Allowance for Loan Losses (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Financing Receivable, Allowance for Credit Loss [Line Items]
Beginning balance	$ (11,335)	$ (5,899)	$ (11,347)	$ (5,629)
Benefit (provision) for loan losses	1,247	(260)	1,071	(514)
Write-offs	70	248	349	275
Recoveries	(28)	(94)	(113)	(134)
Other	64	(64)	58	(67)
Ending balance	(9,982)	(6,069)	(9,982)	(6,069)
Single-family
Financing Receivable, Allowance for Credit Loss [Line Items]
Beginning balance	(9,479)	(5,241)	(9,443)	(4,950)
Benefit (provision) for loan losses	1,399	(248)	1,403	(530)
Write-offs	53	248	95	275
Recoveries	(27)	(84)	(103)	(117)
Other	64	(64)	58	(67)
Ending balance	(7,990)	(5,389)	(7,990)	(5,389)
Multifamily
Financing Receivable, Allowance for Credit Loss [Line Items]
Beginning balance	(1,856)	(658)	(1,904)	(679)
Benefit (provision) for loan losses	(152)	(12)	(332)	16
Write-offs	17	0	254	0
Recoveries	(1)	(10)	(10)	(17)
Ending balance	$ (1,992)	$ (680)	$ (1,992)	$ (680)