Capital (Mandatorily Redeemable Capital Stock) (Details) $ in Millions		3 Months Ended
		Mar. 31, 2020 USD ($) Institutions	Mar. 31, 2019 USD ($)	Dec. 31, 2019 Institutions
Capital [Line Items]
Financial Instruments Subject to Mandatory Redemption, Number of Stockholders | Institutions		3		3
Interest Expense on Mandatorily Redeemable Capital Stock	[1]	$ 2	$ 4
Mandatorily Redeemable Capital Stock [Roll Forward]
Balance at the beginning of the period		138	227
Reclassified from/(to) capital during the period		3	0
Repurchase of excess mandatorily redeemable capital stock		(58)	0
Balance at the end of the period		$ 83	$ 227

[1] The Bank excludes interest expense on mandatorily redeemable capital stock from adjusted net interest income in its analysis of financial performance for its two operating segments