Mortgage Loans - Aging (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2022	Dec. 31, 2021
Financing Receivable, Past Due [Line Items]
Recorded investment	$ 4,055,379	$ 3,973,024
Loans 90 Days or More Delinquent and Accruing Interest	21,834	27,302
Nonaccrual Loans with No Allowance	5,894	7,179
Total Delinquent
Financing Receivable, Past Due [Line Items]
Recorded investment	63,007	75,801
30 - 59 Days Delinquent
Financing Receivable, Past Due [Line Items]
Recorded investment	21,948	25,947
60 - 89 Days Delinquent
Financing Receivable, Past Due [Line Items]
Recorded investment	5,800	5,758
Seriously Delinquent
Financing Receivable, Past Due [Line Items]
Recorded investment	35,259	44,096
Current
Financing Receivable, Past Due [Line Items]
Recorded investment	3,992,372	3,897,223
Single-family
Financing Receivable, Past Due [Line Items]
Recorded investment	3,642,912	3,566,819
Loans 90 Days or More Delinquent and Accruing Interest	21,640	26,985
Nonaccrual Loans with No Allowance	$ 5,796	$ 7,072
Single-family | Minimum
Table Footnote [Abstract]
Serious delinquency, days past due	90 days	90 days
Single-family | Total Delinquent
Financing Receivable, Past Due [Line Items]
Recorded investment	$ 61,377	$ 73,994
Single-family | 30 - 59 Days Delinquent
Financing Receivable, Past Due [Line Items]
Recorded investment	21,876	25,833
Single-family | 60 - 89 Days Delinquent
Financing Receivable, Past Due [Line Items]
Recorded investment	5,800	5,758
Single-family | Seriously Delinquent
Financing Receivable, Past Due [Line Items]
Recorded investment	33,701	42,403
Single-family | Current
Financing Receivable, Past Due [Line Items]
Recorded investment	3,581,535	3,492,825
Single-family | 20- and 30-year or more, amortizing fixed-rate
Financing Receivable, Past Due [Line Items]
Recorded investment	3,046,100	2,969,105
Loans 90 Days or More Delinquent and Accruing Interest	19,646	24,236
Nonaccrual Loans with No Allowance	5,135	6,271
Single-family | 20- and 30-year or more, amortizing fixed-rate | Total Delinquent
Financing Receivable, Past Due [Line Items]
Recorded investment	55,495	66,342
Single-family | 20- and 30-year or more, amortizing fixed-rate | 30 - 59 Days Delinquent
Financing Receivable, Past Due [Line Items]
Recorded investment	19,604	22,862
Single-family | 20- and 30-year or more, amortizing fixed-rate | 60 - 89 Days Delinquent
Financing Receivable, Past Due [Line Items]
Recorded investment	5,276	5,192
Single-family | 20- and 30-year or more, amortizing fixed-rate | Seriously Delinquent
Financing Receivable, Past Due [Line Items]
Recorded investment	30,615	38,288
Single-family | 20- and 30-year or more, amortizing fixed-rate | Current
Financing Receivable, Past Due [Line Items]
Recorded investment	2,990,605	2,902,763
Single-family | 15-year or less, amortizing fixed-rate
Financing Receivable, Past Due [Line Items]
Recorded investment	534,794	533,427
Loans 90 Days or More Delinquent and Accruing Interest	1,061	1,454
Nonaccrual Loans with No Allowance	147	193
Single-family | 15-year or less, amortizing fixed-rate | Total Delinquent
Financing Receivable, Past Due [Line Items]
Recorded investment	3,155	4,149
Single-family | 15-year or less, amortizing fixed-rate | 30 - 59 Days Delinquent
Financing Receivable, Past Due [Line Items]
Recorded investment	1,532	2,024
Single-family | 15-year or less, amortizing fixed-rate | 60 - 89 Days Delinquent
Financing Receivable, Past Due [Line Items]
Recorded investment	300	326
Single-family | 15-year or less, amortizing fixed-rate | Seriously Delinquent
Financing Receivable, Past Due [Line Items]
Recorded investment	1,323	1,799
Single-family | 15-year or less, amortizing fixed-rate | Current
Financing Receivable, Past Due [Line Items]
Recorded investment	531,639	529,278
Single-family | Adjustable-rate
Financing Receivable, Past Due [Line Items]
Recorded investment	26,191	26,342
Loans 90 Days or More Delinquent and Accruing Interest	198	287
Nonaccrual Loans with No Allowance	55	63
Single-family | Adjustable-rate | Total Delinquent
Financing Receivable, Past Due [Line Items]
Recorded investment	448	571
Single-family | Adjustable-rate | 30 - 59 Days Delinquent
Financing Receivable, Past Due [Line Items]
Recorded investment	146	161
Single-family | Adjustable-rate | 60 - 89 Days Delinquent
Financing Receivable, Past Due [Line Items]
Recorded investment	36	36
Single-family | Adjustable-rate | Seriously Delinquent
Financing Receivable, Past Due [Line Items]
Recorded investment	266	374
Single-family | Adjustable-rate | Current
Financing Receivable, Past Due [Line Items]
Recorded investment	25,743	25,771
Single-family | Other
Financing Receivable, Past Due [Line Items]
Recorded investment	35,827	37,945
Loans 90 Days or More Delinquent and Accruing Interest	735	1,008
Nonaccrual Loans with No Allowance	459	545
Single-family | Other | Total Delinquent
Financing Receivable, Past Due [Line Items]
Recorded investment	2,279	2,932
Single-family | Other | 30 - 59 Days Delinquent
Financing Receivable, Past Due [Line Items]
Recorded investment	594	786
Single-family | Other | 60 - 89 Days Delinquent
Financing Receivable, Past Due [Line Items]
Recorded investment	188	204
Single-family | Other | Seriously Delinquent
Financing Receivable, Past Due [Line Items]
Recorded investment	1,497	1,942
Single-family | Other | Current
Financing Receivable, Past Due [Line Items]
Recorded investment	33,548	35,013
Multifamily
Financing Receivable, Past Due [Line Items]
Recorded investment	412,467	406,205
Loans 90 Days or More Delinquent and Accruing Interest	194	317
Nonaccrual Loans with No Allowance	$ 98	107
Multifamily | Minimum
Table Footnote [Abstract]
Serious delinquency, days past due	60 days
Multifamily | Total Delinquent
Financing Receivable, Past Due [Line Items]
Recorded investment	$ 1,630	1,807
Multifamily | 30 - 59 Days Delinquent
Financing Receivable, Past Due [Line Items]
Recorded investment	72	114
Multifamily | Seriously Delinquent
Financing Receivable, Past Due [Line Items]
Recorded investment	1,558	1,693
Multifamily | Current
Financing Receivable, Past Due [Line Items]
Recorded investment	$ 410,837	$ 404,398