Mortgage Loans - Aging Analysis (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option	$ 4,149,258	$ 4,129,751
Loans 90 Days or More Delinquent and Accruing Interest	1,775	14,448
Nonaccrual Loans with No Allowance	$ 4,476	3,697
Table Footnote
Serious delinquency: days past due	90 days
Total Delinquent
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option	$ 66,479	60,877
30-59 Days Delinquent
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option	36,184	30,802
60 - 89 Days Delinquent
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option	8,625	7,305
Seriously Delinquent
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option	21,670	22,770
Current
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option	4,082,779	4,068,874
Single-family
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option	3,687,904	3,697,529
Loans 90 Days or More Delinquent and Accruing Interest	1,604	14,437
Nonaccrual Loans with No Allowance	$ 3,882	$ 3,684
Single-family | Minimum
Table Footnote
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	$ 64,331	$ 59,749
Single-family | 30-59 Days Delinquent
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option	35,735	30,629
Single-family | 60 - 89 Days Delinquent
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option	8,625	7,305
Single-family | Seriously Delinquent
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option	19,971	21,815
Single-family | Current
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option	3,623,573	3,637,780
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	3,208,042	3,146,854
Loans 90 Days or More Delinquent and Accruing Interest	1,371	13,257
Nonaccrual Loans with No Allowance	3,457	3,254
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	59,871	54,655
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	33,119	27,891
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	8,093	6,774
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	18,659	19,990
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	3,148,171	3,092,199
Single-family | 15-year or less, amortizing fixed-rate
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option	428,413	491,468
Loans 90 Days or More Delinquent and Accruing Interest	74	666
Nonaccrual Loans with No Allowance	176	82
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	2,815	3,016
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	1,846	1,902
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	319	314
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	650	800
Single-family | 15-year or less, amortizing fixed-rate | Current
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option	425,598	488,452
Single-family | Adjustable-rate
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option	26,358	27,108
Loans 90 Days or More Delinquent and Accruing Interest	11	90
Nonaccrual Loans with No Allowance	21	24
Single-family | Adjustable-rate | Total Delinquent
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option	326	341
Single-family | Adjustable-rate | 30-59 Days Delinquent
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option	184	176
Single-family | Adjustable-rate | 60 - 89 Days Delinquent
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option	42	38
Single-family | Adjustable-rate | Seriously Delinquent
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option	100	127
Single-family | Adjustable-rate | Current
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option	26,032	26,767
Single-family | Other
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option	25,091	32,099
Loans 90 Days or More Delinquent and Accruing Interest	148	424
Nonaccrual Loans with No Allowance	228	324
Single-family | Other | Total Delinquent
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option	1,319	1,737
Single-family | Other | 30-59 Days Delinquent
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option	586	660
Single-family | Other | 60 - 89 Days Delinquent
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option	171	179
Single-family | Other | Seriously Delinquent
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option	562	898
Single-family | Other | Current
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option	23,772	30,362
Multifamily
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option	461,354	432,222
Loans 90 Days or More Delinquent and Accruing Interest	171	11
Nonaccrual Loans with No Allowance	$ 594	$ 13
Multifamily | Minimum
Table Footnote
Serious delinquency: days past due	60 days	60 days
Multifamily | Maximum
Table Footnote
Serious delinquency: days past due	89 days	89 days
Multifamily | Total Delinquent
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option	$ 2,148	$ 1,128
Multifamily | 30-59 Days Delinquent
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option	449	173
Multifamily | Seriously Delinquent
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option	1,699	955
Multifamily | Current
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option	$ 459,206	$ 431,094