Mortgage Loans - Non-accrual Loans (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021	Dec. 31, 2020
Financing Receivable, Nonaccrual [Line Items]
Recorded investment in nonaccrual loans	$ 16,278	$ 36,138	$ 20,496	$ 28,574
Total interest income recognized	56	79
Single-family
Financing Receivable, Nonaccrual [Line Items]
Accrued interest receivable written off through the reversal of interest income:	17	108
Recorded investment in nonaccrual loans	15,020	33,985	19,237	26,505
Total interest income recognized	51	71
Single-family | 20- and 30-year or more, amortizing fixed-rate
Financing Receivable, Nonaccrual [Line Items]
Recorded investment in nonaccrual loans	13,692	30,173	17,599	22,907
Total interest income recognized	47	64
Single-family | 15-year or less, amortizing fixed-rate
Financing Receivable, Nonaccrual [Line Items]
Recorded investment in nonaccrual loans	331	945	430	853
Total interest income recognized	1	2
Single-family | Adjustable-rate
Financing Receivable, Nonaccrual [Line Items]
Recorded investment in nonaccrual loans	84	284	107	270
Total interest income recognized	0	1
Single-family | Other
Financing Receivable, Nonaccrual [Line Items]
Recorded investment in nonaccrual loans	913	2,583	1,101	2,475
Total interest income recognized	3	4
Multifamily
Financing Receivable, Nonaccrual [Line Items]
Accrued interest receivable written off through the reversal of interest income:	1	0
Recorded investment in nonaccrual loans	1,258	2,153	$ 1,259	$ 2,069
Total interest income recognized	$ 5	$ 8