Investments in Securities Trading 1 (Details) - USD ($) $ in Millions	Jun. 30, 2019	Dec. 31, 2018
Schedule of Investments in Trading Securities [Line Items]
Trading, at fair value	$ 42,866	$ 41,867
Mortgage-related securities [Member]
Schedule of Investments in Trading Securities [Line Items]
Trading, at fair value	7,516	6,276
Fannie Mae [Member]
Schedule of Investments in Trading Securities [Line Items]
Single Security recognized mortgage related securities	1,400
Trading, at fair value	3,151	1,467
Other agency [Member]
Schedule of Investments in Trading Securities [Line Items]
Trading, at fair value	3,629	3,503
Private-label and other mortgage securities [Member]
Schedule of Investments in Trading Securities [Line Items]
Trading, at fair value	736	1,306
Non-mortgage-related securities [Member]
Schedule of Investments in Trading Securities [Line Items]
Trading, at fair value	35,350	35,591
U.S. Treasury securities [Member]
Schedule of Investments in Trading Securities [Line Items]
Trading, at fair value	35,266	35,502
Other securities [Member]
Schedule of Investments in Trading Securities [Line Items]
Trading, at fair value	84	89
Variable Interest Entity, Primary Beneficiary [Member]
Schedule of Investments in Trading Securities [Line Items]
Trading, at fair value	$ 983	$ 32