Capital (Mandatorily Redeemable Capital Stock) (Details) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020 USD ($) Institutions $ / shares	Sep. 30, 2019 USD ($)	Sep. 30, 2020 USD ($) Institutions $ / shares	Sep. 30, 2019 USD ($)	Dec. 31, 2019 $ / shares
Banking Regulation, Total Capital [Abstract]
Interest Expense, Capital Securities	$ 4,100	$ 6,700	$ 14,100	$ 10,600
Balance, beginning of the period			343,575	24,099
Capital stock subject to mandatory redemption reclassified from capital			39,457	361,117
Redemption/repurchase of mandatorily redeemable stock			(159,980)	(41,505)
Balance, end of the period	$ 223,052	$ 343,711	$ 223,052	$ 343,711
Capital stock, Par value Per Share | $ / shares	$ 100		$ 100		$ 100
Financial Instruments Subject to Mandatory Redemption, Number of Institutions | Institutions	6		6
Financial Instruments Subject to Mandatory Redemption, Due to Institution Mergers | Institutions	4		4
Financial instruments subject to mandatory redemption, due to relocation | Institutions	1		1
Financial Instruments Subject to Mandatory Redemption, Number of Institutions, Voluntary Withdrawls | Institutions	1		1