Parent Company (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Non-interest revenues
Other									$ 1,360	$ 1,457	$ 1,678
Total non-interest revenues									32,675	30,427	29,659
Interest income									10,606	8,563	7,484
Interest expense									2,943	2,112	1,705
Total revenues net of interest expense	$ 10,474	$ 10,144	$ 10,002	$ 9,718	$ 9,707	$ 9,290	$ 9,172	$ 8,709	40,338	36,878	35,438
Expenses
Salaries and employee benefits									5,250	5,258	5,259
Other									5,671	5,634	4,942
Total Expenses									28,864	26,693	25,369
Pretax loss	1,831	2,118	2,091	2,082	1,798	1,831	1,957	1,839	8,122	7,425	8,042
Income tax provision (benefit)									1,201	4,677	2,667
Net income	$ 2,010	$ 1,654	$ 1,623	$ 1,634	$ (1,206)	$ 1,359	$ 1,344	$ 1,251	6,921	2,748	5,375
Parent Company [Member]
Non-interest revenues
Other									426	358	391
Total non-interest revenues									426	358	391
Interest income									422	258	196
Interest expense									615	493	515
Total revenues net of interest expense									233	123	72
Expenses
Salaries and employee benefits									336	362	388
Other									607	553	510
Total Expenses									943	915	898
Pretax loss									(710)	(792)	(826)
Income tax provision (benefit)									(179)	(354)	(327)
Net loss before equity in net income of subsidiaries and affiliates									(531)	(438)	(499)
Equity in net income of subsidiaries and affiliates									7,452	3,186	5,874
Net income									$ 6,921	$ 2,748	$ 5,375