Mortgage Loans - Aging (Details) - USD ($) $ in Millions	6 Months Ended	9 Months Ended
	Jun. 30, 2022	Sep. 30, 2022	Dec. 31, 2021
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option		$ 4,114,465	$ 3,973,024
Loans 90 Days or More Delinquent and Accruing Interest		13,728	27,302
Nonaccrual Loans with No Allowance		$ 3,982	7,179
Table Footnote [Abstract]
Serious delinquency, days past due		90 days
Total Delinquent
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option		$ 53,792	75,801
30 - 59 Days Delinquent
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option		25,355	25,947
60 - 89 Days Delinquent
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option		6,061	5,758
Seriously Delinquent
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option		22,376	44,096
Current
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option		4,060,673	3,897,223
Single-family
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option		3,692,884	3,566,819
Loans 90 Days or More Delinquent and Accruing Interest		13,722	26,985
Nonaccrual Loans with No Allowance		$ 3,968	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]
Loans held for investment, excluding fair value option		$ 52,464	73,994
Single-family | 30 - 59 Days Delinquent
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option		25,073	25,833
Single-family | 60 - 89 Days Delinquent
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option		6,061	5,758
Single-family | Seriously Delinquent
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option		21,330	42,403
Single-family | Current
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option		3,640,420	3,492,825
Single-family | 20- and 30-year or more, amortizing fixed-rate
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option		3,127,133	2,969,105
Loans 90 Days or More Delinquent and Accruing Interest		12,525	24,236
Nonaccrual Loans with No Allowance		3,563	6,271
Single-family | 20- and 30-year or more, amortizing fixed-rate | Total Delinquent
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option		47,906	66,342
Single-family | 20- and 30-year or more, amortizing fixed-rate | 30 - 59 Days Delinquent
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option		22,792	22,862
Single-family | 20- and 30-year or more, amortizing fixed-rate | 60 - 89 Days Delinquent
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option		5,603	5,192
Single-family | 20- and 30-year or more, amortizing fixed-rate | Seriously Delinquent
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option		19,511	38,288
Single-family | 20- and 30-year or more, amortizing fixed-rate | Current
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option		3,079,227	2,902,763
Single-family | 15-year or less, amortizing fixed-rate
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option		507,222	533,427
Loans 90 Days or More Delinquent and Accruing Interest		654	1,454
Nonaccrual Loans with No Allowance		95	193
Single-family | 15-year or less, amortizing fixed-rate | Total Delinquent
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option		2,602	4,149
Single-family | 15-year or less, amortizing fixed-rate | 30 - 59 Days Delinquent
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option		1,530	2,024
Single-family | 15-year or less, amortizing fixed-rate | 60 - 89 Days Delinquent
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option		264	326
Single-family | 15-year or less, amortizing fixed-rate | Seriously Delinquent
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option		808	1,799
Single-family | 15-year or less, amortizing fixed-rate | Current
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option		504,620	529,278
Single-family | Adjustable-rate
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option		26,472	26,342
Loans 90 Days or More Delinquent and Accruing Interest		99	287
Nonaccrual Loans with No Allowance		28	63
Single-family | Adjustable-rate | Total Delinquent
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option		311	571
Single-family | Adjustable-rate | 30 - 59 Days Delinquent
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option		147	161
Single-family | Adjustable-rate | 60 - 89 Days Delinquent
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option		29	36
Single-family | Adjustable-rate | Seriously Delinquent
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option		135	374
Single-family | Adjustable-rate | Current
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option		26,161	25,771
Single-family | Other
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option		32,057	37,945
Loans 90 Days or More Delinquent and Accruing Interest		444	1,008
Nonaccrual Loans with No Allowance		282	545
Single-family | Other | Total Delinquent
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option		1,645	2,932
Single-family | Other | 30 - 59 Days Delinquent
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option		604	786
Single-family | Other | 60 - 89 Days Delinquent
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option		165	204
Single-family | Other | Seriously Delinquent
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option		876	1,942
Single-family | Other | Current
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option		30,412	35,013
Multifamily
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option		421,581	406,205
Loans 90 Days or More Delinquent and Accruing Interest		6	317
Nonaccrual Loans with No Allowance		$ 14	107
Multifamily | Minimum
Table Footnote [Abstract]
Serious delinquency, days past due		60 days
Multifamily | Total Delinquent
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option		$ 1,328	1,807
Multifamily | 30 - 59 Days Delinquent
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option		282	114
Multifamily | Seriously Delinquent
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option		1,046	1,693
Multifamily | Current
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option		$ 420,253	$ 404,398