Mortgage Loans - Loans in Mortgage Portfolio (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Jun. 30, 2023	Dec. 31, 2022	Jun. 30, 2022	Dec. 31, 2021
Loans in Mortgage Portfolio [Line Items]
Total unpaid principal balance of mortgage loans	$ 4,100,280		$ 4,100,280			$ 4,075,598
Cost basis and fair value adjustments, net	42,279		42,279			50,185
Allowance for loan losses for HFI loans	(8,671)	$ (8,302)	(8,671)	$ (8,302)	$ (9,982)	(11,347)	$ (6,069)	$ (5,629)
Total mortgage loans	4,133,888		4,133,888			4,114,436
Accrued interest receivable	10,462		10,462			9,821
Single-family
Loans in Mortgage Portfolio [Line Items]
Total unpaid principal balance of mortgage loans	3,644,725		3,644,725			3,644,158
Purchase of HFI loans:	89,228	117,686	245,870	529,453
Amortized cost	3,122	1,726	3,122	6,099
Lower of cost or fair value adjustment at time of redesignation	(638)	(196)	(638)	(418)
Allowance reversed at time of redesignation	47	80	47	298
Amortized cost	372	1	372	1
Unpaid principal balance	0	1,919	1,842	6,229
Realized gains, net	0	20	17	91
Mortgage loans in process of foreclosure	4,600		4,600			4,600
Multifamily
Loans in Mortgage Portfolio [Line Items]
Total unpaid principal balance of mortgage loans	455,555		455,555			431,440
Purchase of HFI loans:	16,415	$ 15,943	41,761	$ 50,627
Mortgage loans
Loans in Mortgage Portfolio [Line Items]
Accrued interest receivable	$ 10,100		$ 10,100			$ 9,500