Consolidated Statement of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Operating Activities
Net income	$ 7,558	$ 5,418	$ 5,346
Adjustments to reconcile net income to net cash provided (used) by operating activities
Provision For Credit Losses	3,175	773	408
Depreciation and amortization	1,497	1,315	1,129
Deferred income taxes (benefit)	(2,239)	303	133
Net gains on sales of securities	(305)
Changes in fair value of mortgage servicing rights	799	645	172
Gain on sale of BlackRock	(5,740)
Undistributed earnings of BlackRock	(174)	(531)	(525)
Net change in
Trading securities and other short-term investments	957	560	(893)
Loans held for sale	(372)	(123)	1,635
Other assets	(927)	(788)	108
Accrued expenses and other liabilities	(254)	132	295
Other	684	(341)	32
Net cash provided (used) by operating activities	4,659	7,363	7,840
Sales
Securities available for sale	13,851	7,755	7,505
Net proceeds from sale of BlackRock	14,225
Loans	1,894	1,664	1,323
Repayments/maturities
Securities available for sale	30,901	11,974	9,388
Securities held to maturity	60	3,348	2,447
Purchases
Securities available for sale	(45,356)	(23,739)	(23,418)
Securities held to maturity	(53)	(1,751)	(3,370)
Loans	(1,982)	(1,027)	(690)
Net change in
Federal funds sold and resale agreements	1,738	4,899	(5,837)
Interest-earning deposits with banks	(61,760)	(12,520)	17,702
Loans	(3,376)	(14,963)	(7,335)
Net cash received from divestiture activity		75
Other	(1,264)	(705)	(1,684)
Net cash provided (used) by investing activities	(51,122)	(24,990)	(3,969)
Net change in
Noninterest-bearing deposits	39,851	(1,166)	(6,016)
Interest-bearing deposits	36,947	21,882	8,690
Federal funds purchased and repurchase agreements	(5,861)	4,260	392
Short-term Federal Home Loan Bank borrowings	(6,300)
Short-term Federal Home Loan Bank borrowings		4,800	1,500
Commercial paper			(100)
Other borrowed funds	123	(495)	20
Sales/issuances
Federal Home Loan Bank borrowings	9,060	12,040	9,500
Bank notes and senior debt	3,487	8,977	3,238
Subordinated debt		744	1,243
Other borrowed funds	647	1,131	500
Preferred stock
Common and treasury stock	65	90	69
Repayments/maturities
Federal Home Loan Bank borrowings	(15,601)	(22,000)	(10,536)
Bank notes and senior debt	(9,047)	(5,600)	(6,175)
Subordinated debt		(700)	(575)
Other borrowed funds	(639)	(1,174)	(548)
Preferred stock redemption	(480)
Acquisition of treasury stock	(1,624)	(3,578)	(2,877)
Preferred stock cash dividends paid	(229)	(236)	(236)
Common stock cash dividends paid	(1,980)	(1,895)	(1,601)
Net cash provided (used) by financing activities	48,419	17,080	(3,512)
Net Increase (Decrease) In Cash And Due From Banks And Restricted Cash	1,956	(547)	359
Net cash provided by discontinued operations	11,542	299	264
Net cash provided (used) by continuing operations	(9,586)	(846)	95
Cash and due from banks and restricted cash at beginning of period	5,061	5,608	5,249
Cash and due from banks and restricted cash at end of period	7,017	5,061	5,608
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents [Abstract]
Cash and due from banks at end of period (unrestricted cash)	6,636	5,061	5,608
Restricted cash	381
Supplemental Disclosures
Interest paid	1,292	3,742	2,835
Income taxes paid	3,410	430	372
Income taxes refunded	10	17	468
Leased assets obtained in exchange for new operating lease liabilities	122	317
Right-of-use assets recognized at adoption of ASU 2016-02		2,004
Non-cash Investing and Financing Items
Transfer from loans to loans held for sale, net	1,379	958	403
Transfer from loans to foreclosed assets	64	174	193
Transfer from trading securities to investment securities	$ 289	$ 328