Mortgage Loans - Nonaccrual Loans (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Financing Receivable, Nonaccrual [Line Items]
Amortized cost, nonaccrual loans	$ 29,101	$ 25,205	$ 12,517	$ 20,496
Interest income recognized, nonaccrual loans	560	441	298
Single-family
Financing Receivable, Nonaccrual [Line Items]
Accrued interest receivable written off	391	325	61
Amortized cost, nonaccrual loans	26,584	23,315	10,317	19,237
Interest income recognized, nonaccrual loans	505	400	223
Single-family | 20- and 30-year or more, amortizing fixed-rate
Financing Receivable, Nonaccrual [Line Items]
Amortized cost, nonaccrual loans	25,218	21,971	9,447	17,599
Interest income recognized, nonaccrual loans	481	379	207
Single-family | 15-year or less, amortizing fixed-rate
Financing Receivable, Nonaccrual [Line Items]
Amortized cost, nonaccrual loans	770	727	200	430
Interest income recognized, nonaccrual loans	11	9	4
Single-family | Adjustable-rate
Financing Receivable, Nonaccrual [Line Items]
Amortized cost, nonaccrual loans	114	109	53	107
Interest income recognized, nonaccrual loans	3	2	1
Single-family | Other
Financing Receivable, Nonaccrual [Line Items]
Amortized cost, nonaccrual loans	482	508	617	1,101
Interest income recognized, nonaccrual loans	10	10	11
Multifamily
Financing Receivable, Nonaccrual [Line Items]
Accrued interest receivable written off	32	49	1
Amortized cost, nonaccrual loans	2,517	1,890	2,200	$ 1,259
Interest income recognized, nonaccrual loans	$ 55	$ 41	$ 75