Statements of Changes in Capital - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Total capital, beginning balance	$ 3,818,842	$ 5,055,905	$ 4,472,836	$ 5,376,294
Comprehensive Income	83,980	60,168	202,307	266,840
Issuance of capital stock	225,546	1,578,013	2,706,902	4,863,370
Repurchase/redemption of capital stock	(716,595)	(1,848,336)	(3,842,070)	(5,156,630)
Net shares reclassified to mandatorily redeemable capital stock			(39,457)	(361,117)
Partial Recovery Of Prior Capital Distribution To Financing Corporation			8,541
Cash dividends	(39,795)	(60,100)	(137,194)	(203,107)
Total capital, ending balance	$ 3,371,978	$ 4,785,650	$ 3,371,978	$ 4,785,650
Capital Stock - Putable
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, shares beginning balance	23,714	36,432	30,550	40,272
Total capital, beginning balance	$ 2,371,420	$ 3,643,190	$ 3,054,996	$ 4,027,244
Issuance of capital stock, shares	2,256	15,780	27,069	48,634
Issuance of capital stock	$ 225,546	$ 1,578,013	$ 2,706,902	$ 4,863,370
Repurchase/redemption of capital stock, shares	(7,166)	(18,483)	(38,421)	(51,566)
Repurchase/redemption of capital stock	$ (716,595)	$ (1,848,336)	$ (3,842,070)	$ (5,156,630)
Net shares reclassified to mandatorily redeemable capital stock, shares			(394)	(3,611)
Net shares reclassified to mandatorily redeemable capital stock			$ (39,457)	$ (361,117)
Balance, shares ending balance	18,804	33,729	18,804	33,729
Total capital, ending balance	$ 1,880,371	$ 3,372,867	$ 1,880,371	$ 3,372,867
Retained Earnings, Unrestricted
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Total capital, beginning balance	898,980	913,555	910,726	924,001
Comprehensive Income	45,940	56,221	122,939	188,782
Partial Recovery Of Prior Capital Distribution To Financing Corporation			8,541
Cash dividends	(39,795)	(60,100)	(137,194)	(203,107)
Total capital, ending balance	905,125	909,676	905,125	909,676
Retained Earnings, Restricted
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Total capital, beginning balance	434,538	385,044	415,288	351,903
Comprehensive Income	11,485	14,055	30,735	47,196
Total capital, ending balance	446,023	399,099	446,023	399,099
Retained Earnings Total
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Total capital, beginning balance	1,333,518	1,298,599	1,326,014	1,275,904
Comprehensive Income	57,425	70,276	153,674	235,978
Partial Recovery Of Prior Capital Distribution To Financing Corporation			8,541
Cash dividends	(39,795)	(60,100)	(137,194)	(203,107)
Total capital, ending balance	1,351,148	1,308,775	1,351,148	1,308,775
Accumulated Other Comprehensive Income (Loss)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Total capital, beginning balance	113,904	114,116	91,826	73,146
Comprehensive Income	26,555	(10,108)	48,633	30,862
Total capital, ending balance	140,459	$ 104,008	140,459	$ 104,008
Accounting Standards Update 2016-13 [Member] | Cumulative Effect, Period of Adoption, Adjustment [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Total capital, ending balance	113		113
Accounting Standards Update 2016-13 [Member] | Cumulative Effect, Period of Adoption, Adjustment [Member] | Retained Earnings, Unrestricted
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Total capital, ending balance	113		113
Accounting Standards Update 2016-13 [Member] | Cumulative Effect, Period of Adoption, Adjustment [Member] | Retained Earnings Total
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Total capital, ending balance	113		113
Accounting Standards Update 2016-13 [Member] | Cumulative Effect, Period of Adoption, Adjustment [Member] | Accumulated Other Comprehensive Income (Loss)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Total capital, ending balance	$ 0		$ 0