Mortgage Loans - Non-accrual Loans (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021	Jun. 30, 2022	Dec. 31, 2021	Jun. 30, 2021	Dec. 31, 2020
Financing Receivable, Nonaccrual [Line Items]
Recorded investment in nonaccrual loans	$ 12,233	$ 24,230	$ 12,233	$ 24,230	$ 12,560	$ 20,496	$ 29,484	$ 28,574
Total interest income recognized	64	80	213	284
Single-family
Financing Receivable, Nonaccrual [Line Items]
Accrued interest receivable written off through the reversal of interest income:	14	15	46	144
Recorded investment in nonaccrual loans	11,002	21,977	11,002	21,977	11,243	19,237	27,264	26,505
Total interest income recognized	52	71	188	260
Single-family | 20- and 30-year or more, amortizing fixed-rate
Financing Receivable, Nonaccrual [Line Items]
Recorded investment in nonaccrual loans	10,121	20,083	10,121	20,083	10,241	17,599	24,728	22,907
Total interest income recognized	48	67	175	241
Single-family | 15-year or less, amortizing fixed-rate
Financing Receivable, Nonaccrual [Line Items]
Recorded investment in nonaccrual loans	235	491	235	491	245	430	596	853
Total interest income recognized	1	1	3	4
Single-family | Adjustable-rate
Financing Receivable, Nonaccrual [Line Items]
Recorded investment in nonaccrual loans	55	126	55	126	59	107	179	270
Total interest income recognized	0	0	1	1
Single-family | Other
Financing Receivable, Nonaccrual [Line Items]
Recorded investment in nonaccrual loans	591	1,277	591	1,277	698	1,101	1,761	2,475
Total interest income recognized	3	3	9	14
Multifamily
Financing Receivable, Nonaccrual [Line Items]
Accrued interest receivable written off through the reversal of interest income:	1	0	1	1
Recorded investment in nonaccrual loans	1,231	2,253	1,231	2,253	$ 1,317	$ 1,259	$ 2,220	$ 2,069
Total interest income recognized	$ 12	$ 9	$ 25	$ 24