Mortgage Loans - Loans in Mortgage Portfolio (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023	Mar. 31, 2024	Dec. 31, 2023	Mar. 31, 2023	Dec. 31, 2022
Loans in Mortgage Portfolio [Line Items]
Total unpaid principal balance of mortgage loans	$ 4,098,304		$ 4,098,304			$ 4,102,632
Cost basis and fair value adjustments, net	38,936		38,936			41,729
Allowance for loan losses for HFI loans	(8,026)	$ (9,982)	(8,026)	$ (9,982)	$ (8,379)	(8,730)	$ (11,335)	$ (11,347)
Total mortgage loans	4,129,214		4,129,214			4,135,631
Accrued interest receivable, net	11,156		11,156			10,724
Single-family
Loans in Mortgage Portfolio [Line Items]
Allowance for loan losses for HFI loans	(5,703)	(7,990)	(5,703)	(7,990)	$ (6,275)	(6,671)	$ (9,479)	$ (9,443)
Amortized cost			452
Lower of cost or fair value adjustment at time of redesignation			(38)
Allowance reversed at time of redesignation	4	0	3
Single-family
Loans in Mortgage Portfolio [Line Items]
Total unpaid principal balance of mortgage loans	3,627,376		3,627,376			3,641,385
Purchase of HFI loans:	85,776	89,175	148,066	156,642
Amortized cost	216	0		0
Lower of cost or fair value adjustment at time of redesignation	(18)	0		0
Allowance reversed at time of redesignation				0
Unpaid principal balance	1,832	0	2,331	1,842
Realized gains (losses), net	8	0	13	17
Mortgage loans in process of foreclosure	4,400		4,400			4,600
Multifamily
Loans in Mortgage Portfolio [Line Items]
Total unpaid principal balance of mortgage loans	470,928		470,928			461,247
Purchase of HFI loans:	9,271	$ 15,111	19,339	$ 25,346
Mortgage loans
Loans in Mortgage Portfolio [Line Items]
Accrued interest receivable, net	$ 10,800		$ 10,800			$ 10,400