Investment Securities (Narrative) (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2012 securities countries	Sep. 30, 2011	Sep. 30, 2012 countries	Sep. 30, 2011	Dec. 31, 2011
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Aggregate investment securities carried	$ 43,070,000,000		$ 43,070,000,000		$ 44,660,000,000
Impairment associated with expected credit losses	(1,000,000)	(7,000,000)	(14,000,000)	(36,000,000)
Impairment associated with adverse changes in timing of expected future cash flows	(5,000,000)	(3,000,000)	(13,000,000)	(12,000,000)
Available-for-sale Securities, Gross Unrealized Losses	1,090,000,000		1,090,000,000		1,652,000,000
OTTI on Spanish Italian Irish Portugese Mortgage and Asset Backed Securities	0		0
Number Of Peripheral European Countries	4		4
Recovery of claimed amounts	20.00%
Net impairment losses	6,000,000	10,000,000	27,000,000	56,000,000
Gross pre-tax unrealized losses on securities			1,200,000,000
Available-for-sale and Held-to-Maturity, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions	1,164
Non-Agency Prime [Member]
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Other than Temporary Impairment, Credit Losses Recognized in Earnings, Period Increase (Decrease)	1,000,000		8,000,000
Impairment associated with expected credit losses	(1,000,000)	(7,000,000)	(14,000,000)	(36,000,000)
Other than Temporary Impairment Losses, Investments, Portion Recognized in Earnings, Net		8,000,000		8,000,000
Impairment associated with adverse changes in timing of expected future cash flows	5,000,000	3,000,000	13,000,000	12,000,000
Net impairment losses	(6,000,000)	(10,000,000)	(27,000,000)	(56,000,000)
Federal Family Education Loan Program [Member]
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
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
European Periphery [Member]
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Total exposure to asset backed Securities	693,000,000		693,000,000
Available-for-sale Securities, Gross Unrealized Losses	43,000,000		43,000,000
European Periphery [Member] | Non-Agency Prime [Member]
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Other than Temporary Impairment, Credit Losses Recognized in Earnings, Period Increase (Decrease)			6,000,000
Spain
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Total exposure to asset backed Securities	267,000,000		267,000,000
Italy
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Total exposure to asset backed Securities	238,000,000		238,000,000
Ireland
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Total exposure to asset backed Securities	110,000,000		110,000,000
Portugal
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Total exposure to asset backed Securities	78,000,000		78,000,000
Minimum [Member]
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Percentage change in additional house price declines			9.00%
Maximum [Member]
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Percentage change in additional house price declines			20.00%
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)	6,000,000
Available-for-sale Securities, Gross Unrealized Losses	30,000,000		30,000,000		107,000,000
Net impairment losses	$ 5,000,000		$ 19,000,000