Parent Company - Condensed Cash Flow Statements (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Condensed Financial Statement
Net cash provided by (used for) operating activities	$ 33,971	$ (25,231)	$ 40,773
Cash flows from investing activities
Payments for purchases of investment securities	(69,571)	(59,777)	(42,586)
Proceeds from sales of investment securities	20,652	13,750	17,151
Proceeds from paydowns and maturities of investment securities	40,916	24,517	12,012
Net cash provided by (used for) investing activities	(49,897)	(37,898)	(33,561)
Cash flows from financing activities
Issuance of preferred stock, net of issuance costs	1,275	0	497
Proceeds from issuance of Borrowings	90,273	60,726	30,605
Payments for borrowings	(70,124)	(50,484)	(40,548)
Payments for repurchases of common stock and employee tax withholdings	(12,075)	(1,890)	(5,954)
Payments for cash dividends	(4,171)	(2,739)	(2,627)
Other financing activities	97	(40)	(147)
Net cash provided by (used for) financing activities	41,547	83,784	(11,966)
Effect of exchange rate changes on cash and cash equivalents	(3,550)	2,828	(271)
Net increase (decrease) in cash and cash equivalents	22,071	23,483	(5,025)
Cash and cash equivalents, at beginning of period	105,654	82,171	87,196
Cash and cash equivalents, at end of period	127,725	105,654	82,171
Cash and cash equivalents:
Cash and due from banks	8,394	9,792
Supplemental Disclosure of Cash Flow Information
Cash payments for interest	1,303	4,120	12,511
Cash payments for income taxes, net of refunds	4,231	2,591	1,908
Parent Company
Condensed Financial Statement
Net cash provided by (used for) operating activities	4,257	14,202	24,175
Cash flows from investing activities
Payments for purchases of investment securities	(9,297)	(9,310)	(22,408)
Proceeds from sales of investment securities	2,611	2,013	4,671
Proceeds from paydowns and maturities of investment securities	5,636	5,651	3,157
Securities purchased under agreements to resell with affiliates	13,581	(24,584)	15,422
Securities sold under agreements to repurchase with affiliates	(7,422)	19,719	4,631
Advances to and investments in subsidiaries	(17,083)	(13,832)	(9,210)
Net cash provided by (used for) investing activities	(11,974)	(20,343)	(3,737)
Cash flows from financing activities
Issuance of preferred stock, net of issuance costs	1,275	0	497
Proceeds from issuance of Borrowings	42,098	25,587	8,337
Payments for borrowings	(28,592)	(22,105)	(24,282)
Payments for repurchases of common stock and employee tax withholdings	(12,075)	(1,890)	(5,954)
Payments for cash dividends	(4,171)	(2,739)	(2,627)
Net change in advances from subsidiaries	17,042	7,194	4,378
Other financing activities	0	(498)	12
Net cash provided by (used for) financing activities	15,577	5,549	(19,639)
Effect of exchange rate changes on cash and cash equivalents	380	(316)	(271)
Net increase (decrease) in cash and cash equivalents	8,240	(908)	528
Cash and cash equivalents, at beginning of period	7,102	8,010	7,482
Cash and cash equivalents, at end of period	15,342	7,102	8,010
Cash and cash equivalents:
Cash and due from banks	100	20	9
Deposits with bank subsidiaries	15,242	7,082	8,001
Restricted cash	441	381	0
Supplemental Disclosure of Cash Flow Information
Cash payments for interest	2,970	3,472	4,677
Cash payments for income taxes, net of refunds	2,775	1,364	1,186
Settlements received from subsidiaries	$ 3,000	$ 1,600	$ 1,600