Earnings Per Common Share (Details) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended																9 Months Ended
	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010	Dec. 31, 2012 Stock Options [Member]	Dec. 31, 2011 Stock Options [Member]	Dec. 31, 2010 Stock Options [Member]	Dec. 31, 2012 Warrant [Member]	Dec. 31, 2011 Warrant [Member]	Dec. 31, 2010 Warrant [Member]	Dec. 31, 2012 Series L Preferred Stock [Member] Convertible Preferred Stock Subject to Mandatory Redemption [Member]	Dec. 31, 2011 Series L Preferred Stock [Member] Convertible Preferred Stock Subject to Mandatory Redemption [Member]	Dec. 31, 2010 Series L Preferred Stock [Member] Convertible Preferred Stock Subject to Mandatory Redemption [Member]	Dec. 31, 2012 Series T Preferred Stock [Member]	Dec. 31, 2011 Series T Preferred Stock [Member]	Sep. 30, 2012 Exchange Agreements [Member] Non-Convertible Preferred Stock and Trust Preferred Securities [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount						163,000,000	217,000,000	271,000,000	272,000,000	272,000,000	272,000,000	62,000,000	66,000,000	107,000,000
Incremental Common Shares Attributable to Conversion of Preferred Stock															700,000,000	234,000,000
Dividends, Preferred Stock, Stock			$ 36														$ (44)
Earnings (loss) per common share
Net income (loss)	4,188		1,446		(2,238)
Preferred Stock Dividends	(1,428)		(1,361)		(1,357)
Net income (loss) applicable to common shareholders	2,760		85		(3,595)
Dividends and undistributed earnings allocated to participating securities	(2)		(1)		(4)
Net income (loss) allocated to common shareholders	2,758		84		(3,599)
Average common shares issued and outstanding (in thousands)	10,746,028,000		10,142,625,000		9,790,472,000
Earnings (loss) per common share	$ 0.26		$ 0.01		$ (0.37)
Diluted earnings (loss) per common share
Net Income (Loss) Applicable to Common Shareholders, Diluted	2,760		85		(3,595)
Undistributed Earnings, Diluted	(2)		(1)		(4)
Net Income (Loss) allocated to Common Shareholders	$ 2,758		$ 84		$ (3,599)
Dilutive potential common shares	94,826,000	[1]	112,199,000	[1]	0
Total diluted average common shares issued and outstanding (in thousands)	10,840,854,000		10,254,824,000		9,790,472,000
Diluted earnings (loss) per common share	$ 0.25		$ 0.01		$ (0.37)

[1] Includes incremental shares from RSUs, restricted stock, stock options and warrants.