Mortgage Loans - Aging (Details) - USD ($) $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2023	Dec. 31, 2022
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option	$ 4,136,900	$ 4,129,751
Loans 90 Days or More Delinquent and Accruing Interest	4,791	14,448
Nonaccrual Loans with No Allowance	$ 4,390	3,697
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	$ 55,397	60,877
30 - 59 Days Delinquent
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option	28,013	30,802
60 - 89 Days Delinquent
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option	6,843	7,305
Seriously Delinquent
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option	20,541	22,770
Current
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option	4,081,503	4,068,874
Single-family
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option	3,690,750	3,697,529
Loans 90 Days or More Delinquent and Accruing Interest	4,450	14,437
Nonaccrual Loans with No Allowance	$ 3,662	$ 3,684
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	$ 53,439	$ 59,749
Single-family | 30 - 59 Days Delinquent
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option	27,432	30,629
Single-family | 60 - 89 Days Delinquent
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option	6,843	7,305
Single-family | Seriously Delinquent
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option	19,164	21,815
Single-family | Current
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option	3,637,311	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	3,175,715	3,146,854
Loans 90 Days or More Delinquent and Accruing Interest	3,962	13,257
Nonaccrual Loans with No Allowance	3,236	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	49,330	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	25,262	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	6,392	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	17,676	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	3,126,385	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	459,493	491,468
Loans 90 Days or More Delinquent and Accruing Interest	212	666
Nonaccrual Loans with No Allowance	137	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	2,414	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	1,475	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	272	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	667	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	457,079	488,452
Single-family | Adjustable-rate
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option	27,310	27,108
Loans 90 Days or More Delinquent and Accruing Interest	33	90
Nonaccrual Loans with No Allowance	25	24
Single-family | Adjustable-rate | Total Delinquent
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option	282	341
Single-family | Adjustable-rate | 30 - 59 Days Delinquent
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option	144	176
Single-family | Adjustable-rate | 60 - 89 Days Delinquent
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option	33	38
Single-family | Adjustable-rate | Seriously Delinquent
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option	105	127
Single-family | Adjustable-rate | Current
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option	27,028	26,767
Single-family | Other
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option	28,232	32,099
Loans 90 Days or More Delinquent and Accruing Interest	243	424
Nonaccrual Loans with No Allowance	264	324
Single-family | Other | Total Delinquent
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option	1,413	1,737
Single-family | Other | 30 - 59 Days Delinquent
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option	551	660
Single-family | Other | 60 - 89 Days Delinquent
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option	146	179
Single-family | Other | Seriously Delinquent
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option	716	898
Single-family | Other | Current
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option	26,819	30,362
Multifamily
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option	446,150	432,222
Loans 90 Days or More Delinquent and Accruing Interest	341	11
Nonaccrual Loans with No Allowance	$ 728	13
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	$ 1,958	1,128
Multifamily | 30 - 59 Days Delinquent
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option	581	173
Multifamily | Seriously Delinquent
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option	1,377	955
Multifamily | Current
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option	$ 444,192	$ 431,094