Investment Securities (Narrative) (Details) (USD $)	12 Months Ended
	Dec. 31, 2011 securities		Dec. 31, 2010
Aggregate investment securities carried	$ 44,660,000,000		$ 44,810,000,000
Recovery of claimed amounts	20.00%
Gross pre-tax unrealized losses on securities	1,960,000,000
Number of investment securities	1,703
Credit-related other-than-temporary impairment	73,000,000
Available for sale, Amortized Cost	100,013,000,000		82,329,000,000
Proceeds from sale of securities			11,000,000,000
Pre-tax net loss on sale of securities			344,000,000
Securities sold included as held to maturity	4,800,000,000
Net pre-tax loss on sale of held-to-maturity securities	119,000,000
Unrealized loss on available-for-sale securities	1,652,000,000		1,574,000,000
Number of peripheral European countries	5
Asset-Backed Securities [Member]
Available for sale, Amortized Cost	32,905,000,000		27,264,000,000
Proceeds from sale of securities			4,300,000,000
Unrealized loss on available-for-sale securities	1,297,000,000		1,185,000,000
Non-Agency Mortgage Backed Securities [Member]
Proceeds from sale of securities			4,100,000,000
Mortgage-Backed Securities [Member]
Proceeds from sale of securities			2,500,000,000
Federal Family Education Loan Program [Member]
Federal government credit support guarantee, percentage minimum	97.00%
Collective credit support, percentage minimum	100.00%
Student Loans [Member]
Available for sale, Amortized Cost	17,187,000,000	[1]	14,975,000,000	[1]
Total exposure to asset backed Securities	1,000,000,000
Unrealized loss on available-for-sale securities	711,000,000	[1]	652,000,000	[1]
European Periphery [Member]
Total exposure to asset backed Securities	1,080,000,000
Unrealized loss on available-for-sale securities	122,000,000
Spain [Member]
Total exposure to asset backed Securities	424,000,000
Italy [Member]
Total exposure to asset backed Securities	373,000,000
Greece [Member]
Total exposure to asset backed Securities	99,000,000
Ireland [Member]
Total exposure to asset backed Securities	114,000,000
Portugal [Member]
Total exposure to asset backed Securities	$ 69,000,000
Maximum [Member]
Percentage change in additional house price declines	15.00%
Minimum [Member]
Percentage change in additional house price declines	5.00%

[1] Substantially composed of securities guaranteed by the federal government with respect to the payment of principal and interest.