Investments in Securities Available-for-sale Securities 1 (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Investments, Debt and Equity Securities [Abstract]
Gross realized gains	$ 40		$ 182		$ 566
Gross realized losses	16		90		293
Total proceeds	$ 634	[1]	$ 2,152	[1]	$ 7,207	[1]

[1] Excludes proceeds from the initial sale of securities from new portfolio securitizations included in “Note 2, Consolidations and Transfers of Financial Assets.”