CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED) - USD ($) $ in Millions		3 Months Ended		9 Months Ended		12 Months Ended
		Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
OPERATING ACTIVITIES
Net income				$ 1,256	$ 986
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for credit losses				241	238
Originations of mortgage loans held for sale				(4,384)	(2,159)
Proceeds from sales of mortgage loans held for sale				4,259	2,372
Purchases of commercial loans held for sale				(1,450)	(1,513)
Proceeds from sales of commercial loans held for sale				1,457	1,441
Depreciation, amortization and accretion				357	371
Mortgage servicing rights valuation recovery				(3)	(1)
Debt securities impairment		$ 1	$ 1	3	6
Deferred income taxes				23	(23)
Share-based compensation				40	35
Net gain on sales of:
Debt securities		(3)	(2)	(13)	(9)
Equity securities				0	(1)
Increase in other assets				(918)	(155)
Increase (decrease) in other liabilities				339	(138)
Net cash provided by operating activities				1,207	1,450
Investment securities:
Purchases of debt securities available for sale				(3,084)	(4,088)
Proceeds from maturities and paydowns of debt securities available for sale				2,512	2,564
Proceeds from sales of debt securities available for sale				405	914
Purchases of debt securities held to maturity				0	(171)
Proceeds from maturities and paydowns of debt securities held to maturity				402	422
Purchases of equity securities, at fair value				(122)	(286)
Proceeds from sales of equity securities, at fair value				116	217
Purchases of equity securities, at cost				(568)	(307)
Proceeds from sales of equity securities, at cost				416	495
Net decrease in interest-bearing deposits in banks				50	152
Purchases of mortgage servicing rights				(16)	0
Acquisition, net of cash acquired				(533)	0
Net increase in loans and leases				(4,278)	(3,549)
Net increase in bank-owned life insurance				(31)	(34)
Premises and equipment:
Purchases				(157)	(115)
Capitalization of software				(175)	(138)
Net cash used in investing activities				(5,063)	(3,924)
FINANCING ACTIVITIES
Net increase in deposits				1,986	3,431
Net decrease in federal funds purchased and securities sold under agreements to repurchase				(441)	(695)
Net decrease in other short-term borrowed funds				(3,107)	(1,708)
Proceeds from issuance of long-term borrowed funds				17,503	12,108
Repayments of long-term borrowed funds				(10,333)	(11,501)
Treasury stock purchased				(725)	(485)
Net proceeds from issuance of preferred stock				296	0
Dividends declared and paid to common stockholders				(344)	(233)
Dividends declared and paid to preferred stockholders				(7)	(7)
Payments of employee tax withholding for share-based compensation				(13)	(20)
Net cash provided by financing activities				4,815	890
Increase in cash and cash equivalents	[1]			959	(1,584)
Cash and cash equivalents at beginning of period	[1]			3,032	3,704	$ 3,704
Cash and cash equivalents at end of period	[1]	$ 3,991	$ 2,120	$ 3,991	$ 2,120	$ 3,032

[1] Cash and cash equivalents includes cash and due from banks and interest-bearing cash and due from banks as reflected on the Consolidated Balance Sheets.