Mortgage Loans - Nonaccrual Loans (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2026	Sep. 30, 2025	Sep. 30, 2026	Sep. 30, 2025	Jun. 30, 2026	Dec. 31, 2025	Jun. 30, 2025	Dec. 31, 2024
Financing Receivable, Nonaccrual [Line Items]
Amortized Cost	$ 31,969	$ 29,035	$ 31,969	$ 29,035	$ 31,419	$ 30,760	$ 29,563	$ 29,101
Total interest income recognized	48	52	373	331
Single-family
Financing Receivable, Nonaccrual [Line Items]
Accrued interest receivable written off through the reversal of interest income:	125	101	348	295
Amortized Cost	28,912	26,141	28,912	26,141	28,328	27,448	26,701	26,584
Total interest income recognized	42	47	350	308
Single-family | 20- and 30-year or more, amortizing fixed-rate
Financing Receivable, Nonaccrual [Line Items]
Amortized Cost	27,753	24,936	27,753	24,936	27,139	26,221	25,423	25,218
Total interest income recognized	40	45	337	295
Single-family | 15-year or less, amortizing fixed-rate
Financing Receivable, Nonaccrual [Line Items]
Amortized Cost	672	689	672	689	680	692	736	770
Total interest income recognized	1	1	6	6
Single-family | Adjustable-rate
Financing Receivable, Nonaccrual [Line Items]
Amortized Cost	114	108	114	108	111	114	114	114
Total interest income recognized	0	0	2	2
Single-family | Other
Financing Receivable, Nonaccrual [Line Items]
Amortized Cost	373	408	373	408	398	421	428	482
Total interest income recognized	1	1	5	5
Multifamily
Financing Receivable, Nonaccrual [Line Items]
Accrued interest receivable written off through the reversal of interest income:	9	11	19	25
Amortized Cost	3,057	2,894	3,057	2,894	$ 3,091	$ 3,312	$ 2,862	$ 2,517
Total interest income recognized	$ 6	$ 5	$ 23	$ 23