Shareholders' Equity (Narrative) (Details) (USD $)	1 Months Ended	9 Months Ended	12 Months Ended								1 Months Ended	12 Months Ended			0 Months Ended	12 Months Ended			12 Months Ended
	Mar. 30, 2012	Dec. 31, 2012	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010		Dec. 31, 2009	Aug. 21, 2012	Aug. 31, 2012 Series C Preferred Stock	Dec. 31, 2012 Series C Preferred Stock	Aug. 21, 2012 Series C Preferred Stock	Dec. 31, 2011 Series C Preferred Stock	Oct. 04, 2012 Series A Preferred Stock	Dec. 31, 2012 Series A Preferred Stock	Sep. 04, 2012 Series A Preferred Stock	Dec. 31, 2011 Series A Preferred Stock	Dec. 31, 2011 Preferred Stock [Member]	Dec. 31, 2012 Preferred Stock [Member] Series C Preferred Stock	Dec. 31, 2012 Preferred Stock [Member] Series A Preferred Stock
Shareholders' Equity [Line Items]
Depositary shares issued and sold										20,000,000
Ownership interest in non-cumulative perpetual preferred stock per depositary share													$ 0.00025
Ownership of one depositary share ownership interest in one share of non cumulative perpetual preferred series C stock		0.025%	0.025%
Preferred stock liquidation preference per share												$ 100,000			$ 100,000		$ 100,000
Value of preferred stock series A redeemed															$ 500,000,000	$ 500,000,000					$ 500,000,000
Depositary shares liquidation preference per share		$ 25	$ 25
Preferred stock annual dividend rate												5.25%
Preferred stock dividend declared			29,000,000	[1]	20,000,000	[1]	0	[1]			8,000,000	8,000,000
Preferred stock shares issued												5,000		5,000		5,001	5,001	5,001
Value of preferred stock issued					500,000,000							488,000,000							500,000,000	488,000,000
Preferred stock dividend unpaid amount															21,000,000
Authorized repurchase amount under stock repurchase program	1,800,000,000
Average cost per share of treasury stock acquired		$ 43.11			$ 41.38
Approximate aggregate cost of common stock acquired		1,440,000,000			675,000,000
Remaining amount available for repurchase under program			360,000,000
Common stock acquired (shares)		33,400,000			16,300,000
Shares purchased and held in trust		387,000	387,000		406,000
Unrealized pre-tax gains (losses) included in other comprehensive income					67,000,000		76,000,000		(728,000,000)
Realized (losses) gains from sales of investment securities			55,000,000		140,000,000		(55,000,000)
Deferred taxes related to unrealized pre-tax gains					$ 27,000,000		$ 30,000,000		$ 291,000,000

[1] Amount for 2012 included $8 million related to Series C preferred stock issued in August 2012. Remaining amount for 2012 and amount for 2011 were related to Series A preferred stock, which was redeemed in October 2012.