Mortgage Loans - Loans in Mortgage Portfolio (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022	Mar. 31, 2023	Dec. 31, 2022	Mar. 31, 2022	Dec. 31, 2021
Loans in Mortgage Portfolio [Line Items]
Total unpaid principal balance of mortgage loans	$ 4,084,539		$ 4,084,539			$ 4,075,598
Cost basis and fair value adjustments, net	46,568		46,568			50,185
Allowance for loan losses for HFI loans	(9,982)	$ (6,069)	(9,982)	$ (6,069)	$ (11,335)	(11,347)	$ (5,899)	$ (5,629)
Total mortgage loans	4,121,125		4,121,125			4,114,436
Accrued interest receivable	9,930		9,930			9,821
Single-family
Loans in Mortgage Portfolio [Line Items]
Total unpaid principal balance of mortgage loans	3,638,886		3,638,886			3,644,158
Purchase of HFI loans:	89,175	172,303	156,642	411,771
Amortized cost	0	3,192	0	4,373
Lower of cost or fair value adjustment at time of redesignation	0	(209)	0	(222)
Allowance reversed at time of redesignation	0	155	0	218
Unpaid principal balance	0	4,310	1,842	4,310
Realized gains, net	0	71	17	71
Mortgage loans in process of foreclosure	4,500		4,500			4,600
Multifamily
Loans in Mortgage Portfolio [Line Items]
Total unpaid principal balance of mortgage loans	445,653		445,653			431,440
Purchase of HFI loans:	15,111	$ 18,674	25,346	$ 34,683
Mortgage loans
Loans in Mortgage Portfolio [Line Items]
Accrued interest receivable	$ 9,700		$ 9,700			$ 9,500