Mortgage Loans - Loan Restructuring - Aging Analysis (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	$ 39,289	$ 57,198
Forbearance and Repayment Plans and Trial Modification
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	34,663	51,895
30-59 Days Delinquent | Forbearance and Repayment Plans and Trial Modification
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	3,703	4,391
60 - 89 Days Delinquent | Forbearance and Repayment Plans and Trial Modification
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	2,447	2,980
Seriously Delinquent | Forbearance and Repayment Plans and Trial Modification
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	13,142	15,256
Total Delinquent | Forbearance and Repayment Plans and Trial Modification
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	19,292	22,627
Current | Forbearance and Repayment Plans and Trial Modification
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	15,371	29,268
Single-family
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	37,735	56,875
Single-family | Forbearance and Repayment Plans and Trial Modification
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	33,108	51,572
Single-family | 30-59 Days Delinquent | Forbearance and Repayment Plans and Trial Modification
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	3,703	4,388
Single-family | 60 - 89 Days Delinquent | Forbearance and Repayment Plans and Trial Modification
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	2,447	2,980
Single-family | Seriously Delinquent | Forbearance and Repayment Plans and Trial Modification
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	12,585	14,991
Single-family | Total Delinquent | Forbearance and Repayment Plans and Trial Modification
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	18,735	22,359
Single-family | Current | Forbearance and Repayment Plans and Trial Modification
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	14,373	29,213
Single-family | 20- and 30-year or more, amortizing fixed-rate
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	35,842	53,310
Single-family | 20- and 30-year or more, amortizing fixed-rate | Forbearance and Repayment Plans and Trial Modification
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	31,396	48,272
Single-family | 20- and 30-year or more, amortizing fixed-rate | 30-59 Days Delinquent | Forbearance and Repayment Plans and Trial Modification
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	3,520	4,113
Single-family | 20- and 30-year or more, amortizing fixed-rate | 60 - 89 Days Delinquent | Forbearance and Repayment Plans and Trial Modification
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	2,323	2,785
Single-family | 20- and 30-year or more, amortizing fixed-rate | Seriously Delinquent | Forbearance and Repayment Plans and Trial Modification
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	11,955	13,995
Single-family | 20- and 30-year or more, amortizing fixed-rate | Total Delinquent | Forbearance and Repayment Plans and Trial Modification
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	17,798	20,893
Single-family | 20- and 30-year or more, amortizing fixed-rate | Current | Forbearance and Repayment Plans and Trial Modification
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	13,598	27,379
Single-family | 15-year or less, amortizing fixed-rate
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	1,169	1,907
Single-family | 15-year or less, amortizing fixed-rate | Forbearance and Repayment Plans and Trial Modification
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	1,069	1,775
Single-family | 15-year or less, amortizing fixed-rate | 30-59 Days Delinquent | Forbearance and Repayment Plans and Trial Modification
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	111	147
Single-family | 15-year or less, amortizing fixed-rate | 60 - 89 Days Delinquent | Forbearance and Repayment Plans and Trial Modification
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	76	114
Single-family | 15-year or less, amortizing fixed-rate | Seriously Delinquent | Forbearance and Repayment Plans and Trial Modification
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	409	552
Single-family | 15-year or less, amortizing fixed-rate | Total Delinquent | Forbearance and Repayment Plans and Trial Modification
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	596	813
Single-family | 15-year or less, amortizing fixed-rate | Current | Forbearance and Repayment Plans and Trial Modification
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	473	962
Single-family | Adjustable-rate
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	137	241
Single-family | Adjustable-rate | Forbearance and Repayment Plans and Trial Modification
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	126	225
Single-family | Adjustable-rate | 30-59 Days Delinquent | Forbearance and Repayment Plans and Trial Modification
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	11	15
Single-family | Adjustable-rate | 60 - 89 Days Delinquent | Forbearance and Repayment Plans and Trial Modification
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	9	14
Single-family | Adjustable-rate | Seriously Delinquent | Forbearance and Repayment Plans and Trial Modification
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	56	79
Single-family | Adjustable-rate | Total Delinquent | Forbearance and Repayment Plans and Trial Modification
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	76	108
Single-family | Adjustable-rate | Current | Forbearance and Repayment Plans and Trial Modification
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	50	117
Single-family | Other
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	587	1,417
Single-family | Other | Forbearance and Repayment Plans and Trial Modification
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	517	1,300
Single-family | Other | 30-59 Days Delinquent | Forbearance and Repayment Plans and Trial Modification
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	61	113
Single-family | Other | 60 - 89 Days Delinquent | Forbearance and Repayment Plans and Trial Modification
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	39	67
Single-family | Other | Seriously Delinquent | Forbearance and Repayment Plans and Trial Modification
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	165	365
Single-family | Other | Total Delinquent | Forbearance and Repayment Plans and Trial Modification
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	265	545
Single-family | Other | Current | Forbearance and Repayment Plans and Trial Modification
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	252	755
Multifamily
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	1,554	323
Multifamily | Forbearance and Repayment Plans and Trial Modification
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	1,555	323
Multifamily | 30-59 Days Delinquent | Forbearance and Repayment Plans and Trial Modification
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	0	3
Multifamily | Seriously Delinquent | Forbearance and Repayment Plans and Trial Modification
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	557	265
Multifamily | Total Delinquent | Forbearance and Repayment Plans and Trial Modification
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	557	268
Multifamily | Current | Forbearance and Repayment Plans and Trial Modification
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	$ 998	$ 55