Mortgage Loans - Aging Analysis (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Financing Receivable, Past Due [Line Items]
Recorded investment	$ 3,973,024	$ 3,662,711
Loans 90 Days or More Delinquent and Accruing Interest	27,302	77,196
Nonaccrual Loans with No Allowance	7,179	7,455
30 - 59 Days Delinquent
Financing Receivable, Past Due [Line Items]
Recorded investment	25,947	29,473
60 - 89 Days Delinquent
Financing Receivable, Past Due [Line Items]
Recorded investment	5,758	10,570
Seriously Delinquent
Financing Receivable, Past Due [Line Items]
Recorded investment	44,096	103,172
Total Delinquent
Financing Receivable, Past Due [Line Items]
Recorded investment	75,801	143,215
Current
Financing Receivable, Past Due [Line Items]
Recorded investment	3,897,223	3,519,496
Single-family
Financing Receivable, Past Due [Line Items]
Recorded investment	3,566,819	3,285,285
Loans 90 Days or More Delinquent and Accruing Interest	26,985	76,586
Nonaccrual Loans with No Allowance	$ 7,072	$ 7,153
Single-family | Minimum
Table Footnote
Serious delinquency: days past due	90 days	90 days
Single-family | 30 - 59 Days Delinquent
Financing Receivable, Past Due [Line Items]
Recorded investment	$ 25,833	$ 28,333
Single-family | 60 - 89 Days Delinquent
Financing Receivable, Past Due [Line Items]
Recorded investment	5,758	10,570
Single-family | Seriously Delinquent
Financing Receivable, Past Due [Line Items]
Recorded investment	42,403	99,484
Single-family | Total Delinquent
Financing Receivable, Past Due [Line Items]
Recorded investment	73,994	138,387
Single-family | Current
Financing Receivable, Past Due [Line Items]
Recorded investment	3,492,825	3,146,898
Single-family | 20- and 30-year or more, amortizing fixed-rate
Financing Receivable, Past Due [Line Items]
Recorded investment	2,969,105	2,742,203
Loans 90 Days or More Delinquent and Accruing Interest	24,236	68,526
Nonaccrual Loans with No Allowance	6,271	6,028
Single-family | 20- and 30-year or more, amortizing fixed-rate | 30 - 59 Days Delinquent
Financing Receivable, Past Due [Line Items]
Recorded investment	22,862	24,928
Single-family | 20- and 30-year or more, amortizing fixed-rate | 60 - 89 Days Delinquent
Financing Receivable, Past Due [Line Items]
Recorded investment	5,192	9,414
Single-family | 20- and 30-year or more, amortizing fixed-rate | Seriously Delinquent
Financing Receivable, Past Due [Line Items]
Recorded investment	38,288	88,276
Single-family | 20- and 30-year or more, amortizing fixed-rate | Total Delinquent
Financing Receivable, Past Due [Line Items]
Recorded investment	66,342	122,618
Single-family | 20- and 30-year or more, amortizing fixed-rate | Current
Financing Receivable, Past Due [Line Items]
Recorded investment	2,902,763	2,619,585
Single-family | 15-year or less, amortizing fixed-rate
Financing Receivable, Past Due [Line Items]
Recorded investment	533,427	457,059
Loans 90 Days or More Delinquent and Accruing Interest	1,454	4,292
Nonaccrual Loans with No Allowance	193	240
Single-family | 15-year or less, amortizing fixed-rate | 30 - 59 Days Delinquent
Financing Receivable, Past Due [Line Items]
Recorded investment	2,024	1,987
Single-family | 15-year or less, amortizing fixed-rate | 60 - 89 Days Delinquent
Financing Receivable, Past Due [Line Items]
Recorded investment	326	601
Single-family | 15-year or less, amortizing fixed-rate | Seriously Delinquent
Financing Receivable, Past Due [Line Items]
Recorded investment	1,799	5,028
Single-family | 15-year or less, amortizing fixed-rate | Total Delinquent
Financing Receivable, Past Due [Line Items]
Recorded investment	4,149	7,616
Single-family | 15-year or less, amortizing fixed-rate | Current
Financing Receivable, Past Due [Line Items]
Recorded investment	529,278	449,443
Single-family | Adjustable-rate
Financing Receivable, Past Due [Line Items]
Recorded investment	26,342	31,441
Loans 90 Days or More Delinquent and Accruing Interest	287	907
Nonaccrual Loans with No Allowance	63	114
Single-family | Adjustable-rate | 30 - 59 Days Delinquent
Financing Receivable, Past Due [Line Items]
Recorded investment	161	268
Single-family | Adjustable-rate | 60 - 89 Days Delinquent
Financing Receivable, Past Due [Line Items]
Recorded investment	36	97
Single-family | Adjustable-rate | Seriously Delinquent
Financing Receivable, Past Due [Line Items]
Recorded investment	374	1,143
Single-family | Adjustable-rate | Total Delinquent
Financing Receivable, Past Due [Line Items]
Recorded investment	571	1,508
Single-family | Adjustable-rate | Current
Financing Receivable, Past Due [Line Items]
Recorded investment	25,771	29,933
Single-family | Other
Financing Receivable, Past Due [Line Items]
Recorded investment	37,945	54,582
Loans 90 Days or More Delinquent and Accruing Interest	1,008	2,861
Nonaccrual Loans with No Allowance	545	771
Single-family | Other | 30 - 59 Days Delinquent
Financing Receivable, Past Due [Line Items]
Recorded investment	786	1,150
Single-family | Other | 60 - 89 Days Delinquent
Financing Receivable, Past Due [Line Items]
Recorded investment	204	458
Single-family | Other | Seriously Delinquent
Financing Receivable, Past Due [Line Items]
Recorded investment	1,942	5,037
Single-family | Other | Total Delinquent
Financing Receivable, Past Due [Line Items]
Recorded investment	2,932	6,645
Single-family | Other | Current
Financing Receivable, Past Due [Line Items]
Recorded investment	35,013	47,937
Multifamily
Financing Receivable, Past Due [Line Items]
Recorded investment	406,205	377,426
Loans 90 Days or More Delinquent and Accruing Interest	317	610
Nonaccrual Loans with No Allowance	$ 107	302
Multifamily | Minimum
Table Footnote
Serious delinquency: days past due	60 days
Multifamily | Maximum
Table Footnote
Serious delinquency: days past due	89 days
Multifamily | 30 - 59 Days Delinquent
Financing Receivable, Past Due [Line Items]
Recorded investment	$ 114	1,140
Multifamily | Seriously Delinquent
Financing Receivable, Past Due [Line Items]
Recorded investment	1,693	3,688
Multifamily | Total Delinquent
Financing Receivable, Past Due [Line Items]
Recorded investment	1,807	4,828
Multifamily | Current
Financing Receivable, Past Due [Line Items]
Recorded investment	$ 404,398	$ 372,598