Parent Company Financial Statements - Statement of Income (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Condensed Financial Statements, Captions [Line Items]
Total revenue	$ 11,703	$ 11,756	$ 12,131
Other	965	1,262	1,176
Total expenses	8,716	9,034	9,015
Income tax expense	479	470	508
Equity in undistributed income of consolidated subsidiaries and unconsolidated entities:
Net income	2,420	2,242	2,593
Parent Company
Condensed Financial Statements, Captions [Line Items]
Cash dividends from consolidated banking subsidiary	2,721	3,300	785
Cash dividends from consolidated non-banking subsidiaries and unconsolidated entities	118	285	41
Other, net	92	149	58
Total revenue	2,931	3,734	884
Interest expense	324	415	381
Other	172	108	162
Total expenses	496	523	543
Income tax expense	(109)	(91)	(127)
Income before equity in undistributed income of consolidated subsidiaries and unconsolidated entities	2,544	3,302	468
Equity in undistributed income of consolidated subsidiaries and unconsolidated entities:
Consolidated banking subsidiary	(277)	(1,070)	1,944
Consolidated non-banking subsidiaries and unconsolidated entities	153	10	181
Net income	$ 2,420	$ 2,242	$ 2,593