Trading Securities (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Trading Securities
Trading securities	$ 1,766	$ 661
Net unrealized gain/(loss) on trading securities	(2)	(2)	$ 0
US Treasury Securities [Member]
Trading Securities
Trading securities	1,762	0
GSEs – Federal Farm Credit Bank (FFCB) bonds
Trading Securities
Trading securities	0	656
MBS – Other U.S. obligations – Ginnie Mae
Trading Securities
Trading securities	$ 4	$ 5