Segment Reporting (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Segment Reporting Information [Line Items]
Net interest income	$ 5,232	$ 5,346
Fee and other income	320	249
Net revenues	5,552	5,595
Investment gains (losses), net	250	(9)
Fair value gains (losses), net	1,045	(40)
Administrative expenses	(750)	(684)
Benefit (provision) for credit losses	217	396
Foreclosed property income (expense)	(162)	(217)
Total credit-related income (expense)	55	179
Temporary Payroll Tax Cut Continuation Act of 2011 (“TCCA”) fees	(557)	(503)
Other expenses, net	(203)	(382)
Income before federal income taxes	5,392	4,156
Provision for federal income taxes	(1,131)	(1,383)
Net income	4,261	2,773
US Treasury [Member]
Segment Reporting Information [Line Items]
Temporary Payroll Tax Cut Continuation Act of 2011 (“TCCA”) fees	(557)	(503)
Business Segments [Member] | Single-family [Member]
Segment Reporting Information [Line Items]
Net interest income	4,561	4,756
Fee and other income	158	76
Net revenues	4,719	4,832
Investment gains (losses), net	242	(50)
Fair value gains (losses), net	1,034	(12)
Administrative expenses	(643)	(601)
Benefit (provision) for credit losses	196	400
Foreclosed property income (expense)	(162)	(216)
Total credit-related income (expense)	34	184
Other expenses, net	(132)	(256)
Income before federal income taxes	4,697	3,594
Provision for federal income taxes	(1,016)	(1,252)
Net income	3,681	2,342
Business Segments [Member] | Single-family [Member] | US Treasury [Member]
Segment Reporting Information [Line Items]
Temporary Payroll Tax Cut Continuation Act of 2011 (“TCCA”) fees	(557)	(503)
Business Segments [Member] | Multifamily [Member]
Segment Reporting Information [Line Items]
Net interest income	671	590
Fee and other income	162	173
Net revenues	833	763
Investment gains (losses), net	8	41
Fair value gains (losses), net	11	(28)
Administrative expenses	(107)	(83)
Benefit (provision) for credit losses	21	(4)
Foreclosed property income (expense)	0	(1)
Total credit-related income (expense)	21	(5)
Other expenses, net	(71)	(126)
Income before federal income taxes	695	562
Provision for federal income taxes	(115)	(131)
Net income	$ 580	$ 431