Parent Company (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Non-interest revenues
Other									$ 874	$ 1,430	$ 1,360
Total non-interest revenues									28,102	34,936	32,675
Interest income									10,083	12,084	10,606
Interest expense									2,098	3,464	2,943
Total revenues net of interest expense	$ 9,351	$ 8,751	$ 7,675	$ 10,310	$ 11,365	$ 10,989	$ 10,838	$ 10,364	36,087	43,556	40,338
Expenses
Salaries and employee benefits									5,718	5,911	5,250
Other									5,325	5,856	5,664
Total expenses									27,061	31,554	28,864
Pretax income	1,858	1,364	622	452	1,986	2,266	2,219	1,958	4,296	8,429	8,122
Income tax provision (benefit)									1,161	1,670	1,201
Net income	$ 1,438	$ 1,073	$ 257	$ 367	$ 1,693	$ 1,755	$ 1,761	$ 1,550	3,135	6,759	6,921
Parent Company [Member]
Non-interest revenues
Other									480	598	426
Total non-interest revenues									480	598	426
Interest income									228	692	422
Interest expense									630	902	615
Total revenues net of interest expense									78	388	233
Expenses
Salaries and employee benefits									333	366	336
Other									562	816	607
Total expenses									895	1,182	943
Pretax income									(817)	(794)	(710)
Income tax provision (benefit)									(236)	(282)	(179)
Net loss before equity in net income of subsidiaries and affiliates									(581)	(512)	(531)
Equity in net income of subsidiaries and affiliates									3,716	7,271	7,452
Net income									$ 3,135	$ 6,759	$ 6,921