Investments in Securities Trading 1 (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Schedule of Investments in Trading Securities [Line Items]
Trading, at fair value	$ 136,542	$ 48,123
Consolidated Trusts [Member]
Schedule of Investments in Trading Securities [Line Items]
Trading, at fair value	793	896
Mortgage-related securities [Member]
Schedule of Investments in Trading Securities [Line Items]
Trading, at fair value	6,013	8,543
Fannie Mae [Member]
Schedule of Investments in Trading Securities [Line Items]
Trading, at fair value	2,404	3,424
Other agency [Member]
Schedule of Investments in Trading Securities [Line Items]
Trading, at fair value	3,451	4,490
Alt-A and subprime private-label securities [Member]
Schedule of Investments in Trading Securities [Line Items]
Trading, at fair value	158	629
U.S. Treasury Securities [Member]
Schedule of Investments in Trading Securities [Line Items]
Trading, at fair value	130,456	39,501
Debt Security, Corporate, US [Member]
Schedule of Investments in Trading Securities [Line Items]
Trading, at fair value	73	79
Non-mortgage-related securities [Member]
Schedule of Investments in Trading Securities [Line Items]
Trading, at fair value	$ 130,529	$ 39,580