Capital (By Redemption Period) (Details) - USD ($) $ in Millions		Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019	Dec. 31, 2018
Financial Instruments Subject to Mandatory Redemption, Settlement Terms, Share Value, Amount [Abstract]
Within 1 year		$ 81	$ 135
Past contractual redemption date because of remaining activity	[1]	2	3
Total		$ 83	$ 138	$ 227	$ 227

[1] Represents mandatorily redeemable capital stock that is past the end of the contractual redemption period because of outstanding activity.