Investments in Securities Trading 1 (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2013		Dec. 31, 2012
Schedule of Investments in Trading Securities [Line Items]
Trading, at fair value	$ 32,860		$ 40,695
Mortgage-related securities [Member]
Schedule of Investments in Trading Securities [Line Items]
Trading, at fair value	16,464		22,745
Freddie Mac [Member]
Schedule of Investments in Trading Securities [Line Items]
Trading, at fair value	2,163		2,793
Ginnie Mae [Member]
Schedule of Investments in Trading Securities [Line Items]
Trading, at fair value	432		437
Alt-A private-label securities [Member]
Schedule of Investments in Trading Securities [Line Items]
Trading, at fair value	1,495		1,330
Subprime private-label securities [Member]
Schedule of Investments in Trading Securities [Line Items]
Trading, at fair value	1,411		1,319
CMBS [Member]
Schedule of Investments in Trading Securities [Line Items]
Trading, at fair value	4,177		9,826
Mortgage revenue bonds [Member]
Schedule of Investments in Trading Securities [Line Items]
Trading, at fair value	595		675
Other mortgage-related securities [Member]
Schedule of Investments in Trading Securities [Line Items]
Trading, at fair value	110		117
U.S. Treasury Securities [Member]
Schedule of Investments in Trading Securities [Line Items]
Trading, at fair value	16,396		17,950
Fannie Mae [Member]
Schedule of Investments in Trading Securities [Line Items]
Trading, at fair value	$ 6,081	[1]	$ 6,248	[1]

[1] Contains securities recognized in our condensed consolidated balance sheets due to consolidation of certain multi-class resecuritization trusts.