Segment Reporting (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Segment Reporting Information [Line Items]
Net interest income	$ 5,150	$ 5,377	$ 9,883	$ 10,609
Fee and other income	246	239	473	559
Net revenues	5,396	5,616	10,356	11,168
Investment gains, net	461	277	594	527
Fair value gains (losses), net	(754)	229	(1,585)	1,274
Administrative expenses	(744)	(755)	(1,488)	(1,505)
Benefit (provision) for credit losses	1,225	1,296	1,875	1,513
Foreclosed property income (expense)	(128)	(139)	(268)	(301)
Total credit-related income (expense)	1,097	1,157	1,607	1,212
Temporary Payroll Tax Cut Continuation Act of 2011 (“TCCA”) fees	(600)	(565)	(1,193)	(1,122)
Other expenses, net	(535)	(366)	(943)	(569)
Income before federal income taxes	4,321	5,593	7,348	10,985
Provision for federal income taxes	(889)	(1,136)	(1,516)	(2,267)
Net income	3,432	4,457	5,832	8,718
US Treasury [Member]
Segment Reporting Information [Line Items]
Temporary Payroll Tax Cut Continuation Act of 2011 (“TCCA”) fees	(600)	(565)	(1,193)	(1,122)
Business Segments [Member] | Single-family [Member]
Segment Reporting Information [Line Items]
Net interest income	4,419	4,723	8,458	9,284
Fee and other income	88	69	194	227
Net revenues	4,507	4,792	8,652	9,511
Investment gains, net	417	252	511	494
Fair value gains (losses), net	(758)	278	(1,645)	1,312
Administrative expenses	(634)	(649)	(1,265)	(1,292)
Benefit (provision) for credit losses	1,252	1,295	1,913	1,491
Foreclosed property income (expense)	(126)	(136)	(269)	(298)
Total credit-related income (expense)	1,126	1,159	1,644	1,193
Other expenses, net	(418)	(270)	(755)	(402)
Income before federal income taxes	3,640	4,997	5,949	9,694
Provision for federal income taxes	(769)	(1,044)	(1,253)	(2,060)
Net income	2,871	3,953	4,696	7,634
Business Segments [Member] | Single-family [Member] | US Treasury [Member]
Segment Reporting Information [Line Items]
Temporary Payroll Tax Cut Continuation Act of 2011 (“TCCA”) fees	(600)	(565)	(1,193)	(1,122)
Business Segments [Member] | Multifamily [Member]
Segment Reporting Information [Line Items]
Net interest income	731	654	1,425	1,325
Fee and other income	158	170	279	332
Net revenues	889	824	1,704	1,657
Investment gains, net	44	25	83	33
Fair value gains (losses), net	4	(49)	60	(38)
Administrative expenses	(110)	(106)	(223)	(213)
Benefit (provision) for credit losses	(27)	1	(38)	22
Foreclosed property income (expense)	(2)	(3)	1	(3)
Total credit-related income (expense)	(29)	(2)	(37)	19
Other expenses, net	(117)	(96)	(188)	(167)
Income before federal income taxes	681	596	1,399	1,291
Provision for federal income taxes	(120)	(92)	(263)	(207)
Net income	561	504	1,136	1,084
Business Segments [Member] | Multifamily [Member] | US Treasury [Member]
Segment Reporting Information [Line Items]
Temporary Payroll Tax Cut Continuation Act of 2011 (“TCCA”) fees	$ 0	$ 0	$ 0	$ 0