Investment Securities (Narrative) (Details) (USD $)	3 Months Ended		6 Months Ended			3 Months Ended			6 Months Ended		3 Months Ended						6 Months Ended		3 Months Ended	6 Months Ended
	Jun. 30, 2012 securities countries	Jun. 30, 2011	Jun. 30, 2012 countries	Jun. 30, 2011	Dec. 31, 2011	Jun. 30, 2012 Non-Agency Prime [Member]	Jun. 30, 2011 Non-Agency Prime [Member]	Mar. 31, 2011 Non-Agency Prime [Member]	Jun. 30, 2012 Non-Agency Prime [Member]	Jun. 30, 2011 Non-Agency Prime [Member]	Jun. 30, 2012 Federal Family Education Loan Program [Member]	Jun. 30, 2012 European Periphery [Member]	Jun. 30, 2012 Spain	Jun. 30, 2012 Italy	Jun. 30, 2012 Ireland	Jun. 30, 2012 Portugal	Jun. 30, 2012 Minimum [Member]	Jun. 30, 2012 Maximum [Member]	Jun. 30, 2012 Non-US Debt Securities, Mortgage-Backed Securities [Member]	Jun. 30, 2012 Non-US Debt Securities, Mortgage-Backed Securities [Member]	Dec. 31, 2011 Non-US Debt Securities, Mortgage-Backed Securities [Member]
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Other than Temporary Impairment, Credit Losses Recognized in Earnings, Period Increase (Decrease)						$ 3,000,000			$ 7,000,000			$ 6,000,000							$ 6,000,000	$ 6,000,000
Aggregate investment securities carried	38,310,000,000		38,310,000,000		44,660,000,000
Impairment associated with expected credit losses	(9,000,000)	(24,000,000)	(13,000,000)	(29,000,000)		(9,000,000)	(24,000,000)		(13,000,000)	(29,000,000)
Other than Temporary Impairment Losses, Investments, Portion Recognized in Earnings, Net							8,000,000			8,000,000
Federal government credit support guarantee, percentage minimum											97.00%
Collective credit support, percentage minimum											100.00%
Concentration Risk, Credit Risk, Financial Instrument, Maximum Exposure											1,000,000,000
Impairment associated with adverse changes in timing of expected future cash flows	(4,000,000)	(3,000,000)	(8,000,000)	(9,000,000)		4,000,000	3,000,000		8,000,000	9,000,000
Total exposure to asset backed Securities												697,000,000	266,000,000	252,000,000	107,000,000	72,000,000
Available-for-sale Securities, Gross Unrealized Losses	1,429,000,000		1,429,000,000		1,652,000,000							71,000,000							51,000,000	51,000,000	107,000,000
OTTI on Spanish Italian Irish Portugese Mortgage and Asset Backed Securities	0		0
Percentage change in additional house price declines																	9.00%	22.00%
Number Of Peripheral European Countries	4		4
Recovery of claimed amounts	20.00%
Net impairment losses	13,000,000	35,000,000	21,000,000	46,000,000		(13,000,000)		(35,000,000)	(21,000,000)	(46,000,000)									10,000,000	14,000,000
Gross pre-tax unrealized losses on securities	$ 1,630,000,000
Available-for-sale and Held-to-Maturity, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions	1,899