Investments in Securities Trading 1 (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Schedule of Investments in Trading Securities [Line Items]
Trading, at fair value	$ 111,256	$ 136,542
Mortgage-related securities [Member]
Schedule of Investments in Trading Securities [Line Items]
Trading, at fair value	5,582	6,013
Fannie Mae [Member]
Schedule of Investments in Trading Securities [Line Items]
Trading, at fair value	1,985	2,404
Other agency [Member]
Schedule of Investments in Trading Securities [Line Items]
Trading, at fair value	3,440	3,451
Private-label and other mortgage securities [Member]
Schedule of Investments in Trading Securities [Line Items]
Trading, at fair value	157	158
Non-mortgage-related securities [Member]
Schedule of Investments in Trading Securities [Line Items]
Trading, at fair value	105,674	130,529
U.S. Treasury securities [Member]
Schedule of Investments in Trading Securities [Line Items]
Trading, at fair value	105,601	130,456
Other securities [Member]
Schedule of Investments in Trading Securities [Line Items]
Trading, at fair value	73	73
Variable Interest Entity, Primary Beneficiary [Member]
Schedule of Investments in Trading Securities [Line Items]
Trading, at fair value	$ 741	$ 793