Allowance for Loan Losses (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Financing Receivable, Allowance for Credit Loss [Line Items]
Beginning balance	$ (9,982)	$ (6,069)	$ (11,347)	$ (5,629)
Benefit (provision) for loan losses	635	(2,508)	1,706	(3,022)
Write-offs	751	328	1,100	603
Recoveries	(56)	(69)	(169)	(203)
Other	(19)	16	39	(51)
Ending balance	(8,671)	(8,302)	(8,671)	(8,302)
Single-family
Financing Receivable, Allowance for Credit Loss [Line Items]
Amortized cost	3,122	1,726	3,122	6,099
Lower of cost or fair value adjustment at time of redesignation	(638)	(196)	(638)	(418)
Single-family
Financing Receivable, Allowance for Credit Loss [Line Items]
Beginning balance	(7,990)	(5,389)	(9,443)	(4,950)
Benefit (provision) for loan losses	718	(2,339)	2,121	(2,869)
Write-offs	699	289	794	564
Recoveries	(48)	(65)	(151)	(182)
Other	(19)	16	39	(51)
Ending balance	(6,640)	(7,488)	(6,640)	(7,488)
Multifamily
Financing Receivable, Allowance for Credit Loss [Line Items]
Beginning balance	(1,992)	(680)	(1,904)	(679)
Benefit (provision) for loan losses	(83)	(169)	(415)	(153)
Write-offs	52	39	306	39
Recoveries	(8)	(4)	(18)	(21)
Ending balance	$ (2,031)	$ (814)	$ (2,031)	$ (814)