Parent Company (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Non-interest revenues
Gain on sale of securities									$ 1	$ 100	$ 136
Other									2,033	2,989	2,274
Total non-interest revenues									26,896	28,716	27,823
Interest income									7,545	7,179	7,005
Interest expense									(1,623)	(1,707)	(1,958)
Total revenues net of interest expense	$ 8,391	$ 8,193	$ 8,284	$ 7,950	$ 9,081	$ 8,303	$ 8,631	$ 8,173	32,818	34,188	32,870
Expenses
Salaries and employee benefits									4,976	6,095	6,191
Other									6,793	6,089	6,796
Total									22,892	23,153	23,150
Pretax loss	1,454	1,938	2,230	2,316	2,225	2,246	2,312	2,208	7,938	8,991	7,888
Income tax provision (benefit)									2,775	3,106	2,529
Net income	$ 899	$ 1,266	$ 1,473	$ 1,525	$ 1,447	$ 1,477	$ 1,529	$ 1,432	5,163	5,885	5,359
Parent Company [Member]
Non-interest revenues
Gain on sale of securities									0	99	135
Other									400	270	5
Total non-interest revenues									400	369	140
Interest income									172	141	134
Interest expense									(526)	(543)	(583)
Total revenues net of interest expense									46	(33)	(309)
Expenses
Salaries and employee benefits									341	275	206
Other									443	357	261
Total									784	632	467
Pretax loss									(738)	(665)	(776)
Income tax provision (benefit)									(268)	(249)	(297)
Net loss before equity in net income of subsidiaries and affiliates									(470)	(416)	(479)
Equity in net income of subsidiaries and affiliates									5,633	6,301	5,838
Net income									$ 5,163	$ 5,885	$ 5,359