Allowance for Loan Losses (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Financing Receivable, Allowance for Credit Loss [Line Items]
Beginning balance	$ (6,069)	$ (7,114)	$ (5,629)	$ (10,552)
Benefit (provision) for loan losses	(2,508)	884	(3,022)	4,178
Write-offs	328	58	603	325
Recoveries	(69)	(154)	(203)	(252)
Other	16	(8)	(51)	(33)
Ending Balance	(8,302)	(6,334)	(8,302)	(6,334)
Single-family
Financing Receivable, Allowance for Credit Loss [Line Items]
Beginning balance	(5,389)	(6,064)	(4,950)	(9,344)
Benefit (provision) for loan losses	(2,339)	839	(2,869)	4,003
Write-offs	289	51	564	271
Recoveries	(65)	(133)	(182)	(212)
Other	16	(8)	(51)	(33)
Ending Balance	(7,488)	(5,315)	(7,488)	(5,315)
Multifamily
Financing Receivable, Allowance for Credit Loss [Line Items]
Beginning balance	(680)	(1,050)	(679)	(1,208)
Benefit (provision) for loan losses	(169)	45	(153)	175
Write-offs	39	7	39	54
Recoveries	(4)	(21)	(21)	(40)
Ending Balance	$ (814)	$ (1,019)	$ (814)	$ (1,019)