Consolidated Statements of Changes in Stockholders' Equity (Unaudited) (USD $) In Millions, unless otherwise specified	Total	Preferred stock	Common stock	Additional paid-in capital	Retained earnings	Accumulated other comprehensive income/(loss)	Shares held in RSU Trust, at cost	Treasury stock, at cost
Cumulative effect of change in accounting principle at Dec. 31, 2013					$ (321)
Beginning balance at Dec. 31, 2013		11,158	4,105	93,828	115,756	1,199	(21)	(14,847)
Balance at beginning of year, adjusted at Dec. 31, 2013					115,435
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of preferred stock		3,925
Shares issued and commitments to issue common stock for employee stock-based compensation awards, and related tax effects				(1,179)
Other				(26)
Net income	5,269				5,269
Dividends declared:
Preferred stock					(227)
Common stock ($0.40 and $0.38 per share)					(1,485)
Other comprehensive income	1,077					1,077
Purchase of treasury stock								(386)
Reissuance from treasury stock								1,504
Ending balance at Mar. 31, 2014	219,329	15,083	4,105	92,623	118,992	2,276	(21)	(13,729)
Cumulative effect of change in accounting principle at Dec. 31, 2014					0
Beginning balance at Dec. 31, 2014		20,063	4,105	93,270	129,977	2,189	(21)	(17,856)
Balance at beginning of year, adjusted at Dec. 31, 2014					129,977
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of preferred stock		1,430
Shares issued and commitments to issue common stock for employee stock-based compensation awards, and related tax effects				(987)
Other				(38)
Net income	5,914				5,914
Dividends declared:
Preferred stock					(324)
Common stock ($0.40 and $0.38 per share)					(1,519)
Other comprehensive income	241					241
Purchase of treasury stock								(1,900)
Reissuance from treasury stock								1,320
Ending balance at Mar. 31, 2015	$ 235,864	$ 21,493	$ 4,015	$ 92,245	$ 134,048	$ 2,430	$ (21)	$ (18,436)