Mortgage Loans - Loans in Mortgage Portfolio (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021	Mar. 31, 2022	Dec. 31, 2021	Mar. 31, 2021	Dec. 31, 2020
Loans in Mortgage Portfolio [Line Items]
Total unpaid principal balance of mortgage loans	$ 4,039,745		$ 4,039,745			$ 3,899,025
Cost basis and fair value adjustments, net	58,255		58,255			74,846
Allowance for loan losses for HFI loans	(6,069)	$ (7,114)	(6,069)	$ (7,114)	$ (5,899)	(5,629)	$ (9,628)	$ (10,552)
Total mortgage loans	4,091,931		4,091,931			3,968,242
Single-family
Loans in Mortgage Portfolio [Line Items]
Total unpaid principal balance of mortgage loans	3,623,404		3,623,404			3,495,573
Amortized cost	3,192	6,305	4,373	9,417
Lower of cost or fair value adjustment at time of redesignation	(209)	(146)	(222)	(200)
Allowance reversed at time of redesignation	155	824	218	1,185
Unpaid principal balance	4,310	7,317	4,310	7,525
Realized gains, net	71	$ 653	71	$ 655
Mortgage loans in process of foreclosure	4,600		4,600			4,400
Multifamily
Loans in Mortgage Portfolio [Line Items]
Total unpaid principal balance of mortgage loans	416,341		416,341			403,452
Mortgage loans
Loans in Mortgage Portfolio [Line Items]
Accrued interest receivable	$ 9,400		$ 9,400			$ 9,100