31, 2018. Refer to Note 1 for further information.
[2]	Included in commercial lending fees on the Consolidated Statements of Income.
[3]	Excludes derivative, warrant and other miscellaneous income.

Leases (Narrative) (Details)

Leases (Narrative) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Leases [Abstract]
Lessee, Operating Lease, Term of Contract		9 years
Rental expense for leased properties and equipment		$ 81	$ 75	$ 78
Operating Lease, Expense		64
Variable Lease, Cost		19
Sublease Income		2
Right of use assets		$ 329
Lessee, Operating Lease, Discount Rate		3.78%
New Right of Use Assets		$ 49
Operating Lease, Payments		67
Sales-type Lease, Lease Income		14
Sales-type and Direct Financing Leases, Lease Receivable	[1]	$ 369
[1]	Excludes net investment in leveraged leases of $219 million .

Leases (Contractual Maturities

Leases (Contractual Maturities of Operating Lease Liabilities) (Details) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2019USD ($)
Leases [Abstract]
Lessee, Operating Lease, Liability, Payments, Remainder of Fiscal Year	$ 60
Lessee, Operating Lease, Liability, Payments, Due Year Two	62
Lessee, Operating Lease, Liability, Payments, Due Year Three	53
Lessee, Operating Lease, Liability, Payments, Due Year Four	46
Lessee, Operating Lease, Liability, Payments, Due Year Five	42
Lessee, Operating Lease, Liability, Payments, Due after Year Five	175
Lessee, Operating Lease, Liability, Payments, Due	438
Operating lease imputed interest	(71)
Operating lease liabilities	$ 367

Leases (Contractual Maturitie_2

Leases (Contractual Maturities of Sales-Type and Direct Financing Lease Receivables) (Details) (Details) $ in Millions	Dec. 31, 2019USD ($)
Leases [Abstract]
Sales-type and Direct Financing Leases, Lease Receivable, Payments to be Received, Remainder of Fiscal Year	$ 66
Sales-type and Direct Financing Leases, Lease Receivable, Payments to be Received, Two Years	54
Sales-type and Direct Financing Leases, Lease Receivable, Payments to be Received, Three Years	90
Sales-type and Direct Financing Leases, Lease Receivable, Payments to be Received, Four Years	45
Sales-type and Direct Financing Leases, Lease Receivable, Payments to be Received, Five Years	40
Sales-type and Direct Financing Leases, Lease Receivable, Payments to be Received, Thereafter	31
Sales-type and Direct Financing Leases, Lease Receivable, Payments to be Received	326
Sales- Type and Direct Financing Leases, Unguaranteed Residual Asset	64
Deferred Discounts, Finance Charges and Interest Included in Receivables	(21)
Sales-type and Direct Financing Leases, Lease Receivable	$ 369	[1]
[1]	Excludes net investment in leveraged leases of $219 million .