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Mortgage Loans - Nonaccrual Loans (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025	Mar. 31, 2026	Dec. 31, 2025	Mar. 31, 2025	Dec. 31, 2024
Financing Receivable, Nonaccrual [Line Items]
Amortized Cost	$ 31,419	$ 29,563	$ 31,419	$ 29,563	$ 31,734	$ 30,760	$ 30,393	$ 29,101
Total interest income recognized	61	64	173	162
Single-family
Financing Receivable, Nonaccrual [Line Items]
Accrued interest receivable written off through the reversal of interest income:	107	91	223	194
Amortized Cost	28,328	26,701	28,328	26,701	28,359	27,448	27,691	26,584
Total interest income recognized	55	58	162	155
Single-family \| 20- and 30-year or more, amortizing fixed-rate
Financing Receivable, Nonaccrual [Line Items]
Amortized Cost	27,139	25,423	27,139	25,423	27,148	26,221	26,335	25,218
Total interest income recognized	53	56	155	148
Single-family \| 15-year or less, amortizing fixed-rate
Financing Receivable, Nonaccrual [Line Items]
Amortized Cost	680	736	680	736	681	692	771	770
Total interest income recognized	1	1	3	3
Single-family \| Adjustable-rate
Financing Receivable, Nonaccrual [Line Items]
Amortized Cost	111	114	111	114	118	114	122	114
Total interest income recognized	0	0	1	1
Single-family \| Other
Financing Receivable, Nonaccrual [Line Items]
Amortized Cost	398	428	398	428	412	421	463	482
Total interest income recognized	1	1	3	3
Multifamily
Financing Receivable, Nonaccrual [Line Items]
Accrued interest receivable written off through the reversal of interest income:	6	9	14	17
Amortized Cost	3,091	2,862	3,091	2,862	$ 3,375	$ 3,312	$ 2,702	$ 2,517
Total interest income recognized	$ 6	$ 6	$ 11	$ 7