Investments in Securities Trading 1 (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Schedule of Investments in Trading Securities [Line Items]
Trading, at fair value	$ 31,504	$ 30,768
Mortgage-related securities [Member]
Schedule of Investments in Trading Securities [Line Items]
Trading, at fair value	12,038	14,462
Fannie Mae [Member]
Schedule of Investments in Trading Securities [Line Items]
Trading, at fair value	4,940	5,870
Freddie Mac [Member]
Schedule of Investments in Trading Securities [Line Items]
Trading, at fair value	1,369	1,839
Ginnie Mae [Member]
Schedule of Investments in Trading Securities [Line Items]
Trading, at fair value	166	407
Alt-A private-label securities [Member]
Schedule of Investments in Trading Securities [Line Items]
Trading, at fair value	920	1,516
Subprime private-label securities [Member]
Schedule of Investments in Trading Securities [Line Items]
Trading, at fair value	1,307	1,448
CMBS [Member]
Schedule of Investments in Trading Securities [Line Items]
Trading, at fair value	2,515	2,718
Mortgage revenue bonds [Member]
Schedule of Investments in Trading Securities [Line Items]
Trading, at fair value	722	565
Other mortgage-related securities [Member]
Schedule of Investments in Trading Securities [Line Items]
Trading, at fair value	99	99
U.S. Treasury Securities [Member]
Schedule of Investments in Trading Securities [Line Items]
Trading, at fair value	$ 19,466	$ 16,306