Investments in Securities Available-for-sale Securities 1 (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2012		Jun. 30, 2011		Jun. 30, 2012		Jun. 30, 2011
Schedule of Available-for-sale Securities [Line Items]
Gross realized gains	$ 9		$ 73		$ 27		$ 133
Gross realized losses	1		47		10		53
Total proceeds	$ 132	[1]	$ 839	[1]	$ 400	[1]	$ 1,229	[1]

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