Mortgage Loans - Nonaccrual Loans (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Amortized cost, nonaccrual loans	$ 20,496	$ 28,574	$ 27,981
Interest income recognized, nonaccrual loans	328	583
Single-family
Accrued interest receivable written off	163	206
Amortized cost, nonaccrual loans	19,237	26,505	27,546
Interest income recognized, nonaccrual loans	314	524
Single-family | 20- and 30-year or more, amortizing fixed-rate
Amortized cost, nonaccrual loans	17,599	22,907	23,427
Interest income recognized, nonaccrual loans	292	461
Single-family | 15-year or less, amortizing fixed-rate
Amortized cost, nonaccrual loans	430	853	858
Interest income recognized, nonaccrual loans	6	15
Single-family | Adjustable-rate
Amortized cost, nonaccrual loans	107	270	288
Interest income recognized, nonaccrual loans	1	5
Single-family | Other
Amortized cost, nonaccrual loans	1,101	2,475	2,973
Interest income recognized, nonaccrual loans	15	43
Multifamily
Accrued interest receivable written off	1	19
Amortized cost, nonaccrual loans	1,259	2,069	$ 435
Interest income recognized, nonaccrual loans	$ 14	$ 59