Comerica (CMA) 10-Q30 Apr 182018 Q1 Quarterly reportFinancial data

Company Profile

Document And Entity Information

Document And Entity Information - shares	3 Months Ended
Document And Entity Information - shares	Mar. 31, 2018	Apr. 24, 2018
Document And Entity Information [Abstract]
Document Type	10-Q
Document Period End Date	Mar. 31, 2018
Amendment Flag	false
Entity Registrant Name	Comerica INC /NEW/
Entity Central Index Key	28,412
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q1
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		171,933,253
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
ASSETS
Cash and due from banks	$ 1,173	$ 1,438
Interest-bearing deposits with banks	5,663	4,407
Other short-term investments	133	96
Investment securities available-for-sale	11,971	10,938	[1]
Investment securities held-to-maturity	0	1,266
Commercial loans	30,909	31,060
Real estate construction loans	3,114	2,961
Commercial mortgage loans	9,272	9,159
Lease financing	464	468
International loans	964	983
Residential mortgage loans	2,003	1,988
Consumer loans	2,514	2,554
Total loans	49,240	49,173
Less allowance for loan losses	(698)	(712)
Net loans	48,542	48,461
Premises and equipment	468	466
Accrued income and other assets	4,385	4,495
Total assets	72,335	71,567
LIABILITIES AND SHAREHOLDERS' EQUITY
Noninterest-bearing deposits	30,961	32,071
Money market and interest-bearing checking deposits	22,355	21,500
Savings deposits	2,233	2,152
Customer certificates of deposit	2,071	2,165
Foreign office time deposits	15	15
Total interest-bearing deposits	26,674	25,832
Total deposits	57,635	57,903
Short-term borrowings	48	10
Accrued expenses and other liabilities	1,058	1,069
Medium- and long-term debt	5,594	4,622
Total liabilities	64,335	63,604
Common stock - $5 par value: Authorized - 325,000,000 shares; Issued - 228,164,824 shares	1,141	1,141
Capital surplus	2,134	2,122
Accumulated other comprehensive loss	(553)	(451)
Retained earnings	8,110	7,887
Less cost of common stock in treasury - 53,835,135 shares at 9/30/17 and 52,851,156 shares at 12/31/16	(2,832)	(2,736)
Total shareholders' equity	8,000	7,963
Total liabilities and shareholders' equity	$ 72,335	$ 71,567

[1]	Included auction-rate securities at amortized cost and fair value of $51 million and $49 million, respectively, as of December 31, 2017.

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Mar. 31, 2018	Dec. 31, 2017
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	55,690,402	55,306,483

Consolidated Statements Of Comp

Consolidated Statements Of Comprehensive Income - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2018		Mar. 31, 2017
INTEREST INCOME
Interest and fees on loans		$ 509		$ 421
Interest on investment securities		64		61
Interest on short-term investments		17		14
Total interest income		590		496
INTEREST EXPENSE
Interest on deposits		16		9
Interest on medium- and long-term debt	[1]	25		17
Total interest expense		41		26
Net interest income		549		470
Provision for credit losses		12		16
Net interest income after provision for credit losses		537		454
NONINTEREST INCOME
Card fees		59	[2]	77
Service charges on deposit accounts		54	[2]	58
Fiduciary income		52		49
Commercial lending fees		18		20
Letter of credit fees		10		12
Bank-owned life insurance		9		10
Foreign exchange income		12		11
Brokerage fees		7		5
Other noninterest income		23		29
Total noninterest income		244		271
NONINTEREST EXPENSES
Salaries and benefits expense		255		245
Outside processing fee expense		61		87
Net occupancy expense		38		38
Equipment expense		11		11
Restructuring charges		16		11
Software expense		31		29
FDIC insurance expense		13		13
Advertising expense		6		4
Litigation-related expense		0		(2)
Other noninterest expenses		15		21
Total noninterest expenses		446		457
Income before income taxes		335		268
Provision for income taxes		54		66
Net Income		281		202
Less income allocated to participating securities		2		2
Net income attributable to common shares		$ 279		$ 200
Basic earnings per common share		$ 1.62		$ 1.15
Diluted earnings per common share		$ 1.59		$ 1.11
Comprehensive income		$ 178		$ 206
Cash dividends declared on common stock		$ 52		$ 42
Cash dividends declared per common share		$ 0.30		$ 0.23

[1]	Includes the effects of hedging.
[2]	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 $34 million and service charges on deposit accounts by $1 million for the first quarter 2018. Refer to note 1 for further information.

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 (Cumulative effect of change in accounting principle)	$ 1		$ 3		$ (2)
BALANCE at Dec. 31, 2016	7,796	$ 1,141	2,135	$ (383)	7,331	$ (2,428)
BALANCE (in shares) at Dec. 31, 2016		175.3
Net income	202				202
Other comprehensive income, net of tax	4			4
Cash dividends declared on common stock	(42)				(42)
Purchase of common stock	(118)					(118)
Purchase of common stock (in shares)		(1.7)
Net issuance of common stock under employee stock plans	69		(25)		(14)	108
Net issuance of common stock under employee stock plans (in shares)		2.3
Net issuance of common stock for warrants	0		(24)		(44)	68
Net issuance of common stock for warrants (in shares)		1.5
Share-based compensation	18		18
Other	0		(1)			1
Other (in shares)		0
BALANCE at Mar. 31, 2017	7,930	$ 1,141	2,106	(379)	7,431	(2,369)
BALANCE (in shares) at Mar. 31, 2017		177.4
BALANCE (Cumulative effect of change in accounting principle)	15			1	14
BALANCE at Dec. 31, 2017	7,963	$ 1,141	2,122	(451)	7,887	(2,736)
BALANCE (in shares) at Dec. 31, 2017		172.9
Net income	281				281
Other comprehensive income, net of tax	(103)			(103)
Cash dividends declared on common stock	(52)				(52)
Purchase of common stock	(159)					(159)
Purchase of common stock (in shares)		(1.7)
Net issuance of common stock under employee stock plans	31		(11)		(17)	59
Net issuance of common stock under employee stock plans (in shares)		1.2
Net issuance of common stock for warrants	0		(1)		(3)	4
Net issuance of common stock for warrants (in shares)		0.1
Share-based compensation	24		24
BALANCE at Mar. 31, 2018	$ 8,000	$ 1,141	$ 2,134	$ (553)	$ 8,110	$ (2,832)
BALANCE (in shares) at Mar. 31, 2018		172.5

Consolidated Statements Of Cha6

Consolidated Statements Of Changes In Shareholders' Equity (Parenthetical) - $ / shares	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Statement of Stockholders' Equity [Abstract]
Cash dividends declared on common stock, per share	$ 0.30	$ 0.23

Consolidated Statements Of Cash

Consolidated Statements Of Cash Flows - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
OPERATING ACTIVITIES
Net income	$ 281	$ 202
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for credit losses	12	16
Provision (benefit) for deferred income taxes	7	(1)
Depreciation and amortization	31	31
Net periodic defined benefit credit	(5)	(4)
Share-based compensation expense	24	18
Net amortization of securities	1	2
Net change in accrued income receivable	(26)	3
Net change in accrued expenses payable	(22)	5
Other, net	55	132
Net cash provided by operating activities	358	404
INVESTING ACTIVITIES
Maturities and redemptions of investment securities available-for-sale	444	393
Sales of investment securities available-for-sale	5	1,259
Purchases of investment securities available-for-sale	(441)	(1,699)
Maturities and redemptions of investment securities held-to-maturity	0	76
Net change in loans	(98)	752
Proceeds from sales of foreclosed property	1	3
Net increase in premises and equipment	(20)	(12)
Purchases of Federal Home Loan Bank stock	(41)	0
Proceeds from settlement of BOLI policies	3	3
Other, net	0	1
Net cash (used in) provided by investing activities	(147)	776
FINANCING ACTIVITIES
Net change in deposits	(77)	(5)
Net change in short-term borrowings	38	16
Issuances of medium- and long-term debt	1,000	0
Repurchases of common stock	(168)	(126)
Cash dividends paid on common stock	(53)	(40)
Issuances of common stock under employee stock plans	40	77
Other, net	0	(1)
Net cash provided by (used in) financing activities	780	(79)
Net increase in cash and cash equivalents	991	1,101
Cash and cash equivalents at beginning of period	5,845	7,218
Cash and cash equivalents at end of period	6,836	8,319
Interest paid	40	27
Income tax paid (refunds received)	2	(1)
Noncash investing and financing activities:
Loans transferred to other real estate	1	1
Securities transferred from held-to-maturity to available-for-sale	(1,266)	0
Securities transferred from available-for-sale to equity securities	$ 81	$ 0

Basis of Presentation and Accou

Basis of Presentation and Accounting Policies	3 Months Ended
Basis of Presentation and Accounting Policies	Mar. 31, 2018
Accounting Policies [Abstract]
Basis of Presentation and Accounting Policies	BASIS OF PRESENTATION AND ACCOUNTING POLICIES Organization The accompanying unaudited consolidated financial statements were prepared in accordance with United States (U.S.) generally accepted accounting principles (GAAP) for interim financial information and with the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, the statements do not include all of the information and footnotes required by GAAP for complete financial statements. In the opinion of management, all adjustments (consisting of normal recurring accruals) considered necessary for a fair presentation were included. The results of operations for the three months ended March 31, 2018 are not necessarily indicative of the results that may be expected for the year ending December 31, 2018 . Certain items in prior periods were reclassified to conform to the current presentation. For further information, refer to the consolidated financial statements and footnotes thereto included in the Annual Report of Comerica Incorporated and Subsidiaries (the Corporation) on Form 10-K for the year ended December 31, 2017 . Revenue Recognition Effective January 1, 2018, the Corporation adopted the provision of Financial Accounting Standards Board (FASB) Accounting Standards Codification (ASC) Topic 606, "Revenue from Contracts with Customers" (Topic 606), using the modified retrospective method applied to all open contracts as of January 1, 2018. Under Topic 606, card fee revenue from certain products is generally presented net of network costs, including interchange costs, surcharge fees and assessment fees, as opposed to the previous presentation of associated network costs in outside processing fees in the Consolidated Statements of Comprehensive Income. Similar adjustments were made for other revenue streams that resulted in certain costs being recognized in the same category as the associated revenues in noninterest income. The impact on the Consolidated Statements of Comprehensive Income of adopting Topic 606 was a $34 million decrease in card fees and a $1 million decrease in service charges on deposit accounts included in noninterest income, along with a corresponding $35 million decrease in outside processing fees included in noninterest expenses for the three months ended March 31, 2018. The Corporation previously deferred recognition of certain treasury management fees included in service charges on deposit accounts in the Consolidated Statements of Comprehensive Income until the amount of compensation was considered fixed and determinable. Under the new guidance, the portion of these fees that are based on agreed upon rates less estimated credits expected to be earned by the customer is recognized as services are rendered. As a result, the Corporation recorded a transition adjustment of $14 million , after tax, to retained earnings, included in cumulative effect of change in accounting principles in the accompanying Consolidated Statements of Changes in Shareholders Equity. Similar adjustments were made for other revenue streams that resulted in an additional cumulative transition after-tax adjustment to retained earnings of $2 million . The Corporation's revenues from contracts with customers may be recognized when services are complete 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 evenly 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 timing between completion of performance obligations and payment is typically not significant. Card fees comprise interchange and other fee income earned on government card, commercial card, debit/ATM 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. Network costs were approximately $34 million and $25 million for the three months ended March 31, 2018 and 2017, respectively. 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 prices and customer demand for services. Service charges on deposit accounts primarily comprise charges on retail and business accounts, including fees for treasury management services. These 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 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 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 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 are commissions earned for facilitating securities transactions for customers, as well other brokerage services provided. Revenue is recognized when services are complete and are 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 in the Consolidated Statements of Comprehensive Income. 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. Classification and Measurement of Financial Instruments Effective January 1, 2018, the Corporation adopted the provisions of Accounting Standards Update (ASU) No. 2016-01, "Financial Instruments - Overall (Subtopic 825-10): Recognition of Financial Assets and Financial Liabilities," (ASU 2016-01). ASU 2016-01 requires equity investments, other than equity method investments, to be measured at fair value with changes in fair value recognized in net income. At adoption, an immaterial amount of cumulative net unrealized losses on equity securities previously recognized in accumulated other comprehensive income (AOCI) was reclassified to the opening balance of retained earnings, included in cumulative effect of change in accounting principles in the accompanying Consolidated Statements of Changes in Shareholders Equity. Changes to the fair value of equity securities occurring after December 31, 2017, other than equity method investments, are included in net securities losses in the Consolidated Statements of Comprehensive Income. Also, as part of adopting ASU 2016-01, the Corporation refined the calculation used to determine the estimated fair value of loans disclosed in note 2 to the consolidated financial statements. Statement of Cash Flows The Corporation adopted FASB issued ASU No. 2016-15, “Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments,” (ASU 2016-15) on January 1, 2018 and, as a result, reclassified $3 million of proceeds from settlement of bank-owned life insurance policies from operating activities to investing activities for the three-month period ended March 31, 2017. Defined Benefit Pension and Other Postretirement Costs The Corporation retrospectively adopted the provisions of ASU No. 2017-07, “Compensation - Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost” (ASU 2017-07) on January 1, 2018, which requires employers to report service cost as part of compensation expense and the other components of net benefit cost separately from service cost. As a result, $12 million of benefit from the other components of net benefit cost was reclassified from salaries and benefits expense to other noninterest expenses in the Consolidated Statements of Comprehensive Income for the three months ended March 31, 2017. The Corporation based the adjustment to the prior period on amounts disclosed in note 10. Derivatives Instruments and Hedging Activities The Corporation adopted ASU No. 2017-12, “Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities” (ASU 2017-12), effective January 1, 2018. At transition, the Corporation elected to change the measurement methodology of all long-haul fair value hedges existing at December 31, 2017. The prior period effect of this election was a $1 million reduction to opening retained earnings, included in cumulative effect of change in accounting principles in the Consolidated Statements of Shareholders' Equity. In addition, the Corporation made a transition election to reclassify the portfolio of held-to-maturity securities to available-for-sale in January 2018 as the securities are eligible to be hedged. This resulted in the recognition of additional unrealized losses of $11 million at the date of transfer. Income Taxes 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. Also on December 22, 2017, the Securities and Exchange Commission issued Staff Accounting Bulletin No. 118 (SAB 118), which provides guidance on accounting for tax effects of the Act. SAB 118 provides a measurement period of up to one year from the enactment date to complete the accounting. Based on the information available and current interpretation of the rules, the Corporation has made reasonable estimates of the impact of the reduction in the corporate tax rate and remeasurement of certain deferred tax assets and liabilities based on the rate at which they are expected to reverse in the future, generally 21 percent. The provisional amount recorded related to the remeasurement of the Corporation's deferred tax balance was $104 million , including $107 million recognized in the year ended December 31, 2017 and a $3 million downward revision to the estimated impact recorded in the three months ended March 31, 2018. The final impact of the Act may differ from these estimates as a result of changes in management’s interpretations and assumptions, as well as new guidance that may be issued by the Internal Revenue Service (IRS).

Fair Value Measurements

Fair Value Measurements	3 Months Ended
Fair Value Measurements	Mar. 31, 2018
Fair Value Disclosures [Abstract]
Fair Value Measurements	FAIR VALUE MEASUREMENTS The Corporation utilizes fair value measurements to record fair value adjustments to certain assets and liabilities and to determine fair value disclosures. The determination of fair values of financial instruments often requires the use of estimates. In cases where quoted market values in an active market are not available, the Corporation uses present value techniques and other valuation methods to estimate the fair values of its financial instruments. These valuation methods require considerable judgment and the resulting estimates of fair value can be significantly affected by the assumptions made and methods used. Equity securities, investment securities available-for-sale, derivatives and deferred compensation plan assets and liabilities 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. Refer to note 1 to the consolidated financial statements in the Corporation's Annual Report on Form 10-K for the year ended December 31, 2017 for further information about the fair value hierarchy, descriptions of the valuation methodologies and key inputs used to measure financial assets and liabilities recorded at fair value, as well as a description of the methods and significant assumptions used to estimate fair value disclosures for financial instruments not recorded at fair value in their entirety on a recurring basis. ASSETS AND LIABILITIES RECORDED AT FAIR VALUE ON A RECURRING BASIS The following tables present the recorded amount of assets and liabilities measured at fair value on a recurring basis as of March 31, 2018 and December 31, 2017 . (in millions) Total Level 1 Level 2 Level 3 March 31, 2018 Deferred compensation plan assets $ 93 $ 93 $ — $ — Equity securities 38 38 — — Investment securities available-for-sale: U.S. Treasury and other U.S. government agency securities 2,706 2,706 — — Residential mortgage-backed securities (a) 9,265 — 9,265 — Total investment securities available-for-sale 11,971 2,706 9,265 — Derivative assets: Interest rate contracts 33 — 26 7 Energy derivative contracts 107 — 107 — Foreign exchange contracts 37 — 37 — Warrants 2 — — 2 Total derivative assets 179 — 170 9 Total assets at fair value $ 12,281 $ 2,837 $ 9,435 $ 9 Derivative liabilities: Interest rate contracts $ 98 $ — $ 98 $ — Energy derivative contracts 106 — 106 — Foreign exchange contracts 32 — 32 — Total derivative liabilities 236 — 236 — Deferred compensation plan liabilities 93 93 — — Total liabilities at fair value $ 329 $ 93 $ 236 $ — (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, 2017 Trading securities: Deferred compensation plan assets $ 92 $ 92 $ — $ — Investment securities available-for-sale: U.S. Treasury and other U.S. government agency securities 2,727 2,727 — — Residential mortgage-backed securities (a) 8,124 — 8,124 — State and municipal securities 5 — — 5 (b) Equity and other non-debt securities 82 38 — 44 (b) Total investment securities available-for-sale 10,938 2,765 8,124 49 Derivative assets: Interest rate contracts 57 — 43 14 Energy derivative contracts 93 — 93 — Foreign exchange contracts 42 — 42 — Warrants 2 — — 2 Total derivative assets 194 — 178 16 Total assets at fair value $ 11,224 $ 2,857 $ 8,302 $ 65 Derivative liabilities: Interest rate contracts $ 59 $ — $ 59 $ — Energy derivative contracts 91 — 91 — Foreign exchange contracts 40 — 40 — Total derivative liabilities 190 — 190 — Deferred compensation plan liabilities 92 92 — — Total liabilities at fair value $ 282 $ 92 $ 190 $ — (a) Issued and/or guaranteed by U.S. government agencies or U.S. government-sponsored enterprises. (b) Auction-rate securities. 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 each of the three-month period ended March 31, 2018 and 2017 . The following table summarizes the changes in Level 3 assets and liabilities measured at fair value on a recurring basis for the three-month period ended March 31, 2018 and 2017 . Net Realized/Unrealized Gains (Losses) (Pretax) Recorded in Earnings Balance at Beginning of Period Balance at End of Period Change in Classification (a) Sales and Redemptions (in millions) Realized Unrealized Three Months Ended March 31, 2018 Equity securities — 44 — — — (44 ) — Investment securities available-for-sale: State and municipal securities (b) $ 5 $ — $ — $ — $ (5 ) $ — Equity and other non-debt securities (b) 44 (44 ) — — — — Total investment securities available-for-sale 49 (44 ) — — (5 ) — Derivative assets: Interest rate contracts 14 — — (7 ) (c) — 7 Warrants 2 — — — — 2 Three Months Ended March 31, 2017 Investment securities available-for-sale: State and municipal securities (b) $ 7 $ — $ — $ — $ (2 ) $ 5 Equity and other non-debt securities (b) 47 — — — (1 ) 46 Total investment securities available-for-sale 54 — — — (3 ) 51 Derivative assets: Interest rate contracts 11 — — — — — 11 Warrants 3 — 1 (c) (1 ) (c) (1 ) 2 (a) Reflects the reclassification of equity securities resulting from the adoption of ASU 2016-01. (b) Auction-rate securities. (c) Realized and unrealized gains and losses due to changes in fair value recorded in Other Noninterest Income on the Consolidated Statements of Comprehensive Income. ASSESTS AND LIABILITIES AT FAIR VALUE ON A NONRECURRING BASIS The Corporation may be required to record certain assets and liabilities at fair value on a nonrecurring basis. These include assets that are recorded at the lower of cost or fair value, and were recognized at fair value since it was less than cost at the end of the period. The following table presents assets recorded at fair value on a nonrecurring basis at March 31, 2018 and December 31, 2017 . No liabilities were recorded at fair value on a nonrecurring basis at March 31, 2018 and December 31, 2017 . (in millions) Level 3 March 31, 2018 Loans: Commercial $ 102 Commercial mortgage 4 Total assets at fair value $ 106 December 31, 2017 Loans: Commercial $ 111 Commercial mortgage 5 Total assets at fair value $ 116 Level 3 assets recorded at fair value on a nonrecurring basis at March 31, 2018 and December 31, 2017 included loans 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 March 31, 2018 Assets Cash and due from banks $ 1,173 $ 1,173 $ 1,173 $ — $ — Interest-bearing deposits with banks 5,663 5,663 5,663 — — Loans held-for-sale 2 2 — 2 — Total loans, net of allowance for loan losses (a) 48,542 48,345 — — 48,345 Customers’ liability on acceptances outstanding 2 2 2 — — Restricted equity investments 248 248 248 — — Nonmarketable equity securities (b) 6 9 Liabilities Demand deposits (noninterest-bearing) 30,961 30,961 — 30,961 — Interest-bearing deposits 24,603 24,603 — 24,603 — Customer certificates of deposit 2,071 2,041 — 2,041 — Total deposits 57,635 57,605 — 57,605 — Short-term borrowings 48 48 48 — — Acceptances outstanding 2 2 2 — — Medium- and long-term debt 5,594 5,604 — 5,604 — Credit-related financial instruments (68 ) (68 ) — — (68 ) December 31, 2017 Assets Cash and due from banks $ 1,438 $ 1,438 $ 1,438 $ — $ — Interest-bearing deposits with banks 4,407 4,407 4,407 — — Investment securities held-to-maturity 1,266 1,246 — 1,246 — Loans held-for-sale 4 4 — 4 — Total loans, net of allowance for loan losses (a) 48,461 48,153 — — 48,153 Customers’ liability on acceptances outstanding 2 2 2 — — Restricted equity investments 207 207 207 — — Nonmarketable equity securities (b) 6 9 Liabilities Demand deposits (noninterest-bearing) 32,071 32,071 — 32,071 — Interest-bearing deposits 23,667 23,667 — 23,667 — Customer certificates of deposit 2,165 2,142 — 2,142 — Total deposits 57,903 57,880 — 57,880 — Short-term borrowings 10 10 10 — — Acceptances outstanding 2 2 2 — — Medium- and long-term debt 4,622 4,636 — 4,636 — Credit-related financial instruments (67 ) (67 ) — — (67 ) (a) Included $106 million and $116 million of impaired loans recorded at fair value on a nonrecurring basis at March 31, 2018 and December 31, 2017 , 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	3 Months Ended
Investment Securities	Mar. 31, 2018
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 March 31, 2018 Investment securities available-for-sale: U.S. Treasury and other U.S. government agency securities $ 2,744 $ — $ 38 $ 2,706 Residential mortgage-backed securities (a) 9,500 13 248 9,265 Total investment securities available-for-sale $ 12,244 $ 13 $ 286 $ 11,971 December 31, 2017 Investment securities available-for-sale: U.S. Treasury and other U.S. government agency securities $ 2,743 $ — $ 16 $ 2,727 Residential mortgage-backed securities (a) 8,230 22 128 8,124 State and municipal securities 5 — — 5 Equity and other non-debt securities 83 1 2 82 Total investment securities available-for-sale (b) $ 11,061 $ 23 $ 146 $ 10,938 Investment securities held-to-maturity (c): Residential mortgage-backed securities (a) $ 1,266 $ — $ 20 $ 1,246 (a) Issued and/or guaranteed by U.S. government agencies or U.S. government-sponsored enterprises. (b) Included auction-rate securities at amortized cost and fair value of $51 million and $49 million , respectively, as of December 31, 2017 . (c) The amortized cost of investment securities held-to-maturity included net unrealized losses of $9 million at December 31, 2017 related to securities transferred from available-for-sale in 2014, which are included in accumulated other comprehensive loss. In connection with the adoption of ASU 2016-01 on January 1, 2018, cumulative unrealized gains and losses on available-for-sale equity and other non-debt securities were reclassified to retained earnings and the carrying value was reclassified to other short-term investments. Additionally, the Corporation transferred residential mortgage-backed securities with a book value of approximately $1.3 billion from held-to-maturity to available-for-sale upon the adoption of ASU 2017-12. For additional information about the adoption of ASU 2016-01, refer to note 1. A summary of the Corporation’s investment securities in an unrealized loss position as of March 31, 2018 and December 31, 2017 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 March 31, 2018 U.S. Treasury and other U.S. government agency securities $ 2,706 $ 38 $ — $ — $ 2,706 $ 38 Residential mortgage-backed securities (a) 4,623 81 3,855 167 8,478 248 Total temporarily impaired securities $ 7,329 $ 119 $ 3,855 $ 167 $ 11,184 $ 286 December 31, 2017 U.S. Treasury and other U.S. government agency securities $ 2,727 $ 16 $ — $ — $ 2,727 $ 16 Residential mortgage-backed securities (a) 3,845 32 4,003 125 7,848 157 State and municipal securities (c) — — 5 — (b) 5 — (b) Equity and other non-debt securities (c) — — 44 2 44 2 Total temporarily impaired securities $ 6,572 $ 48 $ 4,052 $ 127 $ 10,624 $ 175 (a) Issued and/or guaranteed by U.S. government agencies or U.S. government-sponsored enterprises. (b) Unrealized losses less than $0.5 million. (c) Primarily auction-rate securities. At March 31, 2018 , the Corporation had 377 securities in an unrealized loss position with no credit impairment, including 29 U.S. Treasury securities and 348 residential mortgage-backed securities. 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 March 31, 2018 . There were no significant gains or losses of debt securities available-for-sale or equity securities during the three months ended March 31, 2018 , including the sale and redemption of the remaining auction-rate securities in the investment securities portfolio. Additionally, there were no significant gains or losses of investment securities available-for-sale during the three months ended March 31, 2017 . 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) March 31, 2018 Amortized Cost Fair Value Contractual maturity Within one year $ 100 $ 100 After one year through five years 2,861 2,823 After five years through ten years 1,727 1,709 After ten years 7,557 7,339 Total investment securities $ 12,245 $ 11,971 Included in the contractual maturity distribution in the table above were residential mortgage-backed securities with total amortized cost of $9.5 billion and fair value of $9.3 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 March 31, 2018 , investment securities with a carrying value of $628 million were pledged where permitted or required by law to secure $311 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	3 Months Ended
Credit Quality And Allowance For Credit Losses	Mar. 31, 2018
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 March 31, 2018 Business loans: Commercial $ 84 $ 29 $ 26 $ 139 $ 242 $ 30,528 $ 30,909 Real estate construction: Commercial Real Estate business line (a) 12 — — 12 — 2,746 2,758 Other business lines (b) — — — — — 356 356 Total real estate construction 12 — — 12 — 3,102 3,114 Commercial mortgage: Commercial Real Estate business line (a) 15 — — 15 9 1,882 1,906 Other business lines (b) 20 6 8 34 20 7,312 7,366 Total commercial mortgage 35 6 8 49 29 9,194 9,272 Lease financing — — — — 3 461 464 International 14 — — 14 4 946 964 Total business loans 145 35 34 214 278 44,231 44,723 Retail loans: Residential mortgage 11 1 — 12 29 1,962 2,003 Consumer: Home equity 6 2 1 9 19 1,735 1,763 Other consumer 1 — 1 2 — 749 751 Total consumer 7 2 2 11 19 2,484 2,514 Total retail loans 18 3 2 23 48 4,446 4,517 Total loans $ 163 $ 38 $ 36 $ 237 $ 326 $ 48,677 $ 49,240 December 31, 2017 Business loans: Commercial $ 79 $ 134 $ 12 $ 225 $ 309 $ 30,526 $ 31,060 Real estate construction: Commercial Real Estate business line (a) 3 — — 3 — 2,627 2,630 Other business lines (b) 4 — — 4 — 327 331 Total real estate construction 7 — — 7 — 2,954 2,961 Commercial mortgage: Commercial Real Estate business line (a) 14 — — 14 9 1,808 1,831 Other business lines (b) 27 6 22 55 22 7,251 7,328 Total commercial mortgage 41 6 22 69 31 9,059 9,159 Lease financing — — — — 4 464 468 International 13 — — 13 6 964 983 Total business loans 140 140 34 314 350 43,967 44,631 Retail loans: Residential mortgage 10 2 — 12 31 1,945 1,988 Consumer: Home equity 5 1 — 6 21 1,789 1,816 Other consumer 4 — 1 5 — 733 738 Total consumer 9 1 1 11 21 2,522 2,554 Total retail loans 19 3 1 23 52 4,467 4,542 Total loans $ 159 $ 143 $ 35 $ 337 $ 402 $ 48,434 $ 49,173 (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 March 31, 2018 Business loans: Commercial $ 29,195 $ 579 $ 893 $ 242 $ 30,909 Real estate construction: Commercial Real Estate business line (e) 2,758 — — — 2,758 Other business lines (f) 352 4 — — 356 Total real estate construction 3,110 4 — — 3,114 Commercial mortgage: Commercial Real Estate business line (e) 1,836 15 46 9 1,906 Other business lines (f) 7,144 107 95 20 7,366 Total commercial mortgage 8,980 122 141 29 9,272 Lease financing 453 5 3 3 464 International 926 5 29 4 964 Total business loans 42,664 715 1,066 278 44,723 Retail loans: Residential mortgage 1,973 1 — 29 2,003 Consumer: Home equity 1,733 — 11 19 1,763 Other consumer 750 1 — — 751 Total consumer 2,483 1 11 19 2,514 Total retail loans 4,456 2 11 48 4,517 Total loans $ 47,120 $ 717 $ 1,077 $ 326 $ 49,240 December 31, 2017 Business loans: Commercial $ 29,263 $ 591 $ 897 $ 309 $ 31,060 Real estate construction: Commercial Real Estate business line (e) 2,630 — — — 2,630 Other business lines (f) 327 4 — — 331 Total real estate construction 2,957 4 — — 2,961 Commercial mortgage: Commercial Real Estate business line (e) 1,759 20 43 9 1,831 Other business lines (f) 7,099 115 92 22 7,328 Total commercial mortgage 8,858 135 135 31 9,159 Lease financing 440 23 1 4 468 International 946 11 20 6 983 Total business loans 42,464 764 1,053 350 44,631 Retail loans: Residential mortgage 1,955 2 — 31 1,988 Consumer: Home equity 1,786 1 8 21 1,816 Other consumer 737 1 — — 738 Total consumer 2,523 2 8 21 2,554 Total retail loans 4,478 4 8 52 4,542 Total loans $ 46,942 $ 768 $ 1,061 $ 402 $ 49,173 (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 - on pages F-51 and F-52 in the Corporation's 2017 Annual Report. 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) March 31, 2018 December 31, 2017 Nonaccrual loans $ 326 $ 402 Reduced-rate loans (a) 8 8 Total nonperforming loans 334 410 Foreclosed property (b) 5 5 Total nonperforming assets $ 339 $ 415 (a) There were no reduced-rate business loans at both March 31, 2018 and December 31, 2017 . Reduced-rate retail loans were $8 million at both March 31, 2018 and December 31, 2017 . (b) Included $4 million of foreclosed residential real estate properties at both March 31, 2018 and December 31, 2017 . There were no retail loans secured by residential real estate properties in process of foreclosure included in nonaccrual loans at both March 31, 2018 and December 31, 2017 . Allowance for Credit Losses The following table details the changes in the allowance for loan losses and related loan amounts. 2018 2017 (in millions) Business Loans Retail Loans Total Business Loans Retail Loans Total Three Months Ended March 31 Allowance for loan losses: Balance at beginning of period $ 661 $ 51 $ 712 $ 682 $ 48 $ 730 Loan charge-offs (36 ) (1 ) (37 ) (42 ) (2 ) (44 ) Recoveries on loans previously charged-off 8 1 9 9 2 11 Net loan charge-offs (28 ) — (28 ) (33 ) — (33 ) Provision for loan losses 20 (6 ) 14 12 (1 ) 11 Balance at end of period $ 653 $ 45 $ 698 $ 661 $ 47 $ 708 As a percentage of total loans 1.46 % 0.99 % 1.42 % 1.51 % 1.05 % 1.47 % March 31 Allowance for loan losses: Individually evaluated for impairment $ 42 $ — $ 42 $ 87 $ 2 $ 89 Collectively evaluated for impairment 611 45 656 574 45 619 Total allowance for loan losses $ 653 $ 45 $ 698 $ 661 $ 47 $ 708 Loans: Individually evaluated for impairment $ 384 $ 31 $ 415 $ 535 $ 41 $ 576 Collectively evaluated for impairment 44,339 4,486 48,825 43,287 4,440 47,727 Total loans evaluated for impairment $ 44,723 $ 4,517 $ 49,240 $ 43,822 $ 4,481 $ 48,303 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. Three Months Ended March 31, (in millions) 2018 2017 Balance at beginning of period $ 42 $ 41 Provision for credit losses on lending-related commitments (2 ) 5 Balance at end of period $ 40 $ 46 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 March 31, 2018 Business loans: Commercial $ 159 $ 156 $ 315 $ 403 $ 39 Commercial mortgage: Commercial Real Estate business line (a) 39 1 40 49 — Other business lines (b) 3 22 25 29 3 Total commercial mortgage 42 23 65 78 3 International 3 1 4 9 — Total business loans 204 180 384 490 42 Retail loans: Residential mortgage 11 8 19 20 — Consumer: Home equity 11 — 11 13 — Other consumer 1 — 1 2 — Total consumer 12 — 12 15 — Total retail loans (c) 23 8 31 35 — Total individually evaluated impaired loans $ 227 $ 188 $ 415 $ 525 $ 42 December 31, 2017 Business loans: Commercial $ 105 $ 267 $ 372 $ 460 $ 63 Commercial mortgage: Commercial Real Estate business line (a) 39 1 40 49 — Other business lines (b) 3 22 25 29 3 Total commercial mortgage 42 23 65 78 3 International — 6 6 17 1 Total business loans 147 296 443 555 67 Retail loans: Residential mortgage 14 8 22 22 — Consumer: Home equity 11 — 11 14 — Other consumer 1 — 1 2 — Total consumer 12 — 12 16 — Total retail loans (c) 26 8 34 38 — Total individually evaluated impaired loans $ 173 $ 304 $ 477 $ 593 $ 67 (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 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 Three Months Ended March 31 Business loans: Commercial $ 344 $ 1 $ 498 $ 2 Commercial mortgage: Commercial Real Estate business line (a) 40 1 7 — Other business lines (b) 25 — 34 — Total commercial mortgage 65 1 41 — International 5 — 11 — Total business loans 414 2 550 2 Retail loans: Residential mortgage 20 — 27 — Consumer loans: Home equity 11 — 14 — Other consumer 1 — 4 — Total consumer 12 — 18 — Total retail loans 32 — 45 — Total individually evaluated impaired loans $ 446 $ 2 $ 595 $ 2 (a) Primarily loans to real estate developers. (b) Primarily loans secured by owner-occupied real estate. Troubled Debt Restructurings The following table details the recorded balance at March 31, 2018 and 2017 of loans considered to be troubled debt restructurings (TDRs) that were restructured during the three-month periods ended March 31, 2018 and 2017 , all of which were principal deferrals. Principal Deferrals (a) (in millions) 2018 2017 Three Months Ended March 31 Business loans: Commercial $ 28 $ 80 Commercial mortgage: Other business lines (b) 1 5 Total business loans 29 85 Retail loans: Consumer: Home equity (c) 1 1 Total loans $ 30 $ 86 (a) Primarily represents loan balances where terms were extended 90 days or more at or above contractual interest rates. (b) Primarily loans to 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. At March 31, 2018 and December 31, 2017 , commitments to lend additional funds to borrowers whose terms have been modified in TDRs totaled $21 million and $31 million , respectively. All of the modifications considered to be TDRs that occurred during the three months ended March 31, 2018 and 2017 were principal deferrals. The Corporation charges interest on principal balances outstanding during deferral periods. Additionally, none of the modifications involved forgiveness of principal. As a result, the current and future financial effects of the recorded balance of loans considered to be TDRs that were restructured during the three months ended March 31, 2018 and 2017 were insignificant. On an ongoing basis, the Corporation monitors the performance of modified loans to their restructured terms. The allowance for loan losses continues to be reassessed on the basis of an individual evaluation of the loan. The following table presents information regarding the recorded balance at March 31, 2018 and 2017 of loans modified by principal deferral during the twelve-month periods ended March 31, 2018 and 2017 . 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. There were no subsequent defaults of principal deferral loans during the three-month periods ended March 31, 2018 and 2017 . Principal Deferrals (in millions) 2018 2017 Balance at March 31, Business loans: Commercial $ 90 $ 141 Commercial mortgage: Commercial Real Estate business line (a) 37 — Other business lines (a) 2 9 Total commercial mortgage 39 9 Total business loans 129 150 Retail loans: Consumer: Home equity (b) 2 2 Total principal deferrals $ 131 $ 152 (a) Primarily loans secured by owner-occupied real estate. (b) Includes bankruptcy loans for which the court has discharged the borrower's obligation and the borrower has not reaffirmed the debt. During the twelve-month periods ended March 31, 2018 and 2017 , loans with a carrying value of $17 million and $1 million , respectively, were modified by interest rate reduction (reduced-rate loans), and loans with a carrying value of $20 million and $48 million , respectively, were restructured into two notes (AB note restructures). For reduced-rate loans and AB note restructures, a subsequent payment default is defined in terms of delinquency, when a principal or interest payment is 90 days past due. There were no subsequent payment defaults of reduced-rate loans or AB note restructures during the three-month periods ended March 31, 2018 and 2017 .

Derivative And Credit-Related F

Derivative And Credit-Related Financial Instruments	3 Months Ended
Derivative And Credit-Related Financial Instruments	Mar. 31, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative And Credit-Related Financial Instruments	DERIVATIVE AND CREDIT-RELATED FINANCIAL INSTRUMENTS In the normal course of business, the Corporation enters into various transactions involving derivative and credit-related financial instruments to manage exposure to fluctuations in interest rate, foreign currency and other market risks and to meet the financing needs of customers (customer-initiated derivatives). These financial instruments involve, to varying degrees, elements of market and credit risk. Market and credit risk are included in the determination of fair value. Market risk is the potential loss that may result from movements in interest rates, foreign currency exchange rates or energy commodity prices that cause an unfavorable change in the value of a financial instrument. The Corporation manages this risk by establishing monetary exposure limits and monitoring compliance with those limits. Market risk inherent in interest rate and energy contracts entered into on behalf of customers is mitigated by taking offsetting positions, except in those circumstances when the amount, tenor and/or contract rate level results in negligible economic risk, whereby the cost of purchasing an offsetting contract is not economically justifiable. The Corporation mitigates most of the inherent market risk in foreign exchange contracts entered into on behalf of customers by taking offsetting positions and manages the remainder through individual foreign currency position limits and aggregate value-at-risk limits. These limits are established annually and positions are monitored quarterly. Market risk inherent in derivative instruments held or issued for risk management purposes is typically offset by changes in the fair value of the assets or liabilities being hedged. Credit risk is the possible loss that may occur in the event of nonperformance by the counterparty to a financial instrument. The Corporation attempts to minimize credit risk arising from customer-initiated derivatives by evaluating the creditworthiness of each customer, adhering to the same credit approval process used for traditional lending activities and obtaining collateral as deemed necessary. Derivatives with dealer counterparties are either cleared through a clearinghouse or settled directly with a single counterparty. For derivatives settled directly with dealer counterparties, the Corporation utilizes counterparty risk limits and monitoring procedures as well as master netting arrangements and bilateral collateral agreements to facilitate the management of credit risk. Master netting arrangements effectively reduce credit risk by permitting settlement of positive and negative positions and offset cash collateral held with the same counterparty on a net basis. Bilateral collateral agreements require daily exchange of cash or highly rated securities issued by the U.S. Treasury or other U.S. government entities to collateralize amounts due to either party. At March 31, 2018 , counterparties with bilateral collateral agreements had pledged $5 million of marketable investment securities and deposited $8 million of cash with the Corporation to secure the fair value of contracts in an unrealized gain position, and the Corporation had pledged $11 million of marketable investment securities and posted $63 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 March 31, 2018 . 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 conducting hedging transactions 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 March 31, 2018 and December 31, 2017 . The table excludes commitments and warrants accounted for as derivatives. March 31, 2018 December 31, 2017 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 $ 1,775 $ — $ 3 $ 1,775 $ — $ 2 Derivatives used as economic hedges Foreign exchange contracts: Spot, forwards and swaps 647 — — 650 — 2 Total risk management purposes 2,422 — 3 2,425 — 4 Customer-initiated and other activities Interest rate contracts: Caps and floors written 582 — 2 635 — — Caps and floors purchased 582 2 — 635 — — Swaps 12,454 31 93 13,119 57 57 Total interest rate contracts 13,618 33 95 14,389 57 57 Energy contracts: Caps and floors written 135 — 11 164 — 11 Caps and floors purchased 135 11 — 164 11 — Swaps 1,755 96 95 1,519 82 80 Total energy contracts 2,025 107 106 1,847 93 91 Foreign exchange contracts: Spot, forwards, options and swaps 1,976 37 32 1,884 42 38 Total customer-initiated and other activities 17,619 177 233 18,120 192 186 Total gross derivatives $ 20,041 $ 177 $ 236 $ 20,545 $ 192 $ 190 Amounts offset in the Consolidated Balance Sheets: Netting adjustment - Offsetting derivative assets/liabilities (49 ) (49 ) (49 ) (49 ) Netting adjustment - Cash collateral received/posted (5 ) (62 ) (1 ) (39 ) Net derivatives included in the Consolidated Balance Sheets (b) 123 125 142 102 Amounts not offset in the Consolidated Balance Sheets: Marketable securities pledged under bilateral collateral agreements (5 ) (11 ) (3 ) (24 ) Net derivatives after deducting amounts not offset in the Consolidated Balance Sheets $ 118 $ 114 $ 139 $ 78 (a) Notional or contractual amounts, which represent the extent of involvement in the derivatives market, are used to determine the contractual cash flows required in accordance with the terms of the agreement. These amounts are typically not exchanged, significantly exceed amounts subject to credit or market risk and are not reflected in the Consolidated Balance Sheets. (b) Net derivative assets are included in accrued income and other assets and net derivative liabilities are included in accrued expenses and other liabilities on the Consolidated Balance Sheets. Included in the fair value of net derivative assets and net derivative liabilities are credit valuation adjustments reflecting counterparty credit risk and credit risk of the Corporation. The fair value of net derivative assets included credit valuation adjustments for counterparty credit risk of $3 million and $4 million at March 31, 2018 and December 31, 2017 , respectively. Risk Management The Corporation's derivative instruments used for managing interest rate risk currently comprise swaps converting fixed-rate long-term debt to variable rates. The following table details the effects of fair value hedging on the Consolidated Statements of Comprehensive Income. Interest on Medium- and Long-Term Debt Three Months Ended March 31, (in millions) 2018 2017 Total interest on medium-and long-term debt (a) $ 25 $ 17 Fair value hedging relationships: Interest rate contracts: Hedged items 15 22 Derivatives designated as hedging instruments (3 ) (10 ) (a) Includes the effects of hedging. 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 March 31, 2018 and December 31, 2017 . Weighted Average (dollar amounts in millions) Derivative Notional Amount Carrying Value of Hedged Items (a) Remaining Maturity (in years) Receive Rate Pay Rate (b) March 31, 2018 Swaps - fair value - receive fixed/pay floating rate Medium- and long-term debt $ 1,775 $ 1,794 4.4 3.26 % 2.59 % December 31, 2017 Swaps - fair value - receive fixed/pay floating rate Medium- and long-term debt 1,775 1,822 4.6 3.26 2.35 (a) Included $ 27 million and $ 56 million of cumulative hedging adjustments at March 31, 2018 and December 31, 2017 , respectively, which included $ 8 million and $ 9 million , respectively, of hedging adjustment on a discontinued hedging relationship. (b) Variable rates paid on receive fixed swaps are based on six-month LIBOR rates in effect at March 31, 2018 and December 31, 2017 . Foreign exchange rate risk arises from changes in the value of certain assets and liabilities denominated in foreign currencies. The Corporation employs spot and forward contracts in addition to swap contracts to manage exposure to these and other risks. These instruments are used as economic hedges and net gains or losses are included in other noninterest income in the Consolidated Statements of Comprehensive Income. Customer-Initiated and Other The Corporation enters into derivative transactions at the request of customers and generally takes offsetting positions with dealer counterparties to mitigate the inherent market risk. Income primarily results from the spread between the customer derivative and the offsetting dealer position. For customer-initiated foreign exchange contracts where offsetting positions have not been taken, the Corporation manages the remaining inherent market risk through individual foreign currency position limits and aggregate value-at-risk limits. These limits are established annually and reviewed quarterly. For those customer-initiated derivative contracts which were not offset or where the Corporation holds a position within the limits described above, the Corporation recognized no net gains or losses in other noninterest income in the Consolidated Statements of Comprehensive Income for both the three-month periods ended March 31, 2018 and 2017 . Fair values of customer-initiated and other derivative instruments represent the net unrealized gains or losses on such contracts and are recorded in the Consolidated Balance Sheets. Changes in fair value are recognized in the Consolidated Statements of Comprehensive Income. The net gains recognized in income on customer-initiated derivative instruments, net of the impact of offsetting positions, were as follows . Three Months Ended March 31, (in millions) Location of Gain 2018 2017 Interest rate contracts Other noninterest income $ 4 $ 6 Foreign exchange contracts Foreign exchange income 12 11 Total $ 16 $ 17 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) March 31, 2018 December 31, 2017 Unused commitments to extend credit: Commercial and other $ 22,169 $ 22,636 Bankcard, revolving check credit and home equity loan commitments 2,838 2,833 Total unused commitments to extend credit $ 25,007 $ 25,469 Standby letters of credit $ 3,245 $ 3,228 Commercial letters of credit 37 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 was $40 million and $42 million at March 31, 2018 and December 31, 2017 , 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 $26 million and $27 million at March 31, 2018 and December 31, 2017 , 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 $123 million and $127 million , respectively, of the $3.3 billion standby and commercial letters of credit outstanding at both March 31, 2018 and December 31, 2017 . The carrying value of the Corporation’s standby and commercial letters of credit, included in accrued expenses and other liabilities, totaled $42 million at March 31, 2018 , including $28 million in deferred fees and $14 million in the allowance for credit losses on lending-related commitments. At December 31, 2017 , the comparable amounts were $40 million , $25 million and $15 million , respectively. The following table presents a summary of criticized standby and commercial letters of credit at March 31, 2018 and December 31, 2017 . The Corporation's criticized list is generally consistent with the Special Mention, Substandard and Doubtful categories defined by regulatory authorities. The Corporation manages credit risk through underwriting, periodically reviewing and approving its credit exposures using Board committee approved credit policies and guidelines. (dollar amounts in millions) March 31, 2018 December 31, 2017 Total criticized standby and commercial letters of credit $ 77 $ 88 As a percentage of total outstanding standby and commercial letters of credit 2.4 % 2.7 % 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 March 31, 2018 and December 31, 2017 , the total notional amount of the credit risk participation agreements was approximately $540 million and $549 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 insignificant at March 31, 2018 and December 31, 2017 . 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 March 31, 2018 , the weighted average remaining maturity of outstanding credit risk participation agreements was 2.4 years.

Variable Interest Entities (VIE

Variable Interest Entities (VIEs)	3 Months Ended
Variable Interest Entities (VIEs)	Mar. 31, 2018
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. Exposure to loss as a result of the Corporation’s involvement with LIHTC entities at March 31, 2018 was limited to approximately $426 million . 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 other tax credit entities at March 31, 2018 was limited to approximately $7 million . 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 ( $165 million at March 31, 2018 ). Amortization and other write-downs of LIHTC investments are presented on a net basis as a component of the provision for income taxes on the Consolidated Statements of Comprehensive Income, while amortization and write-downs of other tax credit investments are recorded in other noninterest income. The income tax credits and deductions are recorded as a reduction of income tax expense and a reduction of federal income taxes payable. The Corporation provided no financial or other support that was not contractually required to any of the above VIEs during the three months ended March 31, 2018 and 2017 . The following table summarizes the impact of these tax credit entities on line items on the Corporation’s Consolidated Statements of Comprehensive Income. Three Months Ended March 31, (in millions) 2018 2017 Other noninterest income: Amortization of other tax credit investments $ 1 $ 1 Provision for income taxes: Amortization of LIHTC investments 15 16 Low income housing tax credits (15 ) (15 ) Other tax benefits related to tax credit entities (3 ) (6 ) Total provision for income taxes $ (3 ) $ (5 ) For further information on the Corporation’s consolidation policy, see note 1 to the consolidated financial statements in the Corporation's 2017 Annual Report.

Medium- And Long-Term Debt

Medium- And Long-Term Debt	3 Months Ended
Medium- And Long-Term Debt	Mar. 31, 2018
Debt Disclosure [Abstract]
Medium- And Long-Term Debt	MEDIUM- AND LONG-TERM DEBT Medium- and long-term debt is summarized as follows: (in millions) March 31, 2018 December 31, 2017 Parent company Subordinated notes: 3.80% subordinated notes due 2026 (a) $ 248 $ 255 Medium-term notes: 2.125% notes due 2019 (a) 346 347 Total parent company 594 602 Subsidiaries Subordinated notes: 4.00% subordinated notes due 2025 (a) 339 347 7.875% subordinated notes due 2026 (a) 201 208 Total subordinated notes 540 555 Medium-term notes: 2.50% notes due 2020 (a) 660 665 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 — Total FHLB advances 3,800 2,800 Total subsidiaries 5,000 4,020 Total medium- and long-term debt $ 5,594 $ 4,622 (a) The fixed interest rates on these notes have been swapped to a variable rate and designated in a hedging relationship. Accordingly, carrying value has been adjusted to reflect the change in the fair value of the debt as a result of changes in the benchmark rate. Subordinated notes with remaining maturities greater than one year qualify as Tier 2 capital. Comerica Bank (the Bank), a wholly-owned subsidiary of the Corporation, is a member of the FHLB, which provides short- and long-term funding to its members through advances collateralized by real estate-related assets. On February 7, 2018 , the Bank borrowed an additional $1.0 billion of 10-year, floating-rate FHLB advances due January 26, 2028 . The interest rate on the FHLB advances resets between four and eight weeks, based on the FHLB auction rate. At March 31, 2018 , the weighted-average rate on the FHLB advances was 1.85% . Each note may be prepaid in full, without penalty, at each scheduled reset date. Borrowing capacity is contingent on the amount of collateral available to be pledged to the FHLB. At March 31, 2018 , $15.8 billion of real estate-related loans were pledged to the FHLB as blanket collateral for current and potential future borrowings of approximately $4.4 billion . Unamortized debt issuance costs deducted from the carrying amount of medium- and long-term debt totaled $5 million at both March 31, 2018 and December 31, 2017 .

Accumulated Other Comprehensive

Accumulated Other Comprehensive Loss	3 Months Ended
Accumulated Other Comprehensive Loss	Mar. 31, 2018
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Accumulated Other Comprehensive 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 three months ended March 31, 2018 and 2017 , including the amount of income tax expense (benefit) allocated to each component of other comprehensive income (loss). Three Months Ended March 31, (in millions) 2018 2017 Accumulated net unrealized losses on investment securities: Balance at beginning of period, net of tax $ (101 ) $ (33 ) Cumulative effect of change in accounting principle 1 — Net unrealized holding losses arising during the period (142 ) (2 ) Less: Benefit for income taxes (33 ) (1 ) Net unrealized holding losses arising during the period, net of tax (109 ) (1 ) Less: Reclassification adjustment for net losses realized as a yield adjustment included in net income, net of tax — (1 ) Change in net unrealized losses on investment securities, net of tax (109 ) — Balance at end of period, net of tax $ (209 ) $ (33 ) Accumulated defined benefit pension and other postretirement plans adjustment: Balance at beginning of period, net of tax $ (350 ) $ (350 ) Amortization of actuarial net loss 15 13 Amortization of prior service credit (7 ) (7 ) Amounts recognized in other noninterest expense 8 6 Less: Provision for income taxes 2 2 Change in defined benefit pension and other postretirement plans adjustment, net of tax 6 4 Balance at end of period, net of tax $ (344 ) $ (346 ) Total accumulated other comprehensive loss at end of period, net of tax $ (553 ) $ (379 )

Net Income Per Common Share

Net Income Per Common Share	3 Months Ended
Net Income Per Common Share	Mar. 31, 2018
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. Three Months Ended March 31, (in millions, except per share data) 2018 2017 Basic and diluted Net income $ 281 $ 202 Less: Income allocated to participating securities 2 2 Net income attributable to common shares $ 279 $ 200 Basic average common shares 172 175 Basic net income per common share $ 1.62 $ 1.15 Basic average common shares 172 175 Dilutive common stock equivalents: Net effect of the assumed exercise of stock options 2 3 Net effect of the assumed exercise of warrants 1 2 Diluted average common shares 175 180 Diluted net income per common share $ 1.59 $ 1.11 There were no anti-dilutive options for both the three-month periods ended March 31, 2018 and 2017 .

Employee Benefit Plans

Employee Benefit Plans	3 Months Ended
Employee Benefit Plans	Mar. 31, 2018
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Abstract]
Employee Benefit Plans	EMPLOYEE BENEFIT PLANS Service costs are included in salaries and benefits expense and other components of net benefit cost (credit) are included in other noninterest expenses on the Consolidated Statements of Comprehensive Income. For further information on the Corporation's employee benefit plans, refer to note 17 to the consolidated financial statements in the Corporation's 2017 Annual Report. The components of net periodic benefit cost (credit) for the Corporation's qualified pension plan, non-qualified pension plan and postretirement benefit plan are as follows. Qualified Defined Benefit Pension Plan Three Months Ended March 31, (in millions) 2018 2017 Service cost $ 7 $ 7 Other components of net benefit credit: Interest cost 19 20 Expected return on plan assets (41 ) (40 ) Amortization of prior service credit (5 ) (5 ) Amortization of net loss 13 11 Total other components of net benefit credit (14 ) (14 ) Net periodic defined benefit credit $ (7 ) $ (7 ) Non-Qualified Defined Benefit Pension Plan Three Months Ended March 31, (in millions) 2018 2017 Service cost $ — $ 1 Other components of net benefit cost: Interest cost 2 2 Amortization of prior service credit (2 ) (2 ) Amortization of net loss 2 2 Total other components of net benefit cost 2 2 Net periodic defined benefit cost $ 2 $ 3 Postretirement Benefit Plan Three Months Ended March 31, (in millions) 2018 2017 Other components of net benefit cost: Interest cost $ 1 $ 1 Expected return on plan assets (1 ) (1 ) Net periodic defined benefit cost $ — $ —

Income Taxes And Tax-Related It

Income Taxes And Tax-Related Items	3 Months Ended
Income Taxes And Tax-Related Items	Mar. 31, 2018
Income Tax Disclosure [Abstract]
Income Taxes and Tax-Related Items	INCOME TAXES AND TAX-RELATED ITEMS Net unrecognized tax benefits were $10 million at both March 31, 2018 and December 31, 2017 . The Corporation anticipates it is reasonably possible that final settlements with tax authorities will result in a decrease in net unrecognized tax benefits of $1 million within the next twelve months. The liability for tax-related interest and penalties included in accrued expenses and other liabilities was $10 million at both March 31, 2018 and December 31, 2017 . Net deferred tax assets were $165 million at March 31, 2018 , compared to $141 million at December 31, 2017 . The increase of $24 million in net deferred tax assets resulted primarily from an increase in deferred tax assets related to unrealized losses on investment securities available-for-sale. Included in deferred tax assets at both March 31, 2018 and December 31, 2017 were $4 million of state net operating loss carryforwards, which expire between 2018 and 2027 . 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 March 31, 2018 and December 31, 2017 . In the ordinary course of business, the Corporation enters into certain transactions that have tax consequences. From time to time, the Internal Revenue Service (IRS) or other tax jurisdictions may review and/or challenge specific interpretive tax positions taken by the Corporation with respect to those transactions. The Corporation believes its tax returns were filed based upon applicable statutes, regulations and case law in effect at the time of the transactions. The IRS or other tax jurisdictions, an administrative authority or a court, if presented with the transactions, could disagree with the Corporation’s interpretation of the tax law. Based on current knowledge and probability assessment of various potential outcomes, the Corporation believes the 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.

Contingent Liabilities

Contingent Liabilities	3 Months Ended
Contingent Liabilities	Mar. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Contingent Liabilities	CONTINGENT LIABILITIES Legal Proceedings As previously reported in the Corporation's Form 10-K for the year ended December 31, 2017 , 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 tried in January 2014, in the Montana Second District Judicial Court for Silver Bow County in Butte, Montana. On January 17, 2014 , a jury awarded Masters $52 million against the Bank. On July 1, 2015, after an appeal filed by the Corporation, the Montana Supreme Court reversed the judgment against the Corporation and remanded the case for a new trial with instructions that Michigan contract law should apply and dismissing all other claims. The case was retried in the same district court, without a jury, in January 2017, and the Corporation awaits a ruling. Management believes 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 $3 million and $5 million were included in other noninterest expenses for the three months ended March 31, 2018 and 2017 , respectively. For matters where a loss is not probable, the Corporation has not established legal reserves. The Corporation believes the estimate of the aggregate range of reasonably possible losses, in excess of reserves established, for all legal proceedings in which it is involved is from zero to approximately $28 million at March 31, 2018 . 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 an estimate can currently be made. The Corporation’s estimate involves significant judgment, given the varying stages of the proceedings (including the fact many are currently in preliminary stages), the existence in certain proceedings of multiple defendants (including the Corporation) whose share of liability has yet to be determined, the numerous yet-unresolved issues in many of the proceedings (including issues regarding class certification and the scope of many of the claims) and the attendant uncertainty of the various potential outcomes of such proceedings. Accordingly, the Corporation’s estimate will change from time to time, and actual losses may be more or less than the current estimate. In the event of unexpected future developments, it is possible the ultimate resolution of these matters, if unfavorable, may be material to the Corporation's consolidated financial condition, results of operations or cash flows. For information regarding income tax contingencies, refer to note 11 .

Restructuring Charges

Restructuring Charges	3 Months Ended
Restructuring Charges	Mar. 31, 2018
Restructuring and Related Activities [Abstract]
Restructuring Charges	RESTRUCTURING CHARGES The Corporation launched an initiative in 2016 designed to reduce overhead and increase revenue (the "GEAR Up" initiative). The actions in the initiative include, but are not limited to, a reduction in workforce, a new retirement program, streamlining operational processes, real estate optimization including consolidating banking centers as well as reducing office and operations space, selective outsourcing of technology functions, reduction of technology system applications, enhanced sales tools and training, expanded product offerings and improved customer analytics to drive opportunities. Certain actions associated with the GEAR Up initiative result in restructuring charges. Generally, costs associated with or incurred to generate revenue as part of the initiative are recorded according to the nature of the cost and are not included in restructuring charges. The Corporation considers the following costs associated with the initiative to be restructuring charges: • Employee costs: Primarily severance costs in accordance with the Corporation’s severance plan. • Facilities costs: Costs pertaining to consolidating banking centers and other facilities, such as lease termination costs and decommissioning costs. Also includes accelerated depreciation and impairment of owned property to be sold. • Technology costs: Impairment and other costs associated with optimizing technology infrastructure and reducing the number of applications. • Other costs: Includes primarily professional fees, as well as other contract termination fees and legal fees incurred in the execution of the initiative. Restructuring charges are recorded as a component of noninterest expenses on the Consolidated Statements of Comprehensive Income. The following table presents changes in restructuring reserves, cumulative charges incurred to date and total expected restructuring charges: (in millions) Employee Costs Facilities Costs Technology Costs Other Costs Total Three Months Ended March 31, 2018 Balance at beginning of period $ 8 $ — $ 6 $ 1 $ 15 Restructuring charges 5 1 10 — 16 Payments (3 ) (1 ) (7 ) (1 ) (12 ) Balance at end of period $ 10 $ — $ 9 $ — $ 19 Three Months Ended March 31, 2017 Balance at beginning of period $ 10 $ 4 $ — $ 4 $ 18 Restructuring charges 1 1 6 3 11 Payments (4 ) (5 ) — (4 ) (13 ) Adjustments for non-cash charges (a) — — (3 ) — (3 ) Balance at end of period $ 7 $ — $ 3 $ 3 $ 13 Total restructuring charges incurred to date $ 67 $ 18 $ 36 $ 33 $ 154 Total expected restructuring charges (b) 70 20 - 25 60 - 65 35 185 - 195 (a) Adjustments for non-cash charges primarily relate to impairments of previously capitalized software costs in Technology Costs. (b) Restructuring activities are expected to be substantially completed by 12/31/2018 . Restructuring charges directly attributable to a business segment are assigned to that business segment. Restructuring charges incurred by areas whose services support the overall Corporation are allocated based on the methodology described in note 22 to the consolidated financial statements in the Corporation's 2017 Annual Report. Total restructuring charges assigned to the Business Bank, Retail Bank and Wealth Management were $9 million , $5 million and $2 million , respectively, for the three months ended March 31, 2018 and $6 million , $4 million , and $1 million , respectively, for the three months ended March 31, 2017 . Remaining expected restructuring charges will be assigned to the business segments using the same methodology. Facilities costs pertaining to the consolidation of banking centers primarily impacted the Retail Bank.

Business Segment Information

Business Segment Information	3 Months Ended
Business Segment Information	Mar. 31, 2018
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 March 31, 2018 . The following discussion provides information about the activities of each business segment. A discussion of the financial results and the factors impacting performance can be found in the section entitled "Business Segments" in the financial review. The Business Bank meets the needs of 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 small business banking and personal financial services, consisting of consumer lending, consumer deposit gathering and mortgage loan origination. In addition to a full range of financial services provided to small business customers, this business segment offers a variety of consumer products, including deposit accounts, installment loans, credit cards, student loans, home equity lines of credit and residential mortgage loans. Wealth Management offers products and services consisting of fiduciary services, private banking, retirement services, investment management and advisory services, investment banking and brokerage services. This business segment also offers the sale of annuity products, as well as life, disability and long-term care insurance products. The Finance segment includes the Corporation’s securities portfolio and asset and liability management activities. This segment is responsible for managing the Corporation’s funding, liquidity and capital needs, performing interest sensitivity analysis and executing various strategies to manage the Corporation’s exposure to liquidity, interest rate risk and foreign exchange risk. The Other category includes the income and expense impact of equity and cash, tax benefits not assigned to specific business segments, charges of an unusual or infrequent nature that are not reflective of the normal operations of the business segments and miscellaneous other expenses of a corporate nature. For further information on the methodologies which form the basis for these results refer to note 23 to the consolidated financial statements in the Corporation's 2017 Annual Report. Business segment financial results are as follows: (dollar amounts in millions) Business Retail Wealth Management Finance Other Total Three Months Ended March 31, 2018 Earnings summary: Net interest income $ 330 $ 165 $ 41 $ 1 $ 12 $ 549 Provision for credit losses 10 4 (4 ) — 2 12 Noninterest income 121 42 68 11 2 244 Noninterest expenses 184 177 72 (1 ) 14 446 Provision (benefit) for income taxes 59 6 10 1 (22 ) (a) 54 Net income $ 198 $ 20 $ 31 $ 12 $ 20 $ 281 Net credit-related charge-offs (recoveries) $ 18 $ 12 $ (2 ) $ — $ — $ 28 Selected average balances: Assets $ 38,911 $ 6,427 $ 5,373 $ 13,779 $ 5,836 $ 70,326 Loans 37,368 5,807 5,246 — — 48,421 Deposits 27,314 24,064 3,796 823 93 56,090 Statistical data: Return on average assets (b) 2.07 % 0.33 % 2.30 % N/M N/M 1.62 % Efficiency ratio (c) 40.72 85.03 67.10 N/M N/M 56.33 (dollar amounts in millions) Business Retail Wealth Management Finance Other Total Three Months Ended March 31, 2017 Earnings summary: Net interest income (expense) $ 332 $ 160 $ 41 $ (71 ) $ 8 $ 470 Provision for credit losses 10 12 (1 ) — (5 ) 16 Noninterest income 144 48 64 11 4 271 Noninterest expenses 197 179 70 (1 ) 12 457 Provision (benefit) for income taxes 92 6 13 (24 ) (21 ) (a) 66 Net income (loss) $ 177 $ 11 $ 23 $ (35 ) $ 26 $ 202 Net credit-related charge-offs (recoveries) $ 30 $ 5 $ (2 ) $ — $ — $ 33 Selected average balances: Assets $ 38,091 $ 6,525 $ 5,406 $ 13,944 $ 7,853 $ 71,819 Loans 36,754 5,895 5,251 — — 47,900 Deposits 29,648 23,795 3,978 142 216 57,779 Statistical data: Return on average assets (b) 1.89 % 0.18 % 1.71 % N/M N/M 1.14 % Efficiency ratio (c) 41.39 86.01 67.17 N/M N/M 61.71 (a) Included tax benefits from employee stock transactions of $19 million and $24 million for the three months ended March 31, 2018 and 2017, respectively. (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 securities gains (losses). 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 March 31, 2018 . 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 Finance Total Three Months Ended March 31, 2018 Earnings summary: Net interest income $ 169 $ 180 $ 109 $ 78 $ 13 $ 549 Provision for credit losses 33 (2 ) (13 ) (8 ) 2 12 Noninterest income 73 39 31 88 13 244 Noninterest expenses 144 106 92 91 13 446 Provision (benefit) for income taxes 16 30 14 15 (21 ) (a) 54 Net income $ 49 $ 85 $ 47 $ 68 $ 32 $ 281 Net credit-related charge-offs (recoveries) $ (1 ) $ 13 $ 5 $ 11 $ — $ 28 Selected average balances: Assets $ 13,395 $ 18,581 $ 10,373 $ 8,362 $ 19,615 $ 70,326 Loans 12,604 18,347 9,830 7,640 — 48,421 Deposits 21,227 17,091 9,188 7,668 916 56,090 Statistical data: Return on average assets (b) 0.88 % 1.86 % 1.85 % 3.32 % N/M 1.62 % Efficiency ratio (c) 59.61 48.39 65.63 54.97 N/M 56.33 (dollar amounts in millions) Michigan California Texas Other Finance Total Three Months Ended March 31, 2017 Earnings summary: Net interest income (expense) $ 170 $ 171 $ 113 $ 79 $ (63 ) $ 470 Provision for credit losses (2 ) 21 (9 ) 11 (5 ) 16 Noninterest income 83 41 32 100 15 271 Noninterest expenses 150 96 94 106 11 457 Provision (benefit) for income taxes 37 36 22 16 (45 ) (a) 66 Net income (loss) $ 68 $ 59 $ 38 $ 46 $ (9 ) $ 202 Net credit-related charge-offs (recoveries) $ (3 ) $ 10 $ 22 $ 4 $ — $ 33 Selected average balances: Assets $ 13,254 $ 17,958 $ 10,555 $ 8,255 $ 21,797 $ 71,819 Loans 12,586 17,680 10,111 7,523 — 47,900 Deposits 22,150 17,243 10,113 7,915 358 57,779 Statistical data: Return on average assets (b) 1.20 % 1.32 % 1.35 % 2.13 % N/M 1.14 % Efficiency ratio (c) 59.50 45.25 64.80 59.31 N/M 61.71 (a) Included tax benefits from employee stock transactions of $19 million and $24 million for the three months ended March 31, 2018 and 2017, respectively. (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 securities gains (losses). N/M – not meaningful

Revenue from Contracts with Cus

Revenue from Contracts with Customers Revenue from Contracts with Customers	3 Months Ended
	Mar. 31, 2018
Revenue from Contract with Customer [Abstract]
Revenue from Contracts with Customers	REVENUE FROM CONTRACTS WITH CUSTOMERS Revenue from contracts with customers comprises the noninterest income earned by the Corporation in exchange for services provided to customers. The following table presents the composition of revenue from contracts with customers, segregated from other sources of noninterest income, by business segment. Business Bank Retail Bank Wealth Management Finance & Other Total (in millions) Three Months Ended March 31, 2018 Revenue from contracts with customers: Card fees (a) $ 47 $ 11 $ 1 $ — $ 59 Service charges on deposit accounts (a) 30 23 1 — 54 Fiduciary income — — 52 — 52 Commercial loan servicing fees (b) 4 — — — 4 Brokerage fees — — 7 — 7 Other noninterest income (c) 3 5 4 — 12 Total revenue from contracts with customers 84 39 65 — 188 Other sources of noninterest income 37 3 3 13 56 Total noninterest income $ 121 $ 42 $ 68 $ 13 $ 244 Three Months Ended March 31, 2017 Revenue from contracts with customers: Card fees $ 64 $ 12 $ 1 $ — $ 77 Service charges on deposit accounts 32 25 1 — 58 Fiduciary income — — 49 — 49 Commercial loan servicing fees (b) 3 — — — 3 Brokerage fees — — 5 — 5 Other noninterest income (c) 4 8 5 — 17 Total revenue from contracts with customers 103 45 61 — 209 Other sources of noninterest income 41 3 3 15 62 Total noninterest income $ 144 $ 48 $ 64 $ 15 $ 271 (a) 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 $34 million and service charges on deposit accounts by $1 million for the first quarter 2018. Refer to note 1 for further information. (b) Included in commercial lending fees on the Consolidated Statements of Comprehensive Income. (c) Excludes derivative, warrant and other miscellaneous income. Adjustments to revenue during the three months ended March 31, 2018 for refunds or credits relating to prior periods are not significant. Revenue from contracts with customers did not generate significant contract assets and liabilities.

Basis of Presentation and Acc23

Basis of Presentation and Accounting Policies Basis of Presentation and Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2018
Accounting Policies [Abstract]
Revenue Recognition	Revenue Recognition Effective January 1, 2018, the Corporation adopted the provision of Financial Accounting Standards Board (FASB) Accounting Standards Codification (ASC) Topic 606, "Revenue from Contracts with Customers" (Topic 606), using the modified retrospective method applied to all open contracts as of January 1, 2018. Under Topic 606, card fee revenue from certain products is generally presented net of network costs, including interchange costs, surcharge fees and assessment fees, as opposed to the previous presentation of associated network costs in outside processing fees in the Consolidated Statements of Comprehensive Income. Similar adjustments were made for other revenue streams that resulted in certain costs being recognized in the same category as the associated revenues in noninterest income. The impact on the Consolidated Statements of Comprehensive Income of adopting Topic 606 was a $34 million decrease in card fees and a $1 million decrease in service charges on deposit accounts included in noninterest income, along with a corresponding $35 million decrease in outside processing fees included in noninterest expenses for the three months ended March 31, 2018. The Corporation previously deferred recognition of certain treasury management fees included in service charges on deposit accounts in the Consolidated Statements of Comprehensive Income until the amount of compensation was considered fixed and determinable. Under the new guidance, the portion of these fees that are based on agreed upon rates less estimated credits expected to be earned by the customer is recognized as services are rendered. As a result, the Corporation recorded a transition adjustment of $14 million , after tax, to retained earnings, included in cumulative effect of change in accounting principles in the accompanying Consolidated Statements of Changes in Shareholders Equity. Similar adjustments were made for other revenue streams that resulted in an additional cumulative transition after-tax adjustment to retained earnings of $2 million . The Corporation's revenues from contracts with customers may be recognized when services are complete 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 evenly 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 timing between completion of performance obligations and payment is typically not significant. Card fees comprise interchange and other fee income earned on government card, commercial card, debit/ATM 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. Network costs were approximately $34 million and $25 million for the three months ended March 31, 2018 and 2017, respectively. 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 prices and customer demand for services. Service charges on deposit accounts primarily comprise charges on retail and business accounts, including fees for treasury management services. These 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 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 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 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 are commissions earned for facilitating securities transactions for customers, as well other brokerage services provided. Revenue is recognized when services are complete and are 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 in the Consolidated Statements of Comprehensive Income. 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.
Classification and Measurement of Financial Instruments	Classification and Measurement of Financial Instruments Effective January 1, 2018, the Corporation adopted the provisions of Accounting Standards Update (ASU) No. 2016-01, "Financial Instruments - Overall (Subtopic 825-10): Recognition of Financial Assets and Financial Liabilities," (ASU 2016-01). ASU 2016-01 requires equity investments, other than equity method investments, to be measured at fair value with changes in fair value recognized in net income. At adoption, an immaterial amount of cumulative net unrealized losses on equity securities previously recognized in accumulated other comprehensive income (AOCI) was reclassified to the opening balance of retained earnings, included in cumulative effect of change in accounting principles in the accompanying Consolidated Statements of Changes in Shareholders Equity. Changes to the fair value of equity securities occurring after December 31, 2017, other than equity method investments, are included in net securities losses in the Consolidated Statements of Comprehensive Income. Also, as part of adopting ASU 2016-01, the Corporation refined the calculation used to determine the estimated fair value of loans disclosed in note 2 to the consolidated financial statements.
Statement of Cash Flows	Statement of Cash Flows The Corporation adopted FASB issued ASU No. 2016-15, “Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments,” (ASU 2016-15) on January 1, 2018 and, as a result, reclassified $3 million of proceeds from settlement of bank-owned life insurance policies from operating activities to investing activities for the three-month period ended March 31, 2017.
Defined Benefit Pension and Other Postretirement Costs	Defined Benefit Pension and Other Postretirement Costs The Corporation retrospectively adopted the provisions of ASU No. 2017-07, “Compensation - Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost” (ASU 2017-07) on January 1, 2018, which requires employers to report service cost as part of compensation expense and the other components of net benefit cost separately from service cost. As a result, $12 million of benefit from the other components of net benefit cost was reclassified from salaries and benefits expense to other noninterest expenses in the Consolidated Statements of Comprehensive Income for the three months ended March 31, 2017. The Corporation based the adjustment to the prior period on amounts disclosed in note 10.
Derivatives Instruments and Hedging Activities	Derivatives Instruments and Hedging Activities The Corporation adopted ASU No. 2017-12, “Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities” (ASU 2017-12), effective January 1, 2018. At transition, the Corporation elected to change the measurement methodology of all long-haul fair value hedges existing at December 31, 2017. The prior period effect of this election was a $1 million reduction to opening retained earnings, included in cumulative effect of change in accounting principles in the Consolidated Statements of Shareholders' Equity. In addition, the Corporation made a transition election to reclassify the portfolio of held-to-maturity securities to available-for-sale in January 2018 as the securities are eligible to be hedged. This resulted in the recognition of additional unrealized losses of $11 million at the date of transfer.
Income Taxes	Income Taxes 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. Also on December 22, 2017, the Securities and Exchange Commission issued Staff Accounting Bulletin No. 118 (SAB 118), which provides guidance on accounting for tax effects of the Act. SAB 118 provides a measurement period of up to one year from the enactment date to complete the accounting. Based on the information available and current interpretation of the rules, the Corporation has made reasonable estimates of the impact of the reduction in the corporate tax rate and remeasurement of certain deferred tax assets and liabilities based on the rate at which they are expected to reverse in the future, generally 21 percent. The provisional amount recorded related to the remeasurement of the Corporation's deferred tax balance was $104 million , including $107 million recognized in the year ended December 31, 2017 and a $3 million downward revision to the estimated impact recorded in the three months ended March 31, 2018. The final impact of the Act may differ from these estimates as a result of changes in management’s interpretations and assumptions, as well as new guidance that may be issued by the Internal Revenue Service (IRS).

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	3 Months Ended
Fair Value Measurements (Tables)	Mar. 31, 2018
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 March 31, 2018 and December 31, 2017 . (in millions) Total Level 1 Level 2 Level 3 March 31, 2018 Deferred compensation plan assets $ 93 $ 93 $ — $ — Equity securities 38 38 — — Investment securities available-for-sale: U.S. Treasury and other U.S. government agency securities 2,706 2,706 — — Residential mortgage-backed securities (a) 9,265 — 9,265 — Total investment securities available-for-sale 11,971 2,706 9,265 — Derivative assets: Interest rate contracts 33 — 26 7 Energy derivative contracts 107 — 107 — Foreign exchange contracts 37 — 37 — Warrants 2 — — 2 Total derivative assets 179 — 170 9 Total assets at fair value $ 12,281 $ 2,837 $ 9,435 $ 9 Derivative liabilities: Interest rate contracts $ 98 $ — $ 98 $ — Energy derivative contracts 106 — 106 — Foreign exchange contracts 32 — 32 — Total derivative liabilities 236 — 236 — Deferred compensation plan liabilities 93 93 — — Total liabilities at fair value $ 329 $ 93 $ 236 $ — (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, 2017 Trading securities: Deferred compensation plan assets $ 92 $ 92 $ — $ — Investment securities available-for-sale: U.S. Treasury and other U.S. government agency securities 2,727 2,727 — — Residential mortgage-backed securities (a) 8,124 — 8,124 — State and municipal securities 5 — — 5 (b) Equity and other non-debt securities 82 38 — 44 (b) Total investment securities available-for-sale 10,938 2,765 8,124 49 Derivative assets: Interest rate contracts 57 — 43 14 Energy derivative contracts 93 — 93 — Foreign exchange contracts 42 — 42 — Warrants 2 — — 2 Total derivative assets 194 — 178 16 Total assets at fair value $ 11,224 $ 2,857 $ 8,302 $ 65 Derivative liabilities: Interest rate contracts $ 59 $ — $ 59 $ — Energy derivative contracts 91 — 91 — Foreign exchange contracts 40 — 40 — Total derivative liabilities 190 — 190 — Deferred compensation plan liabilities 92 92 — — Total liabilities at fair value $ 282 $ 92 $ 190 $ — (a) Issued and/or guaranteed by U.S. government agencies or U.S. government-sponsored enterprises. (b) Auction-rate securities.
Changes In Level 3 Assets And Liabilities Measured At Fair Value On A Recurring Basis	The following table summarizes the changes in Level 3 assets and liabilities measured at fair value on a recurring basis for the three-month period ended March 31, 2018 and 2017 . Net Realized/Unrealized Gains (Losses) (Pretax) Recorded in Earnings Balance at Beginning of Period Balance at End of Period Change in Classification (a) Sales and Redemptions (in millions) Realized Unrealized Three Months Ended March 31, 2018 Equity securities — 44 — — — (44 ) — Investment securities available-for-sale: State and municipal securities (b) $ 5 $ — $ — $ — $ (5 ) $ — Equity and other non-debt securities (b) 44 (44 ) — — — — Total investment securities available-for-sale 49 (44 ) — — (5 ) — Derivative assets: Interest rate contracts 14 — — (7 ) (c) — 7 Warrants 2 — — — — 2 Three Months Ended March 31, 2017 Investment securities available-for-sale: State and municipal securities (b) $ 7 $ — $ — $ — $ (2 ) $ 5 Equity and other non-debt securities (b) 47 — — — (1 ) 46 Total investment securities available-for-sale 54 — — — (3 ) 51 Derivative assets: Interest rate contracts 11 — — — — — 11 Warrants 3 — 1 (c) (1 ) (c) (1 ) 2 (a) Reflects the reclassification of equity securities resulting from the adoption of ASU 2016-01. (b) Auction-rate securities. (c) Realized and unrealized gains and losses due to changes in fair value recorded in Other Noninterest Income on the Consolidated Statements of Comprehensive Income.
Assets And Liabilities Recorded At Fair Value On A Nonrecurring Basis	The following table presents assets recorded at fair value on a nonrecurring basis at March 31, 2018 and December 31, 2017 . No liabilities were recorded at fair value on a nonrecurring basis at March 31, 2018 and December 31, 2017 . (in millions) Level 3 March 31, 2018 Loans: Commercial $ 102 Commercial mortgage 4 Total assets at fair value $ 106 December 31, 2017 Loans: Commercial $ 111 Commercial mortgage 5 Total assets at fair value $ 116
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 March 31, 2018 Assets Cash and due from banks $ 1,173 $ 1,173 $ 1,173 $ — $ — Interest-bearing deposits with banks 5,663 5,663 5,663 — — Loans held-for-sale 2 2 — 2 — Total loans, net of allowance for loan losses (a) 48,542 48,345 — — 48,345 Customers’ liability on acceptances outstanding 2 2 2 — — Restricted equity investments 248 248 248 — — Nonmarketable equity securities (b) 6 9 Liabilities Demand deposits (noninterest-bearing) 30,961 30,961 — 30,961 — Interest-bearing deposits 24,603 24,603 — 24,603 — Customer certificates of deposit 2,071 2,041 — 2,041 — Total deposits 57,635 57,605 — 57,605 — Short-term borrowings 48 48 48 — — Acceptances outstanding 2 2 2 — — Medium- and long-term debt 5,594 5,604 — 5,604 — Credit-related financial instruments (68 ) (68 ) — — (68 ) December 31, 2017 Assets Cash and due from banks $ 1,438 $ 1,438 $ 1,438 $ — $ — Interest-bearing deposits with banks 4,407 4,407 4,407 — — Investment securities held-to-maturity 1,266 1,246 — 1,246 — Loans held-for-sale 4 4 — 4 — Total loans, net of allowance for loan losses (a) 48,461 48,153 — — 48,153 Customers’ liability on acceptances outstanding 2 2 2 — — Restricted equity investments 207 207 207 — — Nonmarketable equity securities (b) 6 9 Liabilities Demand deposits (noninterest-bearing) 32,071 32,071 — 32,071 — Interest-bearing deposits 23,667 23,667 — 23,667 — Customer certificates of deposit 2,165 2,142 — 2,142 — Total deposits 57,903 57,880 — 57,880 — Short-term borrowings 10 10 10 — — Acceptances outstanding 2 2 2 — — Medium- and long-term debt 4,622 4,636 — 4,636 — Credit-related financial instruments (67 ) (67 ) — — (67 ) (a) Included $106 million and $116 million of impaired loans recorded at fair value on a nonrecurring basis at March 31, 2018 and December 31, 2017 , 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)	3 Months Ended
Investment Securities (Tables)	Mar. 31, 2018
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 March 31, 2018 Investment securities available-for-sale: U.S. Treasury and other U.S. government agency securities $ 2,744 $ — $ 38 $ 2,706 Residential mortgage-backed securities (a) 9,500 13 248 9,265 Total investment securities available-for-sale $ 12,244 $ 13 $ 286 $ 11,971 December 31, 2017 Investment securities available-for-sale: U.S. Treasury and other U.S. government agency securities $ 2,743 $ — $ 16 $ 2,727 Residential mortgage-backed securities (a) 8,230 22 128 8,124 State and municipal securities 5 — — 5 Equity and other non-debt securities 83 1 2 82 Total investment securities available-for-sale (b) $ 11,061 $ 23 $ 146 $ 10,938 Investment securities held-to-maturity (c): Residential mortgage-backed securities (a) $ 1,266 $ — $ 20 $ 1,246 (a) Issued and/or guaranteed by U.S. government agencies or U.S. government-sponsored enterprises. (b) Included auction-rate securities at amortized cost and fair value of $51 million and $49 million , respectively, as of December 31, 2017 . (c) The amortized cost of investment securities held-to-maturity included net unrealized losses of $9 million at December 31, 2017 related to securities transferred from available-for-sale in 2014, which are included in accumulated other comprehensive loss.
Summary Of Investment Securities In Unrealized Loss Positions	A summary of the Corporation’s investment securities in an unrealized loss position as of March 31, 2018 and December 31, 2017 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 March 31, 2018 U.S. Treasury and other U.S. government agency securities $ 2,706 $ 38 $ — $ — $ 2,706 $ 38 Residential mortgage-backed securities (a) 4,623 81 3,855 167 8,478 248 Total temporarily impaired securities $ 7,329 $ 119 $ 3,855 $ 167 $ 11,184 $ 286 December 31, 2017 U.S. Treasury and other U.S. government agency securities $ 2,727 $ 16 $ — $ — $ 2,727 $ 16 Residential mortgage-backed securities (a) 3,845 32 4,003 125 7,848 157 State and municipal securities (c) — — 5 — (b) 5 — (b) Equity and other non-debt securities (c) — — 44 2 44 2 Total temporarily impaired securities $ 6,572 $ 48 $ 4,052 $ 127 $ 10,624 $ 175 (a) Issued and/or guaranteed by U.S. government agencies or U.S. government-sponsored enterprises. (b) Unrealized losses less than $0.5 million. (c) Primarily auction-rate securities.
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) March 31, 2018 Amortized Cost Fair Value Contractual maturity Within one year $ 100 $ 100 After one year through five years 2,861 2,823 After five years through ten years 1,727 1,709 After ten years 7,557 7,339 Total investment securities $ 12,245 $ 11,971

Credit Quality And Allowance 26

Credit Quality And Allowance For Credit Losses (Tables)	3 Months Ended
Credit Quality And Allowance For Credit Losses (Tables)	Mar. 31, 2018
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 March 31, 2018 Business loans: Commercial $ 84 $ 29 $ 26 $ 139 $ 242 $ 30,528 $ 30,909 Real estate construction: Commercial Real Estate business line (a) 12 — — 12 — 2,746 2,758 Other business lines (b) — — — — — 356 356 Total real estate construction 12 — — 12 — 3,102 3,114 Commercial mortgage: Commercial Real Estate business line (a) 15 — — 15 9 1,882 1,906 Other business lines (b) 20 6 8 34 20 7,312 7,366 Total commercial mortgage 35 6 8 49 29 9,194 9,272 Lease financing — — — — 3 461 464 International 14 — — 14 4 946 964 Total business loans 145 35 34 214 278 44,231 44,723 Retail loans: Residential mortgage 11 1 — 12 29 1,962 2,003 Consumer: Home equity 6 2 1 9 19 1,735 1,763 Other consumer 1 — 1 2 — 749 751 Total consumer 7 2 2 11 19 2,484 2,514 Total retail loans 18 3 2 23 48 4,446 4,517 Total loans $ 163 $ 38 $ 36 $ 237 $ 326 $ 48,677 $ 49,240 December 31, 2017 Business loans: Commercial $ 79 $ 134 $ 12 $ 225 $ 309 $ 30,526 $ 31,060 Real estate construction: Commercial Real Estate business line (a) 3 — — 3 — 2,627 2,630 Other business lines (b) 4 — — 4 — 327 331 Total real estate construction 7 — — 7 — 2,954 2,961 Commercial mortgage: Commercial Real Estate business line (a) 14 — — 14 9 1,808 1,831 Other business lines (b) 27 6 22 55 22 7,251 7,328 Total commercial mortgage 41 6 22 69 31 9,059 9,159 Lease financing — — — — 4 464 468 International 13 — — 13 6 964 983 Total business loans 140 140 34 314 350 43,967 44,631 Retail loans: Residential mortgage 10 2 — 12 31 1,945 1,988 Consumer: Home equity 5 1 — 6 21 1,789 1,816 Other consumer 4 — 1 5 — 733 738 Total consumer 9 1 1 11 21 2,522 2,554 Total retail loans 19 3 1 23 52 4,467 4,542 Total loans $ 159 $ 143 $ 35 $ 337 $ 402 $ 48,434 $ 49,173 (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 March 31, 2018 Business loans: Commercial $ 29,195 $ 579 $ 893 $ 242 $ 30,909 Real estate construction: Commercial Real Estate business line (e) 2,758 — — — 2,758 Other business lines (f) 352 4 — — 356 Total real estate construction 3,110 4 — — 3,114 Commercial mortgage: Commercial Real Estate business line (e) 1,836 15 46 9 1,906 Other business lines (f) 7,144 107 95 20 7,366 Total commercial mortgage 8,980 122 141 29 9,272 Lease financing 453 5 3 3 464 International 926 5 29 4 964 Total business loans 42,664 715 1,066 278 44,723 Retail loans: Residential mortgage 1,973 1 — 29 2,003 Consumer: Home equity 1,733 — 11 19 1,763 Other consumer 750 1 — — 751 Total consumer 2,483 1 11 19 2,514 Total retail loans 4,456 2 11 48 4,517 Total loans $ 47,120 $ 717 $ 1,077 $ 326 $ 49,240 December 31, 2017 Business loans: Commercial $ 29,263 $ 591 $ 897 $ 309 $ 31,060 Real estate construction: Commercial Real Estate business line (e) 2,630 — — — 2,630 Other business lines (f) 327 4 — — 331 Total real estate construction 2,957 4 — — 2,961 Commercial mortgage: Commercial Real Estate business line (e) 1,759 20 43 9 1,831 Other business lines (f) 7,099 115 92 22 7,328 Total commercial mortgage 8,858 135 135 31 9,159 Lease financing 440 23 1 4 468 International 946 11 20 6 983 Total business loans 42,464 764 1,053 350 44,631 Retail loans: Residential mortgage 1,955 2 — 31 1,988 Consumer: Home equity 1,786 1 8 21 1,816 Other consumer 737 1 — — 738 Total consumer 2,523 2 8 21 2,554 Total retail loans 4,478 4 8 52 4,542 Total loans $ 46,942 $ 768 $ 1,061 $ 402 $ 49,173 (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 - on pages F-51 and F-52 in the Corporation's 2017 Annual Report. 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) March 31, 2018 December 31, 2017 Nonaccrual loans $ 326 $ 402 Reduced-rate loans (a) 8 8 Total nonperforming loans 334 410 Foreclosed property (b) 5 5 Total nonperforming assets $ 339 $ 415 (a) There were no reduced-rate business loans at both March 31, 2018 and December 31, 2017 . Reduced-rate retail loans were $8 million at both March 31, 2018 and December 31, 2017 . (b) Included $4 million of foreclosed residential real estate properties at both March 31, 2018 and December 31, 2017 .
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. 2018 2017 (in millions) Business Loans Retail Loans Total Business Loans Retail Loans Total Three Months Ended March 31 Allowance for loan losses: Balance at beginning of period $ 661 $ 51 $ 712 $ 682 $ 48 $ 730 Loan charge-offs (36 ) (1 ) (37 ) (42 ) (2 ) (44 ) Recoveries on loans previously charged-off 8 1 9 9 2 11 Net loan charge-offs (28 ) — (28 ) (33 ) — (33 ) Provision for loan losses 20 (6 ) 14 12 (1 ) 11 Balance at end of period $ 653 $ 45 $ 698 $ 661 $ 47 $ 708 As a percentage of total loans 1.46 % 0.99 % 1.42 % 1.51 % 1.05 % 1.47 % March 31 Allowance for loan losses: Individually evaluated for impairment $ 42 $ — $ 42 $ 87 $ 2 $ 89 Collectively evaluated for impairment 611 45 656 574 45 619 Total allowance for loan losses $ 653 $ 45 $ 698 $ 661 $ 47 $ 708 Loans: Individually evaluated for impairment $ 384 $ 31 $ 415 $ 535 $ 41 $ 576 Collectively evaluated for impairment 44,339 4,486 48,825 43,287 4,440 47,727 Total loans evaluated for impairment $ 44,723 $ 4,517 $ 49,240 $ 43,822 $ 4,481 $ 48,303
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. Three Months Ended March 31, (in millions) 2018 2017 Balance at beginning of period $ 42 $ 41 Provision for credit losses on lending-related commitments (2 ) 5 Balance at end of period $ 40 $ 46
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 March 31, 2018 Business loans: Commercial $ 159 $ 156 $ 315 $ 403 $ 39 Commercial mortgage: Commercial Real Estate business line (a) 39 1 40 49 — Other business lines (b) 3 22 25 29 3 Total commercial mortgage 42 23 65 78 3 International 3 1 4 9 — Total business loans 204 180 384 490 42 Retail loans: Residential mortgage 11 8 19 20 — Consumer: Home equity 11 — 11 13 — Other consumer 1 — 1 2 — Total consumer 12 — 12 15 — Total retail loans (c) 23 8 31 35 — Total individually evaluated impaired loans $ 227 $ 188 $ 415 $ 525 $ 42 December 31, 2017 Business loans: Commercial $ 105 $ 267 $ 372 $ 460 $ 63 Commercial mortgage: Commercial Real Estate business line (a) 39 1 40 49 — Other business lines (b) 3 22 25 29 3 Total commercial mortgage 42 23 65 78 3 International — 6 6 17 1 Total business loans 147 296 443 555 67 Retail loans: Residential mortgage 14 8 22 22 — Consumer: Home equity 11 — 11 14 — Other consumer 1 — 1 2 — Total consumer 12 — 12 16 — Total retail loans (c) 26 8 34 38 — Total individually evaluated impaired loans $ 173 $ 304 $ 477 $ 593 $ 67 (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 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 Three Months Ended March 31 Business loans: Commercial $ 344 $ 1 $ 498 $ 2 Commercial mortgage: Commercial Real Estate business line (a) 40 1 7 — Other business lines (b) 25 — 34 — Total commercial mortgage 65 1 41 — International 5 — 11 — Total business loans 414 2 550 2 Retail loans: Residential mortgage 20 — 27 — Consumer loans: Home equity 11 — 14 — Other consumer 1 — 4 — Total consumer 12 — 18 — Total retail loans 32 — 45 — Total individually evaluated impaired loans $ 446 $ 2 $ 595 $ 2 (a) Primarily loans to real estate developers. (b) Primarily loans secured by owner-occupied real estate.
Troubled Debt Restructurings By Type Of Modification	The following table details the recorded balance at March 31, 2018 and 2017 of loans considered to be troubled debt restructurings (TDRs) that were restructured during the three-month periods ended March 31, 2018 and 2017 , all of which were principal deferrals. Principal Deferrals (a) (in millions) 2018 2017 Three Months Ended March 31 Business loans: Commercial $ 28 $ 80 Commercial mortgage: Other business lines (b) 1 5 Total business loans 29 85 Retail loans: Consumer: Home equity (c) 1 1 Total loans $ 30 $ 86 (a) Primarily represents loan balances where terms were extended 90 days or more at or above contractual interest rates. (b) Primarily loans to 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.
Troubled Debt Restructuring Subsequent Default	n. The following table presents information regarding the recorded balance at March 31, 2018 and 2017 of loans modified by principal deferral during the twelve-month periods ended March 31, 2018 and 2017 . 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. There were no subsequent defaults of principal deferral loans during the three-month periods ended March 31, 2018 and 2017 . Principal Deferrals (in millions) 2018 2017 Balance at March 31, Business loans: Commercial $ 90 $ 141 Commercial mortgage: Commercial Real Estate business line (a) 37 — Other business lines (a) 2 9 Total commercial mortgage 39 9 Total business loans 129 150 Retail loans: Consumer: Home equity (b) 2 2 Total principal deferrals $ 131 $ 152 (a) Primarily loans secured by owner-occupied real estate. (b) Includes bankruptcy loans for which the court has discharged the borrower's obligation and the borrower has not reaffirmed the debt.

Derivative And Credit-Related27

Derivative And Credit-Related Financial Instruments (Tables)	3 Months Ended
	Mar. 31, 2018
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 March 31, 2018 and December 31, 2017 . The table excludes commitments and warrants accounted for as derivatives. March 31, 2018 December 31, 2017 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 $ 1,775 $ — $ 3 $ 1,775 $ — $ 2 Derivatives used as economic hedges Foreign exchange contracts: Spot, forwards and swaps 647 — — 650 — 2 Total risk management purposes 2,422 — 3 2,425 — 4 Customer-initiated and other activities Interest rate contracts: Caps and floors written 582 — 2 635 — — Caps and floors purchased 582 2 — 635 — — Swaps 12,454 31 93 13,119 57 57 Total interest rate contracts 13,618 33 95 14,389 57 57 Energy contracts: Caps and floors written 135 — 11 164 — 11 Caps and floors purchased 135 11 — 164 11 — Swaps 1,755 96 95 1,519 82 80 Total energy contracts 2,025 107 106 1,847 93 91 Foreign exchange contracts: Spot, forwards, options and swaps 1,976 37 32 1,884 42 38 Total customer-initiated and other activities 17,619 177 233 18,120 192 186 Total gross derivatives $ 20,041 $ 177 $ 236 $ 20,545 $ 192 $ 190 Amounts offset in the Consolidated Balance Sheets: Netting adjustment - Offsetting derivative assets/liabilities (49 ) (49 ) (49 ) (49 ) Netting adjustment - Cash collateral received/posted (5 ) (62 ) (1 ) (39 ) Net derivatives included in the Consolidated Balance Sheets (b) 123 125 142 102 Amounts not offset in the Consolidated Balance Sheets: Marketable securities pledged under bilateral collateral agreements (5 ) (11 ) (3 ) (24 ) Net derivatives after deducting amounts not offset in the Consolidated Balance Sheets $ 118 $ 114 $ 139 $ 78 (a) Notional or contractual amounts, which represent the extent of involvement in the derivatives market, are used to determine the contractual cash flows required in accordance with the terms of the agreement. These amounts are typically not exchanged, significantly exceed amounts subject to credit or market risk and are not reflected in the Consolidated Balance Sheets. (b) Net derivative assets are included in accrued income and other assets and net derivative liabilities are included in accrued expenses and other liabilities on the Consolidated Balance Sheets. Included in the fair value of net derivative assets and net derivative liabilities are credit valuation adjustments reflecting counterparty credit risk and credit risk of the Corporation. The fair value of net derivative assets included credit valuation adjustments for counterparty credit risk of $3 million and $4 million at March 31, 2018 and December 31, 2017 , respectively.
Schedule of the Effects of Fair Value Hedging on the Consolidated Statements of Comprehensive Income	The following table details the effects of fair value hedging on the Consolidated Statements of Comprehensive Income. Interest on Medium- and Long-Term Debt Three Months Ended March 31, (in millions) 2018 2017 Total interest on medium-and long-term debt (a) $ 25 $ 17 Fair value hedging relationships: Interest rate contracts: Hedged items 15 22 Derivatives designated as hedging instruments (3 ) (10 ) (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 March 31, 2018 and December 31, 2017 . Weighted Average (dollar amounts in millions) Derivative Notional Amount Carrying Value of Hedged Items (a) Remaining Maturity (in years) Receive Rate Pay Rate (b) March 31, 2018 Swaps - fair value - receive fixed/pay floating rate Medium- and long-term debt $ 1,775 $ 1,794 4.4 3.26 % 2.59 % December 31, 2017 Swaps - fair value - receive fixed/pay floating rate Medium- and long-term debt 1,775 1,822 4.6 3.26 2.35 (a) Included $ 27 million and $ 56 million of cumulative hedging adjustments at March 31, 2018 and December 31, 2017 , respectively, which included $ 8 million and $ 9 million , respectively, of hedging adjustment on a discontinued hedging relationship.
Schedule Of Net Gains Recognized In Income On Customer-Initiated Derivatives	The net gains recognized in income on customer-initiated derivative instruments, net of the impact of offsetting positions, were as follows . Three Months Ended March 31, (in millions) Location of Gain 2018 2017 Interest rate contracts Other noninterest income $ 4 $ 6 Foreign exchange contracts Foreign exchange income 12 11 Total $ 16 $ 17
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) March 31, 2018 December 31, 2017 Unused commitments to extend credit: Commercial and other $ 22,169 $ 22,636 Bankcard, revolving check credit and home equity loan commitments 2,838 2,833 Total unused commitments to extend credit $ 25,007 $ 25,469 Standby letters of credit $ 3,245 $ 3,228 Commercial letters of credit 37 39
Summary Of Criticized Letters Of Credit	The following table presents a summary of criticized standby and commercial letters of credit at March 31, 2018 and December 31, 2017 . The Corporation's criticized list is generally consistent with the Special Mention, Substandard and Doubtful categories defined by regulatory authorities. The Corporation manages credit risk through underwriting, periodically reviewing and approving its credit exposures using Board committee approved credit policies and guidelines. (dollar amounts in millions) March 31, 2018 December 31, 2017 Total criticized standby and commercial letters of credit $ 77 $ 88 As a percentage of total outstanding standby and commercial letters of credit 2.4 % 2.7 %

Variable Interest Entities (V28

Variable Interest Entities (VIEs) (Tables)	3 Months Ended
Variable Interest Entities (VIEs) (Tables)	Mar. 31, 2018
Variable Interest Entity, Not Primary Beneficiary, Disclosures [Abstract]
Impact Of VIEs On The Consolidated Statements Of Comprehensive Income	The following table summarizes the impact of these tax credit entities on line items on the Corporation’s Consolidated Statements of Comprehensive Income. Three Months Ended March 31, (in millions) 2018 2017 Other noninterest income: Amortization of other tax credit investments $ 1 $ 1 Provision for income taxes: Amortization of LIHTC investments 15 16 Low income housing tax credits (15 ) (15 ) Other tax benefits related to tax credit entities (3 ) (6 ) Total provision for income taxes $ (3 ) $ (5 )

Medium- And Long-Term Debt (Tab

Medium- And Long-Term Debt (Tables)	3 Months Ended
Medium- And Long-Term Debt (Tables)	Mar. 31, 2018
Debt Disclosure [Abstract]
Schedule Of Medium- And Long-Term Debt	Medium- and long-term debt is summarized as follows: (in millions) March 31, 2018 December 31, 2017 Parent company Subordinated notes: 3.80% subordinated notes due 2026 (a) $ 248 $ 255 Medium-term notes: 2.125% notes due 2019 (a) 346 347 Total parent company 594 602 Subsidiaries Subordinated notes: 4.00% subordinated notes due 2025 (a) 339 347 7.875% subordinated notes due 2026 (a) 201 208 Total subordinated notes 540 555 Medium-term notes: 2.50% notes due 2020 (a) 660 665 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 — Total FHLB advances 3,800 2,800 Total subsidiaries 5,000 4,020 Total medium- and long-term debt $ 5,594 $ 4,622 (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.

Accumulated Other Comprehensi30

Accumulated Other Comprehensive Loss (Tables)	3 Months Ended
Accumulated Other Comprehensive Loss (Tables)	Mar. 31, 2018
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Schedule Of Accumulated Other Comprehensive Loss	The following table presents a reconciliation of the changes in the components of accumulated other comprehensive loss and details the components of other comprehensive income (loss) for the three months ended March 31, 2018 and 2017 , including the amount of income tax expense (benefit) allocated to each component of other comprehensive income (loss). Three Months Ended March 31, (in millions) 2018 2017 Accumulated net unrealized losses on investment securities: Balance at beginning of period, net of tax $ (101 ) $ (33 ) Cumulative effect of change in accounting principle 1 — Net unrealized holding losses arising during the period (142 ) (2 ) Less: Benefit for income taxes (33 ) (1 ) Net unrealized holding losses arising during the period, net of tax (109 ) (1 ) Less: Reclassification adjustment for net losses realized as a yield adjustment included in net income, net of tax — (1 ) Change in net unrealized losses on investment securities, net of tax (109 ) — Balance at end of period, net of tax $ (209 ) $ (33 ) Accumulated defined benefit pension and other postretirement plans adjustment: Balance at beginning of period, net of tax $ (350 ) $ (350 ) Amortization of actuarial net loss 15 13 Amortization of prior service credit (7 ) (7 ) Amounts recognized in other noninterest expense 8 6 Less: Provision for income taxes 2 2 Change in defined benefit pension and other postretirement plans adjustment, net of tax 6 4 Balance at end of period, net of tax $ (344 ) $ (346 ) Total accumulated other comprehensive loss at end of period, net of tax $ (553 ) $ (379 )

Net Income Per Common Share (Ta

Net Income Per Common Share (Tables)	3 Months Ended
Net Income Per Common Share (Tables)	Mar. 31, 2018
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. Three Months Ended March 31, (in millions, except per share data) 2018 2017 Basic and diluted Net income $ 281 $ 202 Less: Income allocated to participating securities 2 2 Net income attributable to common shares $ 279 $ 200 Basic average common shares 172 175 Basic net income per common share $ 1.62 $ 1.15 Basic average common shares 172 175 Dilutive common stock equivalents: Net effect of the assumed exercise of stock options 2 3 Net effect of the assumed exercise of warrants 1 2 Diluted average common shares 175 180 Diluted net income per common share $ 1.59 $ 1.11

Employee Benefit Plans (Tables)

Employee Benefit Plans (Tables)	3 Months Ended
Employee Benefit Plans (Tables)	Mar. 31, 2018
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Abstract]
Components of Net Periodic Benefit Cost	The components of net periodic benefit cost (credit) for the Corporation's qualified pension plan, non-qualified pension plan and postretirement benefit plan are as follows. Qualified Defined Benefit Pension Plan Three Months Ended March 31, (in millions) 2018 2017 Service cost $ 7 $ 7 Other components of net benefit credit: Interest cost 19 20 Expected return on plan assets (41 ) (40 ) Amortization of prior service credit (5 ) (5 ) Amortization of net loss 13 11 Total other components of net benefit credit (14 ) (14 ) Net periodic defined benefit credit $ (7 ) $ (7 ) Non-Qualified Defined Benefit Pension Plan Three Months Ended March 31, (in millions) 2018 2017 Service cost $ — $ 1 Other components of net benefit cost: Interest cost 2 2 Amortization of prior service credit (2 ) (2 ) Amortization of net loss 2 2 Total other components of net benefit cost 2 2 Net periodic defined benefit cost $ 2 $ 3 Postretirement Benefit Plan Three Months Ended March 31, (in millions) 2018 2017 Other components of net benefit cost: Interest cost $ 1 $ 1 Expected return on plan assets (1 ) (1 ) Net periodic defined benefit cost $ — $ —

Restructuring Charges (Tables)

Restructuring Charges (Tables)	3 Months Ended
Restructuring Charges (Tables)	Mar. 31, 2018
Restructuring and Related Activities [Abstract]
Restructuring and Related Costs	The following table presents changes in restructuring reserves, cumulative charges incurred to date and total expected restructuring charges: (in millions) Employee Costs Facilities Costs Technology Costs Other Costs Total Three Months Ended March 31, 2018 Balance at beginning of period $ 8 $ — $ 6 $ 1 $ 15 Restructuring charges 5 1 10 — 16 Payments (3 ) (1 ) (7 ) (1 ) (12 ) Balance at end of period $ 10 $ — $ 9 $ — $ 19 Three Months Ended March 31, 2017 Balance at beginning of period $ 10 $ 4 $ — $ 4 $ 18 Restructuring charges 1 1 6 3 11 Payments (4 ) (5 ) — (4 ) (13 ) Adjustments for non-cash charges (a) — — (3 ) — (3 ) Balance at end of period $ 7 $ — $ 3 $ 3 $ 13 Total restructuring charges incurred to date $ 67 $ 18 $ 36 $ 33 $ 154 Total expected restructuring charges (b) 70 20 - 25 60 - 65 35 185 - 195 (a) Adjustments for non-cash charges primarily relate to impairments of previously capitalized software costs in Technology Costs. (b) Restructuring activities are expected to be substantially completed by 12/31/2018 .

Business Segment Information (T

Business Segment Information (Tables)	3 Months Ended
Business Segment Information (Tables)	Mar. 31, 2018
Segment Reporting [Abstract]
Business Segment Financial Results	Business segment financial results are as follows: (dollar amounts in millions) Business Retail Wealth Management Finance Other Total Three Months Ended March 31, 2018 Earnings summary: Net interest income $ 330 $ 165 $ 41 $ 1 $ 12 $ 549 Provision for credit losses 10 4 (4 ) — 2 12 Noninterest income 121 42 68 11 2 244 Noninterest expenses 184 177 72 (1 ) 14 446 Provision (benefit) for income taxes 59 6 10 1 (22 ) (a) 54 Net income $ 198 $ 20 $ 31 $ 12 $ 20 $ 281 Net credit-related charge-offs (recoveries) $ 18 $ 12 $ (2 ) $ — $ — $ 28 Selected average balances: Assets $ 38,911 $ 6,427 $ 5,373 $ 13,779 $ 5,836 $ 70,326 Loans 37,368 5,807 5,246 — — 48,421 Deposits 27,314 24,064 3,796 823 93 56,090 Statistical data: Return on average assets (b) 2.07 % 0.33 % 2.30 % N/M N/M 1.62 % Efficiency ratio (c) 40.72 85.03 67.10 N/M N/M 56.33 (dollar amounts in millions) Business Retail Wealth Management Finance Other Total Three Months Ended March 31, 2017 Earnings summary: Net interest income (expense) $ 332 $ 160 $ 41 $ (71 ) $ 8 $ 470 Provision for credit losses 10 12 (1 ) — (5 ) 16 Noninterest income 144 48 64 11 4 271 Noninterest expenses 197 179 70 (1 ) 12 457 Provision (benefit) for income taxes 92 6 13 (24 ) (21 ) (a) 66 Net income (loss) $ 177 $ 11 $ 23 $ (35 ) $ 26 $ 202 Net credit-related charge-offs (recoveries) $ 30 $ 5 $ (2 ) $ — $ — $ 33 Selected average balances: Assets $ 38,091 $ 6,525 $ 5,406 $ 13,944 $ 7,853 $ 71,819 Loans 36,754 5,895 5,251 — — 47,900 Deposits 29,648 23,795 3,978 142 216 57,779 Statistical data: Return on average assets (b) 1.89 % 0.18 % 1.71 % N/M N/M 1.14 % Efficiency ratio (c) 41.39 86.01 67.17 N/M N/M 61.71 (a) Included tax benefits from employee stock transactions of $19 million and $24 million for the three months ended March 31, 2018 and 2017, respectively. (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 securities gains (losses). N/M – not meaningful
Market Segment Financial Results	Market segment financial results are as follows: (dollar amounts in millions) Michigan California Texas Other Finance Total Three Months Ended March 31, 2018 Earnings summary: Net interest income $ 169 $ 180 $ 109 $ 78 $ 13 $ 549 Provision for credit losses 33 (2 ) (13 ) (8 ) 2 12 Noninterest income 73 39 31 88 13 244 Noninterest expenses 144 106 92 91 13 446 Provision (benefit) for income taxes 16 30 14 15 (21 ) (a) 54 Net income $ 49 $ 85 $ 47 $ 68 $ 32 $ 281 Net credit-related charge-offs (recoveries) $ (1 ) $ 13 $ 5 $ 11 $ — $ 28 Selected average balances: Assets $ 13,395 $ 18,581 $ 10,373 $ 8,362 $ 19,615 $ 70,326 Loans 12,604 18,347 9,830 7,640 — 48,421 Deposits 21,227 17,091 9,188 7,668 916 56,090 Statistical data: Return on average assets (b) 0.88 % 1.86 % 1.85 % 3.32 % N/M 1.62 % Efficiency ratio (c) 59.61 48.39 65.63 54.97 N/M 56.33 (dollar amounts in millions) Michigan California Texas Other Finance Total Three Months Ended March 31, 2017 Earnings summary: Net interest income (expense) $ 170 $ 171 $ 113 $ 79 $ (63 ) $ 470 Provision for credit losses (2 ) 21 (9 ) 11 (5 ) 16 Noninterest income 83 41 32 100 15 271 Noninterest expenses 150 96 94 106 11 457 Provision (benefit) for income taxes 37 36 22 16 (45 ) (a) 66 Net income (loss) $ 68 $ 59 $ 38 $ 46 $ (9 ) $ 202 Net credit-related charge-offs (recoveries) $ (3 ) $ 10 $ 22 $ 4 $ — $ 33 Selected average balances: Assets $ 13,254 $ 17,958 $ 10,555 $ 8,255 $ 21,797 $ 71,819 Loans 12,586 17,680 10,111 7,523 — 47,900 Deposits 22,150 17,243 10,113 7,915 358 57,779 Statistical data: Return on average assets (b) 1.20 % 1.32 % 1.35 % 2.13 % N/M 1.14 % Efficiency ratio (c) 59.50 45.25 64.80 59.31 N/M 61.71 (a) Included tax benefits from employee stock transactions of $19 million and $24 million for the three months ended March 31, 2018 and 2017, respectively. (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 securities gains (losses). N/M – not meaningful

Revenue from Contracts with C35

Revenue from Contracts with Customers Revenue from Contracts with Customers (Tables)	3 Months Ended
	Mar. 31, 2018
Revenue from Contract with Customer [Abstract]
Composition of Revenue from Contracts with Customers	The following table presents the composition of revenue from contracts with customers, segregated from other sources of noninterest income, by business segment. Business Bank Retail Bank Wealth Management Finance & Other Total (in millions) Three Months Ended March 31, 2018 Revenue from contracts with customers: Card fees (a) $ 47 $ 11 $ 1 $ — $ 59 Service charges on deposit accounts (a) 30 23 1 — 54 Fiduciary income — — 52 — 52 Commercial loan servicing fees (b) 4 — — — 4 Brokerage fees — — 7 — 7 Other noninterest income (c) 3 5 4 — 12 Total revenue from contracts with customers 84 39 65 — 188 Other sources of noninterest income 37 3 3 13 56 Total noninterest income $ 121 $ 42 $ 68 $ 13 $ 244 Three Months Ended March 31, 2017 Revenue from contracts with customers: Card fees $ 64 $ 12 $ 1 $ — $ 77 Service charges on deposit accounts 32 25 1 — 58 Fiduciary income — — 49 — 49 Commercial loan servicing fees (b) 3 — — — 3 Brokerage fees — — 5 — 5 Other noninterest income (c) 4 8 5 — 17 Total revenue from contracts with customers 103 45 61 — 209 Other sources of noninterest income 41 3 3 15 62 Total noninterest income $ 144 $ 48 $ 64 $ 15 $ 271 (a) 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 $34 million and service charges on deposit accounts by $1 million for the first quarter 2018. Refer to note 1 for further information. (b) Included in commercial lending fees on the Consolidated Statements of Comprehensive Income. (c) Excludes derivative, warrant and other miscellaneous income.

Basis of Presentation and Acc36

Basis of Presentation and Accounting Policies Basis of Presentation and Accounting Policies (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended			12 Months Ended
	Mar. 31, 2018		Mar. 31, 2017	Dec. 31, 2017	Jan. 01, 2018	Dec. 31, 2016
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect of changes to retained earnings as a result of adoption of ASU	$ 8,000		$ 7,930	$ 7,963		$ 7,796
Network costs to be presented net of card fee revenue	59	[1]	77
Proceeds from settlement of BOLI policies	3		3
Remeasurement of the Corporation's deferred tax balance	104			$ 107
Deferred tax balance downward revision to the estimated impact	3
Accounting Standards Codification (ASC) Topic 606
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Decrease in card fees due to change in presentation	34
Decrease in service charges on deposit accounts due to change in presentation	1
Decrease in processing fee expense due to change in presentation	35
Treasury management fee transition adjustment to retained earnings					$ 14
Cumulative effect of changes to retained earnings as a result of adoption of ASU					$ 2
Network costs to be presented net of card fee revenue	34		$ 25
Accounting Standards Update 2016-15
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Proceeds from settlement of BOLI policies	3
Accounting Standards Update 2017-07
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Other components of net benefit cost to be reclassified	12
Accounting Standards Update 2017-12
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect of change to retained earnings as a result of adoption of ASU	1
Recognition of additional unrealized losses from the transfer of Held-to-maturity to Available-for-sale securities	$ 11

[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 $34 million and service charges on deposit accounts by $1 million for the first quarter 2018. Refer to note 1 for further information.

Fair Value Measurements (Narrat

Fair Value Measurements (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Recurring
Transfers into or out of Level 1 or Level 2 or Level 3	$ 0	$ 0
Total liabilities at fair value	329		$ 282
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		Mar. 31, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available-for-sale		$ 11,971	$ 10,938	[1]
Derivative assets		177	192
Derivative liabilities	[2]	125	102
Equity and other non-debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available-for-sale			82
U.S. Treasury and other U.S. government agency securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available-for-sale		2,706	2,727
Residential mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available-for-sale	[3]	9,265	8,124
State and municipal securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available-for-sale			5
Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available-for-sale		11,971	10,938
Derivative assets		179	194
Total assets at fair value		12,281	11,224
Derivative liabilities		236	190
Deferred compensation plan liabilities		93	92
Total liabilities at fair value		329	282
Recurring \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available-for-sale		2,706	2,765
Derivative assets		0	0
Total assets at fair value		2,837	2,857
Derivative liabilities		0	0
Deferred compensation plan liabilities		93	92
Total liabilities at fair value		93	92
Recurring \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available-for-sale		9,265	8,124
Derivative assets		170	178
Total assets at fair value		9,435	8,302
Derivative liabilities		236	190
Deferred compensation plan liabilities		0	0
Total liabilities at fair value		236	190
Recurring \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available-for-sale		0	49
Derivative assets		9	16
Total assets at fair value		9	65
Derivative liabilities		0	0
Deferred compensation plan liabilities		0	0
Total liabilities at fair value		0	0
Recurring \| Interest rate contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		33	57
Derivative liabilities		98	59
Recurring \| Interest rate contracts \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		0	0
Derivative liabilities		0	0
Recurring \| Interest rate contracts \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		26	43
Derivative liabilities		98	59
Recurring \| Interest rate contracts \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		7	14
Derivative liabilities		0	0
Recurring \| Energy derivative contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		107	93
Derivative liabilities		106	91
Recurring \| Energy derivative contracts \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		0	0
Derivative liabilities		0	0
Recurring \| Energy derivative contracts \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		107	93
Derivative liabilities		106	91
Recurring \| Energy derivative contracts \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		0	0
Derivative liabilities		0	0
Recurring \| Foreign exchange contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		37	42
Derivative liabilities		32	40
Recurring \| Foreign exchange contracts \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		0	0
Derivative liabilities		0	0
Recurring \| Foreign exchange contracts \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		37	42
Derivative liabilities		32	40
Recurring \| Foreign exchange contracts \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		0	0
Derivative liabilities		0	0
Recurring \| Warrants
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		2	2
Recurring \| Warrants \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		0	0
Recurring \| Warrants \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		0	0
Recurring \| Warrants \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		2	2
Recurring \| Deferred compensation plan assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading securities		93	92
Recurring \| Deferred compensation plan assets \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading securities		93	92
Recurring \| Deferred compensation plan assets \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading securities		0	0
Recurring \| Deferred compensation plan assets \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading securities		0	0
Recurring \| Equity and other non-debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other equity securities		38
Investment securities available-for-sale			82
Recurring \| Equity and other non-debt securities \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other equity securities		38
Investment securities available-for-sale			38
Recurring \| Equity and other non-debt securities \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other equity securities		0
Investment securities available-for-sale			0
Recurring \| Equity and other non-debt securities \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other equity securities		0
Recurring \| U.S. Treasury and other U.S. government agency securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available-for-sale		2,706	2,727
Recurring \| U.S. Treasury and other U.S. government agency securities \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available-for-sale		2,706	2,727
Recurring \| U.S. Treasury and other U.S. government agency securities \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available-for-sale		0	0
Recurring \| U.S. Treasury and other U.S. government agency securities \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available-for-sale		0	0
Recurring \| Residential mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available-for-sale	[4]	9,265	8,124
Recurring \| Residential mortgage-backed securities \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available-for-sale	[4]	0	0
Recurring \| Residential mortgage-backed securities \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available-for-sale	[4]	9,265	8,124
Recurring \| Residential mortgage-backed securities \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available-for-sale	[4]	$ 0	0
Recurring \| State and municipal securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available-for-sale			5
Recurring \| State and municipal securities \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available-for-sale			0
Recurring \| State and municipal securities \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available-for-sale			0
Equity and other non-debt securities \| Recurring \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available-for-sale	[5]		44
State and municipal securities \| Recurring \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available-for-sale	[5]		$ 5

[1]	Included auction-rate securities at amortized cost and fair value of $51 million and $49 million, respectively, as of December 31, 2017.
[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 $3 million and $4 million at March 31, 2018 and December 31, 2017, respectively.
[3]	Issued and/or guaranteed by U.S. government agencies or U.S. government-sponsored enterprises.
[4]	Issued and/or guaranteed by U.S. government agencies or U.S. government-sponsored enterprises.
[5]	Auction-rate securities.

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		3 Months Ended
		Mar. 31, 2018		Mar. 31, 2017
Change in classification		$ (81)		$ 0
Interest rate contracts
Balance at beginning of period		14		11
Change in classification	[1]	0		0
Realized gains (losses) recorded in earnings		0		0
Unrealized gains (losses) recorded in earnings		(7)	[2]	0
Redemptions		0		0
Balance at end of period		7		11
Warrants
Balance at beginning of period		2		3
Change in classification	[1]	0		0
Realized gains (losses) recorded in earnings		0		1	[2]
Unrealized gains (losses) recorded in earnings		0		(1)	[2]
Redemptions		0		(1)
Balance at end of period		2		2
Investment Securities Available-For-Sale
Balance at beginning of period		49		54
Change in classification	[1]	(44)		0
Realized gains (losses) recorded in earnings		0		0
Unrealized gains (losses) recorded in earnings		0		0
Redemptions		(5)		(3)
Balance at end of period		0		51
Equity and other non-debt securities \| Equity and other non-debt securities
Balance at beginning of period	[2]	0
Change in classification	[1]	(44)
Realized gains (losses) recorded in earnings	[2]	0
Unrealized gains (losses) recorded in earnings	[2]	0
Redemptions	[2]	(44)
Balance at end of period	[2]	0
Equity and other non-debt securities \| Investment Securities Available-For-Sale
Balance at beginning of period	[3]	44		47
Change in classification	[1],[3]	(44)		0
Realized gains (losses) recorded in earnings	[3]	0		0
Unrealized gains (losses) recorded in earnings	[3]	0		0
Redemptions	[3]	0		(1)
Balance at end of period	[3]	0		46	[2]
State and municipal securities \| Investment Securities Available-For-Sale
Balance at beginning of period	[3]	5		7
Change in classification	[1],[3]	0		0
Realized gains (losses) recorded in earnings	[3]	0		0
Unrealized gains (losses) recorded in earnings	[3]	0		0
Redemptions	[3]	(5)		(2)
Balance at end of period	[3]	$ 0		$ 5

[1]	Reflects the reclassification of equity securities resulting from the adoption of ASU 2016-01.
[2]	Realized and unrealized gains and losses due to changes in fair value recorded in Other Noninterest Income on the Consolidated Statements of Comprehensive Income.
[3]	Auction-rate securities.

Fair Value Measurements (Asse40

Fair Value Measurements (Assets And Liabilities Recorded At Fair Value On A Nonrecurring Basis) (Details) - Nonrecurring - Level 3 - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets at fair value	$ 106	$ 116
Commercial borrower \| Domestic loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans	102	111
Commercial borrower \| Commercial Mortgage Loans \| Domestic loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans	$ 4	$ 5

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		Mar. 31, 2018	Dec. 31, 2017
Cash and due from banks		$ 1,173	$ 1,438
Interest-bearing deposits with banks		5,663	4,407
Investment securities held-to-maturity		0	1,266
Total loans, net of allowance for loan losses		48,542	48,461
Demand deposits (noninterest-bearing)		30,961	32,071
Customer certificates of deposit		2,071	2,165
Total deposits		57,635	57,903
Short-term borrowings		48	10
Medium- and long-term debt		5,594	4,622
Carrying Amount
Cash and due from banks		1,173	1,438
Interest-bearing deposits with banks		5,663	4,407
Investment securities held-to-maturity			1,266
Loans held-for-sale		2	4
Total loans, net of allowance for loan losses	[1]	48,542	48,461
Customers' liability on acceptances outstanding		2	2
Restricted equity investments		248	207
Nonmarketable equity securities	[2]	6	6
Demand deposits (noninterest-bearing)		30,961	32,071
Interest-bearing deposits		24,603	23,667
Customer certificates of deposit		2,071	2,165
Total deposits		57,635	57,903
Short-term borrowings		48	10
Acceptances outstanding		2	2
Medium- and long-term debt		5,594	4,622
Credit-related financial instruments		(68)	(67)
Estimated Fair Value
Cash and due from banks		1,173	1,438
Interest-bearing deposits with banks		5,663	4,407
Investment securities held-to-maturity			1,246
Loans held-for-sale		2	4
Total loans, net of allowance for loan losses	[1]	48,345	48,153
Customers' liability on acceptances outstanding		2	2
Restricted equity investments		248	207
Nonmarketable equity securities	[2]	9	9
Demand deposits (noninterest-bearing)		30,961	32,071
Interest-bearing deposits		24,603	23,667
Customer certificates of deposit		2,041	2,142
Total deposits		57,605	57,880
Short-term borrowings		48	10
Acceptances outstanding		2	2
Medium- and long-term debt		5,604	4,636
Credit-related financial instruments		(68)	(67)
Level 1 \| Estimated Fair Value
Cash and due from banks		1,173	1,438
Interest-bearing deposits with banks		5,663	4,407
Investment securities held-to-maturity			0
Loans held-for-sale		0	0
Total loans, net of allowance for loan losses	[1]	0	0
Customers' liability on acceptances outstanding		2	2
Restricted equity investments		248	207
Demand deposits (noninterest-bearing)		0	0
Interest-bearing deposits		0	0
Customer certificates of deposit		0	0
Total deposits		0	0
Short-term borrowings		48	10
Acceptances outstanding		2	2
Medium- and long-term debt		0	0
Credit-related financial instruments		0	0
Level 2 \| Estimated Fair Value
Cash and due from banks		0	0
Interest-bearing deposits with banks		0	0
Investment securities held-to-maturity			1,246
Loans held-for-sale		2	4
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)		30,961	32,071
Interest-bearing deposits		24,603	23,667
Customer certificates of deposit		2,041	2,142
Total deposits		57,605	57,880
Short-term borrowings		0	0
Acceptances outstanding		0	0
Medium- and long-term debt		5,604	4,636
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
Investment securities held-to-maturity			0
Loans held-for-sale		0	0
Total loans, net of allowance for loan losses	[1]	48,345	48,153
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
Total deposits		0	0
Short-term borrowings		0	0
Acceptances outstanding		0	0
Medium- and long-term debt		0	0
Credit-related financial instruments		(68)	(67)
Nonrecurring
Total loans, net of allowance for loan losses		$ 106	$ 116

[1]	Included $106 million and $116 million of impaired loans recorded at fair value on a nonrecurring basis at March 31, 2018 and December 31, 2017, 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
Investment Securities (Narrative) (Details) $ in Millions		Mar. 31, 2018USD ($)Security	Mar. 31, 2017USD ($)	Jan. 01, 2018USD ($)	Dec. 31, 2017USD ($)
Residential mortgage-backed securities transferred from held-to-maturity to available-for-sale		$ 1,266	$ 0
Securities with no credit impairment in unrealized loss position \| Security		377
Investment securities available-for-sale, Amortized Cost		$ 12,244			$ 11,061	[1]
Investment securities available-for-sale, Fair Value		11,971			10,938	[1]
Carrying value of securities pledged		628
Liabilities secured by pledged collateral		$ 311
U.S. Treasury and other U.S. government agency securities
Securities with no credit impairment in unrealized loss position		29
Investment securities available-for-sale, Amortized Cost		$ 2,744			2,743
Investment securities available-for-sale, Fair Value		$ 2,706			2,727
Residential mortgage-backed securities
Securities with no credit impairment in unrealized loss position \| Security		348
Investment securities available-for-sale, Amortized Cost	[2]	$ 9,500			8,230
Investment securities available-for-sale, Fair Value	[2]	9,265			8,124
Equity and other non-debt securities
Securities gains		0
Securities losses		0
Investment securities available-for-sale, Amortized Cost					83
Investment securities available-for-sale, Fair Value					$ 82
Debt securities
Securities gains		0	0
Securities losses		0	$ 0
Investment securities available-for-sale, Amortized Cost		12,245
Investment securities available-for-sale, Fair Value		11,971
Prepayment options \| Residential mortgage-backed securities
Investment securities available-for-sale, Amortized Cost		0
Investment securities available-for-sale, Fair Value		$ 0
Accounting Standards Update 2016-01 \| Residential mortgage-backed securities
Residential mortgage-backed securities transferred from held-to-maturity to available-for-sale				$ 1,266

[1]	Included auction-rate securities at amortized cost and fair value of $51 million and $49 million, respectively, as of December 31, 2017.
[2]	Issued and/or guaranteed by U.S. government agencies or U.S. government-sponsored enterprises.

Investment Securities (Summary

Investment Securities (Summary Of Investment Securities Available-For-Sale) (Details) - USD ($) $ in Millions		Mar. 31, 2018	Dec. 31, 2017
Investment securities available-for-sale, Amortized Cost		$ 12,244	$ 11,061	[1]
Investment securities available-for-sale securities, Gross Unrealized Gains		13	23	[1]
Investment securities available-for-sale securities, Gross Unrealized Losses		286	146	[1]
Investment securities available-for-sale, Fair Value		11,971	10,938	[1]
Investment securities held-to-maturity, Amortized Cost		0	1,266
Net unrealized losses on available-for-sale securities transferred to held-to-maturity			9
U.S. Treasury and other U.S. government agency securities
Investment securities available-for-sale, Amortized Cost		2,744	2,743
Investment securities available-for-sale securities, Gross Unrealized Gains		0	0
Investment securities available-for-sale securities, Gross Unrealized Losses		38	16
Investment securities available-for-sale, Fair Value		2,706	2,727
Residential mortgage-backed securities
Investment securities available-for-sale, Amortized Cost	[2]	9,500	8,230
Investment securities available-for-sale securities, Gross Unrealized Gains	[2]	13	22
Investment securities available-for-sale securities, Gross Unrealized Losses	[2]	248	128
Investment securities available-for-sale, Fair Value	[2]	9,265	8,124
Investment securities held-to-maturity, Amortized Cost	[2],[3]		1,266
Investment securities held-to-maturity, Gross Unrealized Gains	[2],[3]		0
Investment securities held-to-maturity, Gross Unrealized Losses	[2],[3]		20
Investment securities held-to-maturity, Fair Value	[2],[3]		1,246
State and municipal securities
Investment securities available-for-sale, Amortized Cost			5
Investment securities available-for-sale securities, Gross Unrealized Gains			0
Investment securities available-for-sale securities, Gross Unrealized Losses			0
Investment securities available-for-sale, Fair Value			5
Equity and other non-debt securities
Investment securities available-for-sale, Amortized Cost			83
Investment securities available-for-sale securities, Gross Unrealized Gains			1
Investment securities available-for-sale securities, Gross Unrealized Losses			2
Investment securities available-for-sale, Fair Value			82
Auction-rate securities
Investment securities available-for-sale, Amortized Cost		0	51
Investment securities available-for-sale, Fair Value		$ 0	$ 49

[1]	Included auction-rate securities at amortized cost and fair value of $51 million and $49 million, respectively, as of December 31, 2017.
[2]	Issued and/or guaranteed by U.S. government agencies or U.S. government-sponsored enterprises.
[3]	The amortized cost of investment securities held-to-maturity included net unrealized losses of $9 million at December 31, 2017 related to securities transferred from available-for-sale in 2014, which are included in accumulated other comprehensive loss.

Investment Securities (Summar44

Investment Securities (Summary Of Investment Securities Available-For-Sale In Unrealized Loss Positions) (Details) - USD ($) $ in Millions		Mar. 31, 2018	Dec. 31, 2017
Temporarily Impaired Less than 12 months, Fair Value		$ 7,329	$ 6,572
Temporarily Impaired Less than 12 Months, Unrealized Losses		119	48
Temporarily Impaired 12 months or more, Fair Value		3,855	4,052
Temporarily Impaired 12 Months or more, Unrealized Losses		167	127
Temporarily Impaired Total, Fair Value		11,184	10,624
Temporarily Impaired Total, Unrealized Losses		286	175
U.S. Treasury and other U.S. government agency securities
Temporarily Impaired Less than 12 months, Fair Value		2,706	2,727
Temporarily Impaired Less than 12 Months, Unrealized Losses		38	16
Temporarily Impaired 12 months or more, Fair Value		0	0
Temporarily Impaired 12 Months or more, Unrealized Losses		0	0
Temporarily Impaired Total, Fair Value		2,706	2,727
Temporarily Impaired Total, Unrealized Losses		38	16
Residential mortgage-backed securities
Temporarily Impaired Less than 12 months, Fair Value	[1]	4,623	3,845
Temporarily Impaired Less than 12 Months, Unrealized Losses	[1]	81	32
Temporarily Impaired 12 months or more, Fair Value	[1]	3,855	4,003
Temporarily Impaired 12 Months or more, Unrealized Losses	[1]	167	125
Temporarily Impaired Total, Fair Value	[1]	8,478	7,848
Temporarily Impaired Total, Unrealized Losses	[1]	$ 248	157
State and municipal securities
Temporarily Impaired Less than 12 months, Fair Value	[2]		0
Temporarily Impaired Less than 12 Months, Unrealized Losses	[2]		0
Temporarily Impaired 12 months or more, Fair Value	[2]		5
Temporarily Impaired 12 Months or more, Unrealized Losses	[2],[3]		0
Temporarily Impaired Total, Fair Value	[2]		5
Temporarily Impaired Total, Unrealized Losses	[2],[3]		0
Equity and other non-debt securities
Temporarily Impaired Less than 12 months, Fair Value	[2]		0
Temporarily Impaired Less than 12 Months, Unrealized Losses	[2]		0
Temporarily Impaired 12 months or more, Fair Value	[2]		44
Temporarily Impaired 12 Months or more, Unrealized Losses	[2]		2
Temporarily Impaired Total, Fair Value	[2]		44
Temporarily Impaired Total, Unrealized Losses	[2]		$ 2

[1]	Issued and/or guaranteed by U.S. government agencies or U.S. government-sponsored enterprises
[2]	Primarily auction-rate securities.
[3]	Unrealized losses less than $0.5 million.

Investment Securities (Contract

Investment Securities (Contractual Maturity Distribution Of Debt Securities) (Details) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017	[1]
Investment securities available-for-sale, Amortized Cost	$ 12,244	$ 11,061
Investment securities available-for-sale, Fair Value	11,971	$ 10,938
Debt securities
Available-for-sale, Within one year, Amortized Cost	100
Available-for-sale, After one year through five years, Amortized Cost	2,861
Available-for-sale, After five years through ten years, Amortized Cost	1,727
Available-for-sale, After ten years, Amortized Cost	7,557
Investment securities available-for-sale, Amortized Cost	12,245
Available-for-sale, Within one year, Fair Value	100
Available-for-sale, After one year through five years, Fair Value	2,823
Available-for-sale, After five years through ten years, Fair Value	1,709
Available-for-sale, After ten years, Fair Value	7,339
Investment securities available-for-sale, Fair Value	$ 11,971

[1]	Included auction-rate securities at amortized cost and fair value of $51 million and $49 million, respectively, as of December 31, 2017.

Credit Quality And Allowance 46

Credit Quality And Allowance For Credit Losses (Narrative) (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Retail loans secured by residential real estate in process of foreclosure		$ 0		$ 0
Commitments to lend additional funds to TDR borrowers		21		31
Foreclosed property	[1]	5		5
Principal Deferrals
Days past due defined as subsequent default			90 days
Balance		131	$ 152
Subsequent default during period		$ 0	$ 0
Interest Rate Reductions
Days past due defined as subsequent default		90 days	90 days
Balance		$ 17	$ 1
Subsequent default during period		$ 0	$ 0
AB Note Restructures
Days past due defined as subsequent default		90 days	90 days
Balance		$ 20	$ 48
Subsequent default during period		0	$ 0
Residential Real Estate
Foreclosed property		$ 4		$ 4

[1]	Included $4 million of foreclosed residential real estate properties at both March 31, 2018 and December 31, 2017.

Credit Quality And Allowance 47

Credit Quality And Allowance For Credit Losses (Aging Analysis Of Loans) (Details) - USD ($) $ in Millions		Mar. 31, 2018	Dec. 31, 2017
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		$ 237	$ 337
Nonaccrual loans		326	402
Current loans		48,677	48,434
Total loans		49,240	49,173
30 to 59 days past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		163	159
60 to 89 days past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		38	143
90 days or more past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		36	35
Business loans \| Commercial borrower
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		214	314
Nonaccrual loans		278	350
Current loans		44,231	43,967
Total loans		44,723	44,631
Business loans \| Commercial borrower \| 30 to 59 days past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		145	140
Business loans \| Commercial borrower \| 60 to 89 days past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		35	140
Business loans \| Commercial borrower \| 90 days or more past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		34	34
Business loans \| Commercial borrower \| Domestic loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		139	225
Nonaccrual loans		242	309
Current loans		30,528	30,526
Total loans		30,909	31,060
Business loans \| Commercial borrower \| Domestic loans \| 30 to 59 days past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		84	79
Business loans \| Commercial borrower \| Domestic loans \| 60 to 89 days past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		29	134
Business loans \| Commercial borrower \| Domestic loans \| 90 days or more past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		26	12
Business loans \| Commercial borrower \| International loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		14	13
Nonaccrual loans		4	6
Current loans		946	964
Total loans		964	983
Business loans \| Commercial borrower \| International loans \| 30 to 59 days past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		14	13
Business loans \| Commercial borrower \| International loans \| 60 to 89 days past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		0	0
Business loans \| Commercial borrower \| International loans \| 90 days or more past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		0	0
Business loans \| Real estate construction \| Commercial borrower \| Domestic loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		12	7
Nonaccrual loans		0	0
Current loans		3,102	2,954
Total loans		3,114	2,961
Business loans \| Real estate construction \| Commercial borrower \| Domestic loans \| 30 to 59 days past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		12	7
Business loans \| Real estate construction \| Commercial borrower \| Domestic loans \| 60 to 89 days past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		0	0
Business loans \| Real estate construction \| Commercial borrower \| Domestic loans \| 90 days or more past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		0	0
Business loans \| Real estate construction \| Commercial borrower \| Domestic loans \| Commercial Real Estate business line
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing	[1]	12	3
Nonaccrual loans	[1]	0	0
Current loans	[1]	2,746	2,627
Total loans	[1],[2]	2,758	2,630
Business loans \| Real estate construction \| Commercial borrower \| Domestic loans \| Commercial Real Estate business line \| 30 to 59 days past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing	[1]	12	3
Business loans \| Real estate construction \| Commercial borrower \| Domestic loans \| Commercial Real Estate business line \| 60 to 89 days past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing	[1]	0	0
Business loans \| Real estate construction \| Commercial borrower \| Domestic loans \| Commercial Real Estate business line \| 90 days or more past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing	[1]	0	0
Business loans \| Real estate construction \| Commercial borrower \| Domestic loans \| Other business lines
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing	[3]	0	4
Nonaccrual loans	[3]	0	0
Current loans	[3]	356	327
Total loans	[3],[4]	356	331
Business loans \| Real estate construction \| Commercial borrower \| Domestic loans \| Other business lines \| 30 to 59 days past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing	[3]	0	4
Business loans \| Real estate construction \| Commercial borrower \| Domestic loans \| Other business lines \| 60 to 89 days past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing	[3]	0	0
Business loans \| Real estate construction \| Commercial borrower \| Domestic loans \| Other business lines \| 90 days or more past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing	[3]	0	0
Business loans \| Real estate mortgage \| Commercial borrower \| Domestic loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		49	69
Nonaccrual loans		29	31
Current loans		9,194	9,059
Total loans		9,272	9,159
Business loans \| Real estate mortgage \| Commercial borrower \| Domestic loans \| 30 to 59 days past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		35	41
Business loans \| Real estate mortgage \| Commercial borrower \| Domestic loans \| 60 to 89 days past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		6	6
Business loans \| Real estate mortgage \| Commercial borrower \| Domestic loans \| 90 days or more past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		8	22
Business loans \| Real estate mortgage \| Commercial borrower \| Domestic loans \| Commercial Real Estate business line
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing	[1]	15	14
Nonaccrual loans	[1]	9	9
Current loans	[1]	1,882	1,808
Total loans	[1],[2]	1,906	1,831
Business loans \| Real estate mortgage \| Commercial borrower \| Domestic loans \| Commercial Real Estate business line \| 30 to 59 days past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing	[1]	15	14
Business loans \| Real estate mortgage \| Commercial borrower \| Domestic loans \| Commercial Real Estate business line \| 60 to 89 days past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing	[1]	0	0
Business loans \| Real estate mortgage \| Commercial borrower \| Domestic loans \| Commercial Real Estate business line \| 90 days or more past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing	[1]	0	0
Business loans \| Real estate mortgage \| Commercial borrower \| Domestic loans \| Other business lines
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing	[3]	34	55
Nonaccrual loans	[3]	20	22
Current loans	[3]	7,312	7,251
Total loans	[3],[4]	7,366	7,328
Business loans \| Real estate mortgage \| Commercial borrower \| Domestic loans \| Other business lines \| 30 to 59 days past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing	[3]	20	27
Business loans \| Real estate mortgage \| Commercial borrower \| Domestic loans \| Other business lines \| 60 to 89 days past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing	[3]	6	6
Business loans \| Real estate mortgage \| Commercial borrower \| Domestic loans \| Other business lines \| 90 days or more past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing	[3]	8	22
Business loans \| Lease financing \| Commercial borrower \| Domestic loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		0	0
Nonaccrual loans		3	4
Current loans		461	464
Total loans		464	468
Business loans \| Lease financing \| Commercial borrower \| Domestic loans \| 30 to 59 days past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		0	0
Business loans \| Lease financing \| Commercial borrower \| Domestic loans \| 60 to 89 days past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		0	0
Business loans \| Lease financing \| Commercial borrower \| Domestic loans \| 90 days or more past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		0	0
Retail loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		23	23
Nonaccrual loans		48	52
Current loans		4,446	4,467
Total loans		4,517	4,542
Retail loans \| 30 to 59 days past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		18	19
Retail loans \| 60 to 89 days past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		3	3
Retail loans \| 90 days or more past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		2	1
Retail loans \| Consumer borrower
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		11	11
Nonaccrual loans		19	21
Current loans		2,484	2,522
Total loans		2,514	2,554
Retail loans \| Consumer borrower \| 30 to 59 days past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		7	9
Retail loans \| Consumer borrower \| 60 to 89 days past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		2	1
Retail loans \| Consumer borrower \| 90 days or more past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		2	1
Retail loans \| Real estate mortgage
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		12	12
Nonaccrual loans		29	31
Current loans		1,962	1,945
Total loans		2,003	1,988
Retail loans \| Real estate mortgage \| 30 to 59 days past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		11	10
Retail loans \| Real estate mortgage \| 60 to 89 days past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		1	2
Retail loans \| Real estate mortgage \| 90 days or more past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		0	0
Retail loans \| Home equity \| Consumer borrower
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		9	6
Nonaccrual loans		19	21
Current loans		1,735	1,789
Total loans		1,763	1,816
Retail loans \| Home equity \| Consumer borrower \| 30 to 59 days past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		6	5
Retail loans \| Home equity \| Consumer borrower \| 60 to 89 days past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		2	1
Retail loans \| Home equity \| Consumer borrower \| 90 days or more past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		1	0
Retail loans \| Other consumer \| Consumer borrower
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		2	5
Nonaccrual loans		0	0
Current loans		749	733
Total loans		751	738
Retail loans \| Other consumer \| Consumer borrower \| 30 to 59 days past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		1	4
Retail loans \| Other consumer \| Consumer borrower \| 60 to 89 days past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		0	0
Retail loans \| Other consumer \| Consumer borrower \| 90 days or more past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		$ 1	$ 1

[1]	Primarily loans to real estate developers.
[2]	Primarily loans to real estate developers.
[3]	Primarily loans secured by owner-occupied real estate.
[4]	Primarily loans secured by owner-occupied real estate.

Credit Quality And Allowance 48

Credit Quality And Allowance For Credit Losses (Loans By Credit Quality Indicator) (Details) - USD ($) $ in Millions		Mar. 31, 2018	Dec. 31, 2017
Financing Receivable, Recorded Investment [Line Items]
Total loans		$ 49,240	$ 49,173
Pass
Financing Receivable, Recorded Investment [Line Items]
Total loans	[1]	47,120	46,942
Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total loans	[2]	717	768
Substandard
Financing Receivable, Recorded Investment [Line Items]
Total loans	[3]	1,077	1,061
Nonaccrual
Financing Receivable, Recorded Investment [Line Items]
Total loans	[4]	326	402
Business loans \| Commercial borrower
Financing Receivable, Recorded Investment [Line Items]
Total loans		44,723	44,631
Business loans \| Commercial borrower \| Pass
Financing Receivable, Recorded Investment [Line Items]
Total loans	[1]	42,664	42,464
Business loans \| Commercial borrower \| Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total loans	[2]	715	764
Business loans \| Commercial borrower \| Substandard
Financing Receivable, Recorded Investment [Line Items]
Total loans	[3]	1,066	1,053
Business loans \| Commercial borrower \| Nonaccrual
Financing Receivable, Recorded Investment [Line Items]
Total loans	[4]	278	350
Business loans \| Commercial borrower \| Domestic loans
Financing Receivable, Recorded Investment [Line Items]
Total loans		30,909	31,060
Business loans \| Commercial borrower \| Domestic loans \| Pass
Financing Receivable, Recorded Investment [Line Items]
Total loans	[1]	29,195	29,263
Business loans \| Commercial borrower \| Domestic loans \| Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total loans	[2]	579	591
Business loans \| Commercial borrower \| Domestic loans \| Substandard
Financing Receivable, Recorded Investment [Line Items]
Total loans	[3]	893	897
Business loans \| Commercial borrower \| Domestic loans \| Nonaccrual
Financing Receivable, Recorded Investment [Line Items]
Total loans	[4]	242	309
Business loans \| Commercial borrower \| International loans
Financing Receivable, Recorded Investment [Line Items]
Total loans		964	983
Business loans \| Commercial borrower \| International loans \| Pass
Financing Receivable, Recorded Investment [Line Items]
Total loans	[1]	926	946
Business loans \| Commercial borrower \| International loans \| Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total loans	[2]	5	11
Business loans \| Commercial borrower \| International loans \| Substandard
Financing Receivable, Recorded Investment [Line Items]
Total loans	[3]	29	20
Business loans \| Commercial borrower \| International loans \| Nonaccrual
Financing Receivable, Recorded Investment [Line Items]
Total loans	[4]	4	6
Business loans \| Real estate construction \| Commercial borrower \| Domestic loans
Financing Receivable, Recorded Investment [Line Items]
Total loans		3,114	2,961
Business loans \| Real estate construction \| Commercial borrower \| Domestic loans \| Pass
Financing Receivable, Recorded Investment [Line Items]
Total loans	[1]	3,110	2,957
Business loans \| Real estate construction \| Commercial borrower \| Domestic loans \| Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total loans	[2]	4	4
Business loans \| Real estate construction \| Commercial borrower \| Domestic loans \| Substandard
Financing Receivable, Recorded Investment [Line Items]
Total loans	[3]	0	0
Business loans \| Real estate construction \| Commercial borrower \| Domestic loans \| Nonaccrual
Financing Receivable, Recorded Investment [Line Items]
Total loans	[4]	0	0
Business loans \| Real estate construction \| Commercial borrower \| Domestic loans \| Commercial Real Estate business line
Financing Receivable, Recorded Investment [Line Items]
Total loans	[5],[6]	2,758	2,630
Business loans \| Real estate construction \| Commercial borrower \| Domestic loans \| Commercial Real Estate business line \| Pass
Financing Receivable, Recorded Investment [Line Items]
Total loans	[1],[5]	2,758	2,630
Business loans \| Real estate construction \| Commercial borrower \| Domestic loans \| Commercial Real Estate business line \| Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total loans	[2],[5]	0	0
Business loans \| Real estate construction \| Commercial borrower \| Domestic loans \| Commercial Real Estate business line \| Substandard
Financing Receivable, Recorded Investment [Line Items]
Total loans	[3],[5]	0	0
Business loans \| Real estate construction \| Commercial borrower \| Domestic loans \| Commercial Real Estate business line \| Nonaccrual
Financing Receivable, Recorded Investment [Line Items]
Total loans	[4],[5]	0	0
Business loans \| Real estate construction \| Commercial borrower \| Domestic loans \| Other business lines
Financing Receivable, Recorded Investment [Line Items]
Total loans	[7],[8]	356	331
Business loans \| Real estate construction \| Commercial borrower \| Domestic loans \| Other business lines \| Pass
Financing Receivable, Recorded Investment [Line Items]
Total loans	[1],[7]	352	327
Business loans \| Real estate construction \| Commercial borrower \| Domestic loans \| Other business lines \| Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total loans	[2],[7]	4	4
Business loans \| Real estate construction \| Commercial borrower \| Domestic loans \| Other business lines \| Substandard
Financing Receivable, Recorded Investment [Line Items]
Total loans	[3],[7]	0	0
Business loans \| Real estate construction \| Commercial borrower \| Domestic loans \| Other business lines \| Nonaccrual
Financing Receivable, Recorded Investment [Line Items]
Total loans	[4],[7]	0	0
Business loans \| Real estate mortgage \| Commercial borrower \| Domestic loans
Financing Receivable, Recorded Investment [Line Items]
Total loans		9,272	9,159
Business loans \| Real estate mortgage \| Commercial borrower \| Domestic loans \| Pass
Financing Receivable, Recorded Investment [Line Items]
Total loans	[1]	8,980	8,858
Business loans \| Real estate mortgage \| Commercial borrower \| Domestic loans \| Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total loans	[2]	122	135
Business loans \| Real estate mortgage \| Commercial borrower \| Domestic loans \| Substandard
Financing Receivable, Recorded Investment [Line Items]
Total loans	[3]	141	135
Business loans \| Real estate mortgage \| Commercial borrower \| Domestic loans \| Nonaccrual
Financing Receivable, Recorded Investment [Line Items]
Total loans	[4]	29	31
Business loans \| Real estate mortgage \| Commercial borrower \| Domestic loans \| Commercial Real Estate business line
Financing Receivable, Recorded Investment [Line Items]
Total loans	[5],[6]	1,906	1,831
Business loans \| Real estate mortgage \| Commercial borrower \| Domestic loans \| Commercial Real Estate business line \| Pass
Financing Receivable, Recorded Investment [Line Items]
Total loans	[1],[5]	1,836	1,759
Business loans \| Real estate mortgage \| Commercial borrower \| Domestic loans \| Commercial Real Estate business line \| Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total loans	[2],[5]	15	20
Business loans \| Real estate mortgage \| Commercial borrower \| Domestic loans \| Commercial Real Estate business line \| Substandard
Financing Receivable, Recorded Investment [Line Items]
Total loans	[3],[5]	46	43
Business loans \| Real estate mortgage \| Commercial borrower \| Domestic loans \| Commercial Real Estate business line \| Nonaccrual
Financing Receivable, Recorded Investment [Line Items]
Total loans	[4],[5]	9	9
Business loans \| Real estate mortgage \| Commercial borrower \| Domestic loans \| Other business lines
Financing Receivable, Recorded Investment [Line Items]
Total loans	[7],[8]	7,366	7,328
Business loans \| Real estate mortgage \| Commercial borrower \| Domestic loans \| Other business lines \| Pass
Financing Receivable, Recorded Investment [Line Items]
Total loans	[1],[7]	7,144	7,099
Business loans \| Real estate mortgage \| Commercial borrower \| Domestic loans \| Other business lines \| Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total loans	[2],[7]	107	115
Business loans \| Real estate mortgage \| Commercial borrower \| Domestic loans \| Other business lines \| Substandard
Financing Receivable, Recorded Investment [Line Items]
Total loans	[3],[7]	95	92
Business loans \| Real estate mortgage \| Commercial borrower \| Domestic loans \| Other business lines \| Nonaccrual
Financing Receivable, Recorded Investment [Line Items]
Total loans	[4],[7]	20	22
Business loans \| Lease financing \| Commercial borrower \| Domestic loans
Financing Receivable, Recorded Investment [Line Items]
Total loans		464	468
Business loans \| Lease financing \| Commercial borrower \| Domestic loans \| Pass
Financing Receivable, Recorded Investment [Line Items]
Total loans	[1]	453	440
Business loans \| Lease financing \| Commercial borrower \| Domestic loans \| Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total loans	[2]	5	23
Business loans \| Lease financing \| Commercial borrower \| Domestic loans \| Substandard
Financing Receivable, Recorded Investment [Line Items]
Total loans	[3]	3	1
Business loans \| Lease financing \| Commercial borrower \| Domestic loans \| Nonaccrual
Financing Receivable, Recorded Investment [Line Items]
Total loans	[4]	3	4
Retail loans
Financing Receivable, Recorded Investment [Line Items]
Total loans		4,517	4,542
Retail loans \| Pass
Financing Receivable, Recorded Investment [Line Items]
Total loans	[1]	4,456	4,478
Retail loans \| Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total loans	[2]	2	4
Retail loans \| Substandard
Financing Receivable, Recorded Investment [Line Items]
Total loans	[3]	11	8
Retail loans \| Nonaccrual
Financing Receivable, Recorded Investment [Line Items]
Total loans	[4]	48	52
Retail loans \| Consumer borrower
Financing Receivable, Recorded Investment [Line Items]
Total loans		2,514	2,554
Retail loans \| Consumer borrower \| Pass
Financing Receivable, Recorded Investment [Line Items]
Total loans	[1]	2,483	2,523
Retail loans \| Consumer borrower \| Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total loans	[2]	1	2
Retail loans \| Consumer borrower \| Substandard
Financing Receivable, Recorded Investment [Line Items]
Total loans	[3]	11	8
Retail loans \| Consumer borrower \| Nonaccrual
Financing Receivable, Recorded Investment [Line Items]
Total loans	[4]	19	21
Retail loans \| Real estate mortgage
Financing Receivable, Recorded Investment [Line Items]
Total loans		2,003	1,988
Retail loans \| Real estate mortgage \| Pass
Financing Receivable, Recorded Investment [Line Items]
Total loans	[1]	1,973	1,955
Retail loans \| Real estate mortgage \| Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total loans	[2]	1	2
Retail loans \| Real estate mortgage \| Substandard
Financing Receivable, Recorded Investment [Line Items]
Total loans	[3]	0	0
Retail loans \| Real estate mortgage \| Nonaccrual
Financing Receivable, Recorded Investment [Line Items]
Total loans	[4]	29	31
Retail loans \| Home equity \| Consumer borrower
Financing Receivable, Recorded Investment [Line Items]
Total loans		1,763	1,816
Retail loans \| Home equity \| Consumer borrower \| Pass
Financing Receivable, Recorded Investment [Line Items]
Total loans	[1]	1,733	1,786
Retail loans \| Home equity \| Consumer borrower \| Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total loans	[2]	0	1
Retail loans \| Home equity \| Consumer borrower \| Substandard
Financing Receivable, Recorded Investment [Line Items]
Total loans	[3]	11	8
Retail loans \| Home equity \| Consumer borrower \| Nonaccrual
Financing Receivable, Recorded Investment [Line Items]
Total loans	[4]	19	21
Retail loans \| Other consumer \| Consumer borrower
Financing Receivable, Recorded Investment [Line Items]
Total loans		751	738
Retail loans \| Other consumer \| Consumer borrower \| Pass
Financing Receivable, Recorded Investment [Line Items]
Total loans	[1]	750	737
Retail loans \| Other consumer \| Consumer borrower \| Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total loans	[2]	1	1
Retail loans \| Other consumer \| Consumer borrower \| Substandard
Financing Receivable, Recorded Investment [Line Items]
Total loans	[3]	0	0
Retail loans \| Other consumer \| Consumer borrower \| Nonaccrual
Financing Receivable, Recorded Investment [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 - on pages F-51 and F-52 in the Corporation's 2017 Annual Report. 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 to real estate developers.
[7]	Primarily loans secured by owner-occupied real estate.
[8]	Primarily loans secured by owner-occupied real estate.

Credit Quality And Allowance 49

Credit Quality And Allowance For Credit Losses (Schedule Of Nonaccrual, Reduced-Rate Loans And Foreclosed Property) (Details) - USD ($) $ in Millions		Mar. 31, 2018	Dec. 31, 2017
Nonaccrual loans		$ 326	$ 402
Reduced-rate loans	[1]	8	8
Total nonperforming loans		334	410
Foreclosed property	[2]	5	5
Total nonperforming assets		339	415
Residential Real Estate
Foreclosed property		4	4
Business loans
Reduced-rate loans		0	0
Retail loans
Nonaccrual loans		48	52
Reduced-rate loans		$ 8	$ 8

[1]	There were no reduced-rate business loans at both March 31, 2018 and December 31, 2017. Reduced-rate retail loans were $8 million at both March 31, 2018 and December 31, 2017.
[2]	Included $4 million of foreclosed residential real estate properties at both March 31, 2018 and December 31, 2017.

Credit Quality And Allowance 50

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
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017
Financing Receivable, Allowance for Credit Losses [Line Items]
Provision for loan losses	$ 12	$ 16
Total loans			$ 49,240	$ 49,173
Financing Receivable
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance at beginning of period	712	730
Loan charge-offs	(37)	(44)
Recoveries on loans previously charged-off	9	11
Net loan charge-offs (recoveries)	(28)	(33)
Provision for loan losses	14	11
Balance at end of period	698	708
As a percentage of total loans			1.42%		1.47%
Allowance for loan losses individually evaluated for impairment			$ 42		$ 89
Allowance for loan losses collectively evaluated for impairment			656		619
Total allowance for loan losses	712	730	698	712	708
Loans individually evaluated for impairment			415		576
Loans collectively evaluated for impairment			48,825		47,727
Total loans			$ 49,240		$ 48,303
Business loans \| Financing Receivable
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance at beginning of period	661	682
Loan charge-offs	(36)	(42)
Recoveries on loans previously charged-off	8	9
Net loan charge-offs (recoveries)	(28)	(33)
Provision for loan losses	20	12
Balance at end of period	653	661
As a percentage of total loans			1.46%		1.51%
Allowance for loan losses individually evaluated for impairment			$ 42		$ 87
Allowance for loan losses collectively evaluated for impairment			611		574
Total allowance for loan losses	661	682	653	661	661
Loans individually evaluated for impairment			384		535
Loans collectively evaluated for impairment			44,339		43,287
Total loans			44,723		$ 43,822
Retail loans
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans			$ 4,517	4,542
Retail loans \| Financing Receivable
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance at beginning of period	51	48
Loan charge-offs	(1)	(2)
Recoveries on loans previously charged-off	1	2
Net loan charge-offs (recoveries)	0	0
Provision for loan losses	(6)	(1)
Balance at end of period	45	47
As a percentage of total loans			0.99%		1.05%
Allowance for loan losses individually evaluated for impairment			$ 0		$ 2
Allowance for loan losses collectively evaluated for impairment			45		45
Total allowance for loan losses	$ 51	$ 48	45	$ 51	47
Loans individually evaluated for impairment			31		41
Loans collectively evaluated for impairment			4,486		4,440
Total loans			$ 4,517		$ 4,481

Credit Quality And Allowance 51

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
	Mar. 31, 2018	Mar. 31, 2017
Financing Receivable, Allowance for Credit Losses [Line Items]
Provision for credit losses	$ 12	$ 16
Lending-related commitments
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance at beginning of period	42	41
Provision for credit losses	(2)	5
Balance at end of period	$ 40	$ 46

Credit Quality And Allowance 52

Credit Quality And Allowance For Credit Losses (Individually Evaluated Impaired Loans) (Details) - USD ($) $ in Millions		Mar. 31, 2018	Dec. 31, 2017
Financing Receivable, Impaired [Line Items]
Recorded investment in impaired loans with no related allowance		$ 227	$ 173
Recorded investment in impaired loans with related allowance		188	304
Recorded investment total impaired loans		415	477
Unpaid principal balance		525	593
Related allowance for loan losses		42	67
Business loans \| Commercial borrower
Financing Receivable, Impaired [Line Items]
Recorded investment in impaired loans with no related allowance		204	147
Recorded investment in impaired loans with related allowance		180	296
Recorded investment total impaired loans		384	443
Unpaid principal balance		490	555
Related allowance for loan losses		42	67
Business loans \| Commercial borrower \| Domestic loans
Financing Receivable, Impaired [Line Items]
Recorded investment in impaired loans with no related allowance		159	105
Recorded investment in impaired loans with related allowance		156	267
Recorded investment total impaired loans		315	372
Unpaid principal balance		403	460
Related allowance for loan losses		39	63
Business loans \| Commercial borrower \| International loans
Financing Receivable, Impaired [Line Items]
Recorded investment in impaired loans with no related allowance		3	0
Recorded investment in impaired loans with related allowance		1	6
Recorded investment total impaired loans		4	6
Unpaid principal balance		9	17
Related allowance for loan losses		0	1
Business loans \| Real estate mortgage \| Commercial borrower \| Domestic loans
Financing Receivable, Impaired [Line Items]
Recorded investment in impaired loans with no related allowance		42	42
Recorded investment in impaired loans with related allowance		23	23
Recorded investment total impaired loans		65	65
Unpaid principal balance		78	78
Related allowance for loan losses		3	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]	1	1
Recorded investment total impaired loans	[1]	40	40
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]	3	3
Recorded investment in impaired loans with related allowance	[2]	22	22
Recorded investment total impaired loans	[2]	25	25
Unpaid principal balance	[2]	29	29
Related allowance for loan losses	[2]	3	3
Retail loans
Financing Receivable, Impaired [Line Items]
Recorded investment in impaired loans with no related allowance	[3]	23	26
Recorded investment in impaired loans with related allowance	[3]	8	8
Recorded investment total impaired loans	[3]	31	34
Unpaid principal balance	[3]	35	38
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	12
Recorded investment in impaired loans with related allowance		0	0
Recorded investment total impaired loans		12	12
Unpaid principal balance		15	16
Related allowance for loan losses		0	0
Retail loans \| Real estate mortgage
Financing Receivable, Impaired [Line Items]
Recorded investment in impaired loans with no related allowance		11	14
Recorded investment in impaired loans with related allowance		8	8
Recorded investment total impaired loans		19	22
Unpaid principal balance		20	22
Related allowance for loan losses		0	0
Retail loans \| Home equity \| Consumer borrower
Financing Receivable, Impaired [Line Items]
Recorded investment in impaired loans with no related allowance		11	11
Recorded investment in impaired loans with related allowance		0	0
Recorded investment total impaired loans		11	11
Unpaid principal balance		13	14
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	1
Recorded investment in impaired loans with related allowance		0	0
Recorded investment total impaired loans		1	1
Unpaid principal balance		2	2
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 53

Credit Quality And Allowance For Credit Losses (Average Individually Evaluated Impaired Loans And Related Interest Recognized) (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2018	Mar. 31, 2017
Financing Receivable, Impaired [Line Items]
Individually Evaluated Impaired Loans Average Balance for the Period		$ 446	$ 595
Individually Evaluated Impaired Loans Interest Income Recognized for the Period		2	2
Business loans \| Commercial borrower
Financing Receivable, Impaired [Line Items]
Individually Evaluated Impaired Loans Average Balance for the Period		414	550
Individually Evaluated Impaired Loans Interest Income Recognized for the Period		2	2
Business loans \| Commercial borrower \| Domestic loans
Financing Receivable, Impaired [Line Items]
Individually Evaluated Impaired Loans Average Balance for the Period		344	498
Individually Evaluated Impaired Loans Interest Income Recognized for the Period		1	2
Business loans \| Commercial borrower \| International loans
Financing Receivable, Impaired [Line Items]
Individually Evaluated Impaired Loans Average Balance for the Period		5	11
Individually Evaluated Impaired Loans Interest Income Recognized for the Period		0	0
Business loans \| Real estate mortgage \| Commercial borrower \| Domestic loans
Financing Receivable, Impaired [Line Items]
Individually Evaluated Impaired Loans Average Balance for the Period		65	41
Individually Evaluated Impaired Loans Interest Income Recognized for the Period		1	0
Business loans \| Real estate mortgage \| Commercial borrower \| Domestic loans \| Commercial Real Estate business line
Financing Receivable, Impaired [Line Items]
Individually Evaluated Impaired Loans Average Balance for the Period	[1]	40	7
Individually Evaluated Impaired Loans Interest Income Recognized for the Period	[1]	1	0
Business loans \| Real estate mortgage \| Commercial borrower \| Domestic loans \| Other business lines
Financing Receivable, Impaired [Line Items]
Individually Evaluated Impaired Loans Average Balance for the Period	[2]	25	34
Individually Evaluated Impaired Loans Interest Income Recognized for the Period	[2]	0	0
Retail loans
Financing Receivable, Impaired [Line Items]
Individually Evaluated Impaired Loans Average Balance for the Period		32	45
Individually Evaluated Impaired Loans Interest Income Recognized for the Period		0	0
Retail loans \| Consumer borrower
Financing Receivable, Impaired [Line Items]
Individually Evaluated Impaired Loans Average Balance for the Period		12	18
Individually Evaluated Impaired Loans Interest Income Recognized for the Period		0	0
Retail loans \| Real estate mortgage
Financing Receivable, Impaired [Line Items]
Individually Evaluated Impaired Loans Average Balance for the Period		20	27
Individually Evaluated Impaired Loans Interest Income Recognized for the Period		0	0
Retail loans \| Home equity \| Consumer borrower
Financing Receivable, Impaired [Line Items]
Individually Evaluated Impaired Loans Average Balance for the Period		11	14
Individually Evaluated Impaired Loans Interest Income Recognized for the Period		0	0
Retail loans \| Other consumer \| Consumer borrower
Financing Receivable, Impaired [Line Items]
Individually Evaluated Impaired Loans Average Balance for the Period		1	4
Individually Evaluated Impaired Loans Interest Income Recognized for the Period		$ 0	$ 0

[1]	Primarily loans to real estate developers.
[2]	Primarily loans secured by owner-occupied real estate.

Credit Quality And Allowance 54

Credit Quality And Allowance For Credit Losses (Troubled Debt Restructurings By Type Of Modification) (Details) - Principal Deferrals - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2018	Mar. 31, 2017
Financing Receivable, Modifications [Line Items]
Recorded balance of troubled debt restructuring modified during the period	[1]	$ 30	$ 86
Minimum period loan terms were extended		90 days
Business loans \| Commercial borrower
Financing Receivable, Modifications [Line Items]
Recorded balance of troubled debt restructuring modified during the period	[1]	$ 29	85
Business loans \| Commercial borrower \| Domestic loans
Financing Receivable, Modifications [Line Items]
Recorded balance of troubled debt restructuring modified during the period	[1]	28	80
Business loans \| Real estate mortgage \| Commercial borrower \| Domestic loans \| Other business lines
Financing Receivable, Modifications [Line Items]
Recorded balance of troubled debt restructuring modified during the period	[1],[2]	1	5
Retail loans \| Home equity \| Consumer borrower
Financing Receivable, Modifications [Line Items]
Recorded balance of troubled debt restructuring modified during the period	[1],[3]	$ 1	$ 1

[1]	Primarily represents loan balances where terms were extended 90 days or more at or above contractual interest rates.
[2]	Primarily loans to secured by owner-occupied real estate.
[3]	Includes bankruptcy loans for which the court has discharged the borrower's obligation and the borrower has not reaffirmed the debt.

Credit Quality And Allowance 55

Credit Quality And Allowance For Credit Losses Credit Quality And Allowance For Credit Losses (Troubled Debt Restructuring Subsequent Default) (Details) - Principal Deferrals - USD ($) $ in Millions		Mar. 31, 2018	Mar. 31, 2017
Financing Receivable, Modifications [Line Items]
Balance		$ 131	$ 152
Business loans \| Commercial borrower
Financing Receivable, Modifications [Line Items]
Balance		129	150
Business loans \| Commercial borrower \| Domestic loans
Financing Receivable, Modifications [Line Items]
Balance		90	141
Business loans \| Real estate mortgage \| Commercial borrower \| Domestic loans
Financing Receivable, Modifications [Line Items]
Balance		39	9
Business loans \| Real estate mortgage \| Commercial borrower \| Domestic loans \| Commercial Real Estate business line
Financing Receivable, Modifications [Line Items]
Balance	[1]	37	0
Business loans \| Real estate mortgage \| Commercial borrower \| Domestic loans \| Other business lines
Financing Receivable, Modifications [Line Items]
Balance		2	9
Retail loans \| Home equity \| Consumer borrower
Financing Receivable, Modifications [Line Items]
Balance		$ 2	$ 2

[1]	a)Primarily loans secured by owner-occupied real estate.

Derivative And Credit-Related56

Derivative And Credit-Related Financial Instruments (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Effects of fair value hedging on the Consolidated Statements o Comprehensive Income [Line Items]
Fair value of securities pledged as collateral for derivative liabilities	$ 5
Cash received as collateral for derivative assets	8
Fair value of securities received as collateral for derivative assets	11
Cash posted as collateral for derivative liabilities	63
Aggregate fair value of all derivative instruments with credit-risk contingent features that were in a liability position	0
Gain (loss) on foreign currency derivatives used as economic hedges	0	$ 0
Net gain on open foreign currency positions	0	$ 0
Allowance for credit losses on lending-related commitments	40		$ 42
Allowance for credit losses on lending-related commitments, amount related to unused commitments to extend credit	$ 26		27
Final year of expiration for outstanding letters of credit	2,028
Risk participation agreements covering standby and commercial letters of credit	$ 123		127
Standby and commercial letters of credit	3,300		3,300
Carrying value of standby and commercial letters of credit included in accrued expenses and other liabilities	42		40
Deferred fees on standby and commercial letters of credit included in accrued expenses and other liabilities	28		25
Allowance for credit losses on lending-related commitments, amount related to standby and commercial letters of credit	14		15
Notional amount of derivative credit risk participation agreements	540		549
Maximum estimated exposure to credit risk participation agreements assuming 100% default	$ 0		$ 0
Weighted average remaining maturity of credit risk participation agreements, in years	2 years 4 months 6 days

Derivative And Credit-Related57

Derivative And Credit-Related Financial Instruments (Schedule Of Derivative Instruments) (Details) - USD ($) $ in Millions		Mar. 31, 2018	Dec. 31, 2017
Derivatives, Fair Value [Line Items]
Notional/Contract Amount	[1]	$ 20,041	$ 20,545
Fair Value of Gross Derivative Assets		177	192
Fair Value of Gross Derivative Liabilities		236	190
Derivative assets, Netting adjustment - Offsetting derivative liabilities		(49)	(49)
Derivative liabilities, Netting adjustment - Offsetting derivative assets		(49)	(49)
Derivative assets, Netting adjustment - Cash collateral received		(5)	(1)
Derivative liabilities, Netting adjustment, Cash collateral posted		(62)	(39)
Net derivative assets included in the consolidated balance sheets	[2]	123	142
Net derivative liabilities included in the consolidated balance sheets	[2]	125	102
Derivative asset, securities pledged as collateral		(5)	(3)
Derivative liability, securities pledged as collateral		(11)	(24)
Net derivative assets after deducting amounts not offset in the consolidated balance sheets		118	139
Net derivative liabilities after deducting amounts not offset in the consolidated balance sheets		114	78
Credit valuation adjustments for counterparty credit risk		3	4
Risk management purposes
Derivatives, Fair Value [Line Items]
Notional/Contract Amount	[1]	2,422	2,425
Fair Value of Gross Derivative Assets		0	0
Fair Value of Gross Derivative Liabilities		3	4
Risk management purposes \| Derivatives designated as hedging instruments \| Fair Value Hedging \| Interest rate swap
Derivatives, Fair Value [Line Items]
Notional/Contract Amount	[1]	1,775	1,775
Fair Value of Gross Derivative Assets		0	0
Fair Value of Gross Derivative Liabilities		3	2
Risk management purposes \| Derivatives used as economic hedges \| Foreign exchange spot, forwards and swaps
Derivatives, Fair Value [Line Items]
Notional/Contract Amount	[1]	647	650
Fair Value of Gross Derivative Assets		0	0
Fair Value of Gross Derivative Liabilities		0	2
Customer-initiated and other activities
Derivatives, Fair Value [Line Items]
Notional/Contract Amount	[1]	17,619	18,120
Fair Value of Gross Derivative Assets		177	192
Fair Value of Gross Derivative Liabilities		233	186
Customer-initiated and other activities \| Interest rate contracts
Derivatives, Fair Value [Line Items]
Notional/Contract Amount	[1]	13,618	14,389
Fair Value of Gross Derivative Assets		33	57
Fair Value of Gross Derivative Liabilities		95	57
Customer-initiated and other activities \| Interest rate caps and floors written
Derivatives, Fair Value [Line Items]
Notional/Contract Amount	[1]	582	635
Fair Value of Gross Derivative Assets		0	0
Fair Value of Gross Derivative Liabilities		2	0
Customer-initiated and other activities \| Interest rate caps and floors purchased
Derivatives, Fair Value [Line Items]
Notional/Contract Amount	[1]	582	635
Fair Value of Gross Derivative Assets		2	0
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]	12,454	13,119
Fair Value of Gross Derivative Assets		31	57
Fair Value of Gross Derivative Liabilities		93	57
Customer-initiated and other activities \| Energy contracts
Derivatives, Fair Value [Line Items]
Notional/Contract Amount	[1]	2,025	1,847
Fair Value of Gross Derivative Assets		107	93
Fair Value of Gross Derivative Liabilities		106	91
Customer-initiated and other activities \| Energy caps and floors written
Derivatives, Fair Value [Line Items]
Notional/Contract Amount	[1]	135	164
Fair Value of Gross Derivative Assets		0	0
Fair Value of Gross Derivative Liabilities		11	11
Customer-initiated and other activities \| Energy caps and floors purchased
Derivatives, Fair Value [Line Items]
Notional/Contract Amount	[1]	135	164
Fair Value of Gross Derivative Assets		11	11
Fair Value of Gross Derivative Liabilities		0	0
Customer-initiated and other activities \| Energy swaps
Derivatives, Fair Value [Line Items]
Notional/Contract Amount	[1]	1,755	1,519
Fair Value of Gross Derivative Assets		96	82
Fair Value of Gross Derivative Liabilities		95	80
Customer-initiated and other activities \| Foreign exchange spot, options and swaps
Derivatives, Fair Value [Line Items]
Notional/Contract Amount	[1]	1,976	1,884
Fair Value of Gross Derivative Assets		37	42
Fair Value of Gross Derivative Liabilities		$ 32	$ 38

[1]	Notional or contractual amounts, which represent the extent of involvement in the derivatives market, are used to determine the contractual cash flows required in accordance with the terms of the agreement. These amounts are typically not exchanged, significantly exceed amounts subject to credit or market risk and are not reflected in the Consolidated Balance Sheets.
[2]	Net derivative assets are included in accrued income and other assets and net derivative liabilities are included in accrued expenses and other liabilities on the Consolidated Balance Sheets. Included in the fair value of net derivative assets and net derivative liabilities are credit valuation adjustments reflecting counterparty credit risk and credit risk of the Corporation. The fair value of net derivative assets included credit valuation adjustments for counterparty credit risk of $3 million and $4 million at March 31, 2018 and December 31, 2017, respectively.

Derivative And Credit-Related58

Derivative And Credit-Related Financial Instruments Derivative and Credit-Related Financial Instruments (Schedule of the Effects of Fair Value Hedging on the Consolidated Statements of Comprehensive Income (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2018	Mar. 31, 2017
Total interest on medium- and long-term debt	[1]	$ 25	$ 17
Swaps - fair value - receive fixed/pay floating \| Risk management purposes \| Interest rate swap
Interest rate contract: Hedge items interest expense		15	22
Interest rate contracts: Derivatives designated as hedging instruments net interest income		$ (3)	$ (10)

[1]	Includes the effects of hedging.

Derivative And Credit-Related59

Derivative And Credit-Related Financial Instruments (Schedule Of Weighted Average Maturity And Interest Rates On Risk Management Interest Rate Swaps) (Details) - USD ($) $ in Millions		3 Months Ended	12 Months Ended
		Mar. 31, 2018	Dec. 31, 2017
Derivative assets credit valuation adjustments		$ 3	$ 4
Notional Amount	[1]	20,041	20,545
Risk management purposes
Notional Amount	[1]	2,422	2,425
Medium- and long-term debt \| Swaps - fair value - receive fixed/pay floating \| Risk management purposes \| Interest rate swap
Notional Amount		$ 1,775	$ 1,775
Weighted Average Remaining Maturity		4 years 4 months 8 days	4 years 7 months 17 days
Weighted Average Receive Rate		3.26%	3.26%
Weighted Average Pay Rate	[2]	2.59%	2.35%

[1]	Notional or contractual amounts, which represent the extent of involvement in the derivatives market, are used to determine the contractual cash flows required in accordance with the terms of the agreement. These amounts are typically not exchanged, significantly exceed amounts subject to credit or market risk and are not reflected in the Consolidated Balance Sheets.
[2]	{F\|ahBzfndlYmZpbGluZ3MtaHJkcmoLEgZYTUxEb2MiXlhCUkxEb2NHZW5JbmZvOjViYzVkNGZjM2M3NjQyZDBiNjc1YmE1NDY2ZmUxY2Y4fFRleHRTZWxlY3Rpb246RUNDNjNBRkVFRUNGNTAyMUI2QjcwQzQ3RUM4RjY1MzIM}

Derivative And Credit-Related60

Derivative And Credit-Related Financial Instruments (Schedule Of Net Gains Recognized In Income On Customer-Initiated Derivatives) (Details) - Customer-initiated and other activities - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Derivative Instruments, Gain (Loss) [Line Items]
Net derivative gain recognized in income	$ 16	$ 17
Interest rate contracts \| Other noninterest income
Derivative Instruments, Gain (Loss) [Line Items]
Net derivative gain recognized in income	4	6
Foreign exchange contracts \| Foreign exchange income
Derivative Instruments, Gain (Loss) [Line Items]
Net derivative gain recognized in income	$ 12	$ 11

Derivative And Credit-Related61

Derivative And Credit-Related Financial Instruments (Schedule Of Financial Instruments With Off-Balance Sheet Credit Risk) (Details) - Maximum - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Unused Commitments to Extend Credit
Loss contingency, estimate of possible loss, maximum	$ (25,007)	$ (25,469)
Commercial And Other \| Unused Commitments to Extend Credit
Loss contingency, estimate of possible loss, maximum	(22,169)	(22,636)
Bankcard, Revolving Check Credit And Home Equity Loan Commitments \| Unused Commitments to Extend Credit
Loss contingency, estimate of possible loss, maximum	(2,838)	(2,833)
Standby Letters Of Credit
Loss contingency, estimate of possible loss, maximum	(3,245)	(3,228)
Commercial Letters Of Credit
Loss contingency, estimate of possible loss, maximum	$ (37)	$ (39)

Derivative And Credit-Related62

Derivative And Credit-Related Financial Instruments (Summary Of Internally Classified Watch List Letters Of Credit) (Details) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Total criticized standby and commercial letters of credit	$ 77	$ 88
As a percentage of total outstanding standby and commercial letters of credit	2.40%	2.70%

Variable Interest Entities (V63

Variable Interest Entities (VIEs) (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Variable Interest Entity
Unfunded commitments to fund tax credit entities	$ 165
Amount of financial or other support not contractually required provided by the Corporation to VIEs	0	$ 0
Low Income Housing Tax Credit Entities
Variable Interest Entity
Exposure to loss as a result of involvement with VIEs	426
Other Tax Credit Entities
Variable Interest Entity
Exposure to loss as a result of involvement with VIEs	$ 7

Variable Interest Entities (V64

Variable Interest Entities (VIEs) (Impact Of VIEs On The Consolidated Statements Of Comprehensive Income) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Variable Interest Entity
Other noninterest income	$ 23	$ 29
Provision for income taxes	54	66
Variable Interest Entity
Variable Interest Entity
Other noninterest income	1	1
Provision for income taxes, amortization of LIHTC investments	15	16
Provision for income taxes	(3)	(5)
Low income housing tax credits \| Variable Interest Entity
Variable Interest Entity
Provision for income taxes, affordable housing tax credits and other tax benefits	(15)	(15)
Other tax benefits related to tax credit entities \| Variable Interest Entity
Variable Interest Entity
Provision for income taxes, affordable housing tax credits and other tax benefits	$ (3)	$ (6)

Medium- And Long-Term Debt (Nar

Medium- And Long-Term Debt (Narrative) (Details) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Unamortized debt issuance cost	$ 5	$ 5
Subsidiaries
Debt Instrument [Line Items]
Long-term Federal Home Loan Bank Advances	3,800	2,800
Blanket lien on real estate-related loans securing FHLB advances	15,800
Potential FHLB borrowing capacity	4,350
Floating-rate FHLB advances \| Subsidiaries
Debt Instrument [Line Items]
Long-term Federal Home Loan Bank Advances	$ 2,800	2,800
Weighted-average interest rate	1.8457%
Floating-rate FHLB advances \| Subsidiaries
Debt Instrument [Line Items]
Long-term Federal Home Loan Bank Advances	$ 1,000	$ 0

Medium- And Long-Term Debt (Sch

Medium- And Long-Term Debt (Schedule Of Medium- And Long-Term Debt) (Details) - USD ($) $ in Millions		3 Months Ended	12 Months Ended
		Mar. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Total medium- and long-term debt		$ 5,594	$ 4,622
Parent Company
Debt Instrument [Line Items]
Total medium- and long-term debt		594	602
Subsidiaries
Debt Instrument [Line Items]
Subordinated notes		540	555
Federal Home Loan Bank advances		3,800	2,800
Total medium- and long-term debt		5,000	4,020
3.80% subordinated notes due 2026 \| Parent Company
Debt Instrument [Line Items]
Subordinated notes	[1]	$ 248	$ 255
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-term notes	[1]	$ 346	$ 347
Stated interest rate		2.125%	2.125%
Maturity date		May 23, 2019	May 23, 2019
5.20% subordinated notes due 2017 \| Subsidiaries
Debt Instrument [Line Items]
Stated interest rate		5.20%	5.20%
Maturity date		Aug. 22, 2017	Aug. 22, 2017
4.00% subordinated notes due 2025 \| Subsidiaries
Debt Instrument [Line Items]
Subordinated notes	[1]	$ 339	$ 347
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]	$ 201	$ 208
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-term notes	[1]	$ 660	$ 665
Stated interest rate		2.50%	2.50%
Maturity date		Jun. 2, 2020	Jun. 2, 2020
Floating-rate based on FHLB auction rate due 2026 \| Subsidiaries
Debt Instrument [Line Items]
Federal Home Loan Bank advances		$ 2,800	$ 2,800
Weighted-average interest rate		1.8457%
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 2026 \| Subsidiaries \| Maximum
Debt Instrument [Line Items]
Maturity date		May 20, 2026
Floating-rate based on FHLB auction rate due 2028 \| Subsidiaries
Debt Instrument [Line Items]
Federal Home Loan Bank advances		$ 1,000	$ 0
6.0% - 6.4% fixed-rate notes due 2020 \| Subsidiaries
Debt Instrument [Line Items]
Maturity date		Jun. 30, 2020	Jun. 30, 2020
6.0% - 6.4% fixed-rate notes due 2020 \| Subsidiaries \| Minimum
Debt Instrument [Line Items]
Stated interest rate		6.00%	6.00%
6.0% - 6.4% fixed-rate notes due 2020 \| Subsidiaries \| Maximum
Debt Instrument [Line Items]
Stated interest rate		6.40%	6.40%

[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.

Accumulated Other Comprehensi67

Accumulated Other Comprehensive Loss (Schedule Of Accumulated Other Comprehensive Loss) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Investment securities, Balance at beginning of period, net of tax	$ (101)	$ (33)
Cumulative effect of change in accounting principle	1	0
Investment securities, Net unrealized holding losses arising during the period	(142)	(2)
Investment securities, Less: Benefit for income taxes	(33)	(1)
Investment securities, Net unrealized holding losses arising during the period, net of tax	(109)	(1)
Investment securities, Reclassification adjustment for net losses realized as a yield adjustment included in net income, net of tax	0	(1)
Investment securities, Change in net unrealized losses on investment securities, net of tax	(109)	0
Investment securities, Balance at end of period, net of tax	(209)	(33)
Benefit plans, Balance at beginning of period, net of tax	(350)	(350)
Benefit plans, Amortization of actuarial net loss	15	13
Benefit plans, Amortization of prior service credit	(7)	(7)
Benefit plans, Amounts recognized in other noninterest expense	8	6
Benefit plans, Less: Provision for income taxes	2	2
Benefit plans, Change in defined benefit pension and other postretirement plans adjustment, net of tax	6	4
Benefit plans, Balance at end of period, net of tax	(344)	(346)
Total accumulated other comprehensive loss at end of period, net of tax	$ (553)	$ (379)	$ (451)

Net Income Per Common Share (Na

Net Income Per Common Share (Narrative) - shares shares in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Stock Options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Average outstanding options	0	0

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
	Mar. 31, 2018	Mar. 31, 2017
Earnings Per Share [Abstract]
Net income	$ 281	$ 202
Income allocated to participating securities	2	2
Net income attributable to common shares	$ 279	$ 200
Basic average common shares	172	175
Basic net income per common share	$ 1.62	$ 1.15
Basic average common shares	172	175
Net effect of the assumed exercise of stock options	2	3
Net effect of the assumed exercise of warrants	1	2
Diluted average common shares	175	180
Diluted net income per common share	$ 1.59	$ 1.11

Employee Benefit Plans Employee

Employee Benefit Plans Employee Benefit Plans (Net Periodic Defined Benefit Cost) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Net periodic defined benefit (credit) cost	$ (5)	$ (4)
Qualified Defined Benefit Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Total other components of net benefit (credit) cost	(14)	(14)
Net periodic defined benefit (credit) cost	(7)	(7)
Qualified Defined Benefit Pension Plan \| Component recognized in salaries and benefits expense
Defined Benefit Plan Disclosure [Line Items]
Service cost	7	7
Qualified Defined Benefit Pension Plan \| Component recognized in noninterest expense
Defined Benefit Plan Disclosure [Line Items]
Interest cost	19	20
Expected return on plan assets	(41)	(40)
Amortization of prior service (credit) cost	(5)	(5)
Amortization of net loss	13	11
Non-Qualified Defined Benefit Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Total other components of net benefit (credit) cost	2	2
Net periodic defined benefit (credit) cost	2	3
Non-Qualified Defined Benefit Pension Plan \| Component recognized in salaries and benefits expense
Defined Benefit Plan Disclosure [Line Items]
Service cost	0	1
Non-Qualified Defined Benefit Pension Plan \| Component recognized in noninterest expense
Defined Benefit Plan Disclosure [Line Items]
Interest cost	2	2
Amortization of prior service (credit) cost	(2)	(2)
Amortization of net loss	2	2
Postretirement Benefit Plan
Defined Benefit Plan Disclosure [Line Items]
Net periodic defined benefit (credit) cost	0	0
Postretirement Benefit Plan \| Component recognized in noninterest expense
Defined Benefit Plan Disclosure [Line Items]
Interest cost	1	1
Expected return on plan assets	$ (1)	$ (1)

Income Taxes And Tax-Related 71

Income Taxes And Tax-Related Items Income Taxes And Tax-Related Items (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Unrecognized tax benefits	$ 10	$ 10
Reasonably possible decrease in unrecognized tax benefits in next 12 months	1
Tax-related interest and penalties payable	10	10
Net deferred tax assets	165	141
Increase in net deferred tax assets	24
State net operating loss carryforwards	4	4
Valuation allowance for deferred tax assets	$ 3	$ 3
Minimum
Years state net operating loss carryforwards expire	Dec. 31, 2018
Maximum
Years state net operating loss carryforwards expire	Dec. 31, 2027

Contingent Liabilities (Narrati

Contingent Liabilities (Narrative) (Details) - USD ($) $ in Millions	Jan. 17, 2014	Mar. 31, 2018	Mar. 31, 2017
Loss Contingencies [Line Items]
Legal fees		$ 3	$ 5
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		$ 28
Butte Local Development v. Masters Group v. Comerica Bank
Loss Contingencies [Line Items]
Amount of damages awarded by the jury	$ 52

Restructuring Charges (Narrativ

Restructuring Charges (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$ 16	$ 11
Business Bank
Restructuring Cost and Reserve [Line Items]
Restructuring charges	9	6
Retail Bank
Restructuring Cost and Reserve [Line Items]
Restructuring charges	5	4
Wealth Management
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$ 2	$ 1

Restructuring Charges (Schedule

Restructuring Charges (Schedule of Changes in Restructuring Reserves) (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2018	Mar. 31, 2017
Restructuring Cost and Reserve [Line Items]
Balance at beginning of period		$ 15	$ 18
Restructuring charges		16	11
Payments		(12)	(13)
Adjustments for non-cash charges	[1]		(3)
Balance at end of period		19	13
Total restructuring charges incurred to date		$ 154
Expected completion date of restructuring activities		Dec. 31, 2018
Employee costs
Restructuring Cost and Reserve [Line Items]
Balance at beginning of period		$ 8	10
Restructuring charges		5	1
Payments		(3)	(4)
Adjustments for non-cash charges	[1]		0
Balance at end of period		10	7
Total restructuring charges incurred to date		67
Facilities costs
Restructuring Cost and Reserve [Line Items]
Balance at beginning of period		0	4
Restructuring charges		1	1
Payments		(1)	(5)
Adjustments for non-cash charges	[1]		0
Balance at end of period		0	0
Total restructuring charges incurred to date		18
Technology costs
Restructuring Cost and Reserve [Line Items]
Balance at beginning of period		6	0
Restructuring charges		10	6
Payments		(7)	0
Adjustments for non-cash charges	[1]		(3)
Balance at end of period		9	3
Total restructuring charges incurred to date		36
Other costs
Restructuring Cost and Reserve [Line Items]
Balance at beginning of period		1	4
Restructuring charges		0	3
Payments		(1)	(4)
Adjustments for non-cash charges	[1]		0
Balance at end of period		0	$ 3
Total restructuring charges incurred to date		33
Minimum
Restructuring Cost and Reserve [Line Items]
Total expected restructuring charges	[2]	185
Minimum \| Employee costs
Restructuring Cost and Reserve [Line Items]
Total expected restructuring charges	[2]	70
Minimum \| Facilities costs
Restructuring Cost and Reserve [Line Items]
Total expected restructuring charges	[2]	20
Minimum \| Technology costs
Restructuring Cost and Reserve [Line Items]
Total expected restructuring charges	[2]	60
Minimum \| Other costs
Restructuring Cost and Reserve [Line Items]
Total expected restructuring charges	[2]	35
Maximum
Restructuring Cost and Reserve [Line Items]
Total expected restructuring charges	[2]	195
Maximum \| Employee costs
Restructuring Cost and Reserve [Line Items]
Total expected restructuring charges	[2]	70
Maximum \| Facilities costs
Restructuring Cost and Reserve [Line Items]
Total expected restructuring charges	[2]	25
Maximum \| Technology costs
Restructuring Cost and Reserve [Line Items]
Total expected restructuring charges	[2]	65
Maximum \| Other costs
Restructuring Cost and Reserve [Line Items]
Total expected restructuring charges	[2]	$ 35

[1]	Adjustments for non-cash charges primarily relate to impairments of previously capitalized software costs in Technology Costs.
[2]	Restructuring activities are expected to be substantially completed by 12/31/2018.

Business Segment Information (N

Business Segment Information (Narrative) (Details)	3 Months Ended
Business Segment Information (Narrative) (Details)	Mar. 31, 2018segmentsmarkets
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
		Mar. 31, 2018	Mar. 31, 2017
Net interest income (expense)		$ 549	$ 470
Provision for credit losses		12	16
Total noninterest income		244	271
Noninterest expenses		446	457
Provision (benefit) for income taxes		(54)	(66)
Net income (loss)		281	202
Net credit-related charge-offs (recoveries)		28	33
Assets, average		70,326	71,819
Loans, average		48,421	47,900
Deposits, average		$ 56,090	$ 57,779
Return on average assets	[1],[2]	1.62%	1.14%
Efficiency ratio	[3],[4]	56.33%	61.71%
Tax benefits from employee stock transactions		$ 19	$ 24
Business Bank
Net interest income (expense)		330	332
Provision for credit losses		10	10
Total noninterest income		121	144
Noninterest expenses		184	197
Provision (benefit) for income taxes		(59)	(92)
Net income (loss)		198	177
Net credit-related charge-offs (recoveries)		18	30
Assets, average		38,911	38,091
Loans, average		37,368	36,754
Deposits, average		$ 27,314	$ 29,648
Return on average assets	[1]	2.07%	1.89%
Efficiency ratio	[3]	40.72%	41.39%
Retail Bank
Net interest income (expense)		$ 165	$ 160
Provision for credit losses		4	12
Total noninterest income		42	48
Noninterest expenses		177	179
Provision (benefit) for income taxes		(6)	(6)
Net income (loss)		20	11
Net credit-related charge-offs (recoveries)		12	5
Assets, average		6,427	6,525
Loans, average		5,807	5,895
Deposits, average		$ 24,064	$ 23,795
Return on average assets	[1]	0.33%	0.18%
Efficiency ratio	[3]	85.03%	86.01%
Wealth Management
Net interest income (expense)		$ 41	$ 41
Provision for credit losses		(4)	(1)
Total noninterest income		68	64
Noninterest expenses		72	70
Provision (benefit) for income taxes		(10)	(13)
Net income (loss)		31	23
Net credit-related charge-offs (recoveries)		(2)	(2)
Assets, average		5,373	5,406
Loans, average		5,246	5,251
Deposits, average		$ 3,796	$ 3,978
Return on average assets	[1]	2.30%	1.71%
Efficiency ratio	[3]	67.10%	67.17%
Finance
Net interest income (expense)		$ 1	$ (71)
Provision for credit losses		0	0
Total noninterest income		11	11
Noninterest expenses		(1)	(1)
Provision (benefit) for income taxes		(1)	24
Net income (loss)		12	(35)
Net credit-related charge-offs (recoveries)		0	0
Assets, average		13,779	13,944
Loans, average		0	0
Deposits, average		823	142
Other
Net interest income (expense)		12	8
Provision for credit losses		2	(5)
Total noninterest income		2	4
Noninterest expenses		14	12
Provision (benefit) for income taxes	[5]	22	21
Net income (loss)		20	26
Net credit-related charge-offs (recoveries)		0	0
Assets, average		5,836	7,853
Loans, average		0	0
Deposits, average		$ 93	$ 216

[1]	Return on average assets is calculated based on the greater of average assets or average liabilities and attributed equity.
[2]	Return on average assets is calculated based on the greater of average assets or average liabilities and attributed equity.
[3]	Noninterest expenses as a percentage of the sum of net interest income and noninterest income excluding net securities gains (losses).
[4]	Noninterest expenses as a percentage of the sum of net interest income and noninterest income excluding net securities gains (losses).
[5]	Included tax benefits from employee stock transactions of $19 million and $24 million for the three months ended March 31, 2018 and 2017, respectively.

Business Segment Information (M

Business Segment Information (Market Segment Financial Results) (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2018	Mar. 31, 2017
Net interest income (expense)		$ 549	$ 470
Provision for credit losses		12	16
Noninterest income		244	271
Noninterest expenses		446	457
Provision (benefit) for income taxes		(54)	(66)
Net income (loss)		281	202
Net credit-related charge-offs (recoveries)		28	33
Assets, average		70,326	71,819
Loans, average		48,421	47,900
Deposits, average		$ 56,090	$ 57,779
Return on average assets	[1],[2]	1.62%	1.14%
Efficiency ratio	[3],[4]	56.33%	61.71%
Tax benefits from employee stock transactions		$ 19	$ 24
Michigan
Net interest income (expense)		169	170
Provision for credit losses		33	(2)
Noninterest income		73	83
Noninterest expenses		144	150
Provision (benefit) for income taxes		(16)	(37)
Net income (loss)		49	68
Net credit-related charge-offs (recoveries)		(1)	(3)
Assets, average		13,395	13,254
Loans, average		12,604	12,586
Deposits, average		$ 21,227	$ 22,150
Return on average assets	[2]	0.88%	1.20%
Efficiency ratio	[4]	59.61%	59.50%
California
Net interest income (expense)		$ 180	$ 171
Provision for credit losses		(2)	21
Noninterest income		39	41
Noninterest expenses		106	96
Provision (benefit) for income taxes		(30)	(36)
Net income (loss)		85	59
Net credit-related charge-offs (recoveries)		13	10
Assets, average		18,581	17,958
Loans, average		18,347	17,680
Deposits, average		$ 17,091	$ 17,243
Return on average assets	[2]	1.86%	1.32%
Efficiency ratio	[4]	48.39%	45.25%
Texas
Net interest income (expense)		$ 109	$ 113
Provision for credit losses		(13)	(9)
Noninterest income		31	32
Noninterest expenses		92	94
Provision (benefit) for income taxes		(14)	(22)
Net income (loss)		47	38
Net credit-related charge-offs (recoveries)		5	22
Assets, average		10,373	10,555
Loans, average		9,830	10,111
Deposits, average		$ 9,188	$ 10,113
Return on average assets	[2]	1.85%	1.35%
Efficiency ratio	[4]	65.63%	64.80%
Other Markets
Net interest income (expense)		$ 78	$ 79
Provision for credit losses		(8)	11
Noninterest income		88	100
Noninterest expenses		91	106
Provision (benefit) for income taxes		(15)	(16)
Net income (loss)		68	46
Net credit-related charge-offs (recoveries)		11	4
Assets, average		8,362	8,255
Loans, average		7,640	7,523
Deposits, average		$ 7,668	$ 7,915
Return on average assets	[2]	3.32%	2.13%
Efficiency ratio	[4]	54.97%	59.31%
Finance & Other
Net interest income (expense)		$ 13	$ (63)
Provision for credit losses		2	(5)
Noninterest income		13	15
Noninterest expenses		13	11
Provision (benefit) for income taxes	[5]	21	45
Net income (loss)		32	(9)
Net credit-related charge-offs (recoveries)		0	0
Assets, average		19,615	21,797
Loans, average		0	0
Deposits, average		$ 916	$ 358

[1]	Return on average assets is calculated based on the greater of average assets or average liabilities and attributed equity.
[2]	Return on average assets is calculated based on the greater of average assets or average liabilities and attributed equity.
[3]	Noninterest expenses as a percentage of the sum of net interest income and noninterest income excluding net securities gains (losses).
[4]	Noninterest expenses as a percentage of the sum of net interest income and noninterest income excluding net securities gains (losses).
[5]	Included tax benefits from employee stock transactions of $19 million and $24 million for the three months ended March 31, 2018 and 2017, respectively.

Revenue from Contracts with C78

Revenue from Contracts with Customers Revenue from Contracts with Customers (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2018		Mar. 31, 2017
Card fees		$ 59	[1]	$ 77
Service charges on deposit accounts		54	[1]	58
Fiduciary income		52		49
Commercial loan servicing fees	[2]	4		3
Brokerage fees		7		5
Other noninterest income	[3]	12		17
Total revenue from contracts with customers		188		209
Other sources of noninterest income		56		62
Total noninterest income		244		271
Business Bank
Card fees		47	[1]	64
Service charges on deposit accounts		30	[1]	32
Fiduciary income		0		0
Commercial loan servicing fees	[2]	4		3
Brokerage fees		0		0
Other noninterest income	[3]	3		4
Total revenue from contracts with customers		84		103
Other sources of noninterest income		37		41
Total noninterest income		121		144
Retail Bank
Card fees		11	[1]	12
Service charges on deposit accounts		23	[1]	25
Fiduciary income		0		0
Commercial loan servicing fees	[2]	0		0
Brokerage fees		0		0
Other noninterest income	[3]	5		8
Total revenue from contracts with customers		39		45
Other sources of noninterest income		3		3
Total noninterest income		42		48
Wealth Management
Card fees		1	[1]	1
Service charges on deposit accounts		1	[1]	1
Fiduciary income		52		49
Commercial loan servicing fees	[2]	0		0
Brokerage fees		7		5
Other noninterest income	[3]	4		5
Total revenue from contracts with customers		65		61
Other sources of noninterest income		3		3
Total noninterest income		68		64
Finance & Other
Card fees		0	[1]	0
Service charges on deposit accounts		0	[1]	0
Fiduciary income		0		0
Commercial loan servicing fees	[2]	0		0
Brokerage fees		0		0
Other noninterest income	[3]	0		0
Total revenue from contracts with customers		0		0
Other sources of noninterest income		13		15
Total noninterest income		13		15
Adoption of Topic 606 change in presentation
Card fees		34		$ 25
Decrease in card fees due to change in presentation		34
Decrease in service charges on deposit accounts due to change in presentation		$ 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 $34 million and service charges on deposit accounts by $1 million for the first quarter 2018. Refer to note 1 for further information.
[2]	Included in commercial lending fees on the Consolidated Statements of Comprehensive Income.
[3]	Excludes derivative, warrant and other miscellaneous income.