Reconciliation of Net Income/(Loss) to Net Income/(Loss) Available to Common Shareholders (Detail) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Net income/(loss)	$ 1,077	$ 215	$ 1,602	$ 573
Preferred dividends	(2)	(2)	(8)	(5)
Dividends and accretion of discount on preferred stock issued to the U.S. Treasury	0	0	0	(66)
Preferred Stock, Accretion of Redemption Discount	0	0	0	(74)
Dividends and undistributed earnings allocated to unvested shares	(9)	(2)	(13)	(4)
Net income/(loss) available to common shareholders	1,066	211	1,581	424
Average basic common shares	534,506,000	531,928,000	533,859,000	521,248,000
Weighted Average Number Diluted Shares Outstanding Adjustment [Abstract]
Stock options	1,000,000	1,000,000	1,000,000	2,000,000
Restricted stock	3,000,000	2,000,000	3,000,000	2,000,000
Average diluted common shares	538,699,000	535,395,000	537,538,000	524,888,000
Net income/(loss) per average common share - diluted	$ 1.98	$ 0.39	$ 2.94	$ 0.81
Net income/(loss) per average common share - basic	$ 1.99	$ 0.40	$ 2.96	$ 0.81
Retained Earnings [Member]
Net income/(loss)			1,602	573
Preferred dividends			$ (8)	$ (5)