Mortgage Loans - Aging (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2022
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option	$ 4,127,134		$ 4,129,751
Loans 90 Days or More Delinquent and Accruing Interest	7,853		14,448
Nonaccrual Loans with No Allowance	$ 4,052		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	$ 51,742		60,877
30 - 59 Days Delinquent
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option	23,913		30,802
60 - 89 Days Delinquent
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option	6,360		7,305
Seriously Delinquent
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option	21,469		22,770
Current
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option	4,075,392		4,068,874
Single-family
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option	3,690,096		3,697,529
Loans 90 Days or More Delinquent and Accruing Interest	7,655		14,437
Nonaccrual Loans with No Allowance	$ 3,405		$ 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	$ 50,207		$ 59,749
Single-family | 30 - 59 Days Delinquent
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option	23,699		30,629
Single-family | 60 - 89 Days Delinquent
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option	6,360		7,305
Single-family | Seriously Delinquent
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option	20,148		21,815
Single-family | Current
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option	3,639,889		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	3,156,711		3,146,854
Loans 90 Days or More Delinquent and Accruing Interest	6,929		13,257
Nonaccrual Loans with No Allowance	3,000		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	46,132		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	21,710		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	5,910		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	18,512		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	3,110,579		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	475,553		491,468
Loans 90 Days or More Delinquent and Accruing Interest	366		666
Nonaccrual Loans with No Allowance	96		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	2,296		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	1,308		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	266		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	722		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	473,257		488,452
Single-family | Adjustable-rate
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option	27,424		27,108
Loans 90 Days or More Delinquent and Accruing Interest	50		90
Nonaccrual Loans with No Allowance	22		24
Single-family | Adjustable-rate | Total Delinquent
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option	286		341
Single-family | Adjustable-rate | 30 - 59 Days Delinquent
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option	143		176
Single-family | Adjustable-rate | 60 - 89 Days Delinquent
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option	30		38
Single-family | Adjustable-rate | Seriously Delinquent
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option	113		127
Single-family | Adjustable-rate | Current
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option	27,138		26,767
Single-family | Other
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option	30,408		32,099
Loans 90 Days or More Delinquent and Accruing Interest	310		424
Nonaccrual Loans with No Allowance	287		324
Single-family | Other | Total Delinquent
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option	1,493		1,737
Single-family | Other | 30 - 59 Days Delinquent
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option	538		660
Single-family | Other | 60 - 89 Days Delinquent
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option	154		179
Single-family | Other | Seriously Delinquent
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option	801		898
Single-family | Other | Current
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option	28,915		30,362
Multifamily
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option	437,038		432,222
Loans 90 Days or More Delinquent and Accruing Interest	198		11
Nonaccrual Loans with No Allowance	$ 647		13
Multifamily | Minimum
Table Footnote [Abstract]
Serious delinquency, days past due	60 days	60 days
Multifamily | Total Delinquent
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option	$ 1,535		1,128
Multifamily | 30 - 59 Days Delinquent
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option	214		173
Multifamily | Seriously Delinquent
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option	1,321		955
Multifamily | Current
Financing Receivable, Past Due [Line Items]
Loans held for investment, excluding fair value option	$ 435,503		$ 431,094