Capital Requirements (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Stockholders' Equity Note [Abstract]
Capital-to-asset ratio, Required	4.00%	4.00%
Leverage capital-to-assets ratio, Required	5.00%	5.00%
Multiplier for Determining Permanent Capital in Leverage Capital Calculation	1.5
Class B capital stock	$ 1,869,130	$ 2,528,854
Mandatorily redeemable capital stock	5,806	31,868	$ 35,923	$ 32,687
Retained earnings	1,463,154	1,395,012
Total permanent capital	3,338,090	3,955,734
Credit-risk capital	235,213	289,080
Market-risk capital	207,426	187,183
Operations-risk capital	132,792	142,879
Total risk-based capital requirement	575,431	619,142
Permanent capital in excess of risk-based capital requirement	2,762,659	3,336,592
Regulatory capital, Required	2,226,512	2,543,733
Leverage capital, Required	2,783,141	3,179,666
Risk-based capital, Actual	3,338,090	3,955,734
Regulatory capital, Actual	$ 3,338,090	$ 3,955,734
Capital-to-asset ratio, Actual	6.00%	6.20%
Leverage capital, Actual	$ 5,007,135	$ 5,933,601
Leverage capital-to-assets ratio, Actual	9.00%	9.30%
Contribution requirement - Restricted Retained Earnings	$ 502,400
Restricted retained earnings	$ 348,817	$ 310,670