Allowance for Loan Losses (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Financing Receivable, Allowance for Credit Loss [Line Items]
Beginning balance	$ (11,347)	$ (5,629)
Benefit (provision) for loan losses	(176)	(254)
Write-offs	279	27
Recoveries	(85)	(40)
Other	(6)	(3)
Ending balance	(11,335)	(5,899)
Single-family
Financing Receivable, Allowance for Credit Loss [Line Items]
Beginning balance	(9,443)	(4,950)
Benefit (provision) for loan losses	4	(282)
Write-offs	42	27
Recoveries	(76)	(33)
Other	(6)	(3)
Ending balance	(9,479)	(5,241)
Multifamily
Financing Receivable, Allowance for Credit Loss [Line Items]
Beginning balance	(1,904)	(679)
Benefit (provision) for loan losses	(180)	28
Write-offs	237	0
Recoveries	(9)	(7)
Ending balance	$ (1,856)	$ (658)