Investments in Securities - Investments In Trading Securities (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Schedule of Investments in Trading Securities [Line Items]
Trading, at fair value	$ 88,206	$ 136,542
Consolidated Trusts
Schedule of Investments in Trading Securities [Line Items]
Trading, at fair value	593	793
Mortgage-related securities
Schedule of Investments in Trading Securities [Line Items]
Trading, at fair value	4,606	6,013
Fannie Mae
Schedule of Investments in Trading Securities [Line Items]
Trading, at fair value	1,576	2,404
Other agency
Schedule of Investments in Trading Securities [Line Items]
Trading, at fair value	2,893	3,451
Private-label and other mortgage securities
Schedule of Investments in Trading Securities [Line Items]
Trading, at fair value	137	158
Non-mortgage-related securities
Schedule of Investments in Trading Securities [Line Items]
Trading, at fair value	83,600	130,529
U.S. Treasury securities
Schedule of Investments in Trading Securities [Line Items]
Trading, at fair value	83,581	130,456
Other securities
Schedule of Investments in Trading Securities [Line Items]
Trading, at fair value	$ 19	$ 73