Mortgage Loans - Loan Restructuring - Subsequent Default (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Loans in Mortgage Portfolio [Line Items]
Restructured loans, subsequent default	$ 5,188	$ 3,373	$ 2,761
Payment Deferral
Loans in Mortgage Portfolio [Line Items]
Restructured loans, subsequent default	3,337	2,018	1,799
Payment Delay and Term Extension
Loans in Mortgage Portfolio [Line Items]
Restructured loans, subsequent default	1,799	1,100	269
Payment Delay, Term Extension, Interest Rate Reduction, and Other
Loans in Mortgage Portfolio [Line Items]
Restructured loans, subsequent default	52	255	693
Single-family
Loans in Mortgage Portfolio [Line Items]
Restructured loans, subsequent default	5,188	3,373	2,761
Single-family | Payment Deferral
Loans in Mortgage Portfolio [Line Items]
Restructured loans, subsequent default	3,337	2,018	1,799
Single-family | Payment Delay and Term Extension
Loans in Mortgage Portfolio [Line Items]
Restructured loans, subsequent default	1,799	1,100	269
Single-family | Payment Delay, Term Extension, Interest Rate Reduction, and Other
Loans in Mortgage Portfolio [Line Items]
Restructured loans, subsequent default	52	255	693
Single-family | 20- and 30-year or more, amortizing fixed-rate
Loans in Mortgage Portfolio [Line Items]
Restructured loans, subsequent default	5,030	3,244	2,601
Single-family | 20- and 30-year or more, amortizing fixed-rate | Payment Deferral
Loans in Mortgage Portfolio [Line Items]
Restructured loans, subsequent default	3,209	1,933	1,695
Single-family | 20- and 30-year or more, amortizing fixed-rate | Payment Delay and Term Extension
Loans in Mortgage Portfolio [Line Items]
Restructured loans, subsequent default	1,786	1,078	258
Single-family | 20- and 30-year or more, amortizing fixed-rate | Payment Delay, Term Extension, Interest Rate Reduction, and Other
Loans in Mortgage Portfolio [Line Items]
Restructured loans, subsequent default	35	233	648
Single-family | 15-year or less, amortizing fixed-rate
Loans in Mortgage Portfolio [Line Items]
Restructured loans, subsequent default	79	58	56
Single-family | 15-year or less, amortizing fixed-rate | Payment Deferral
Loans in Mortgage Portfolio [Line Items]
Restructured loans, subsequent default	79	57	56
Single-family | 15-year or less, amortizing fixed-rate | Payment Delay and Term Extension
Loans in Mortgage Portfolio [Line Items]
Restructured loans, subsequent default	0	0	0
Single-family | 15-year or less, amortizing fixed-rate | Payment Delay, Term Extension, Interest Rate Reduction, and Other
Loans in Mortgage Portfolio [Line Items]
Restructured loans, subsequent default	0	1	0
Single-family | Adjustable-rate
Loans in Mortgage Portfolio [Line Items]
Restructured loans, subsequent default	15	7	10
Single-family | Adjustable-rate | Payment Deferral
Loans in Mortgage Portfolio [Line Items]
Restructured loans, subsequent default	12	5	7
Single-family | Adjustable-rate | Payment Delay and Term Extension
Loans in Mortgage Portfolio [Line Items]
Restructured loans, subsequent default	0	0	0
Single-family | Adjustable-rate | Payment Delay, Term Extension, Interest Rate Reduction, and Other
Loans in Mortgage Portfolio [Line Items]
Restructured loans, subsequent default	3	2	3
Single-family | Other
Loans in Mortgage Portfolio [Line Items]
Restructured loans, subsequent default	64	64	94
Single-family | Other | Payment Deferral
Loans in Mortgage Portfolio [Line Items]
Restructured loans, subsequent default	37	23	41
Single-family | Other | Payment Delay and Term Extension
Loans in Mortgage Portfolio [Line Items]
Restructured loans, subsequent default	13	22	11
Single-family | Other | Payment Delay, Term Extension, Interest Rate Reduction, and Other
Loans in Mortgage Portfolio [Line Items]
Restructured loans, subsequent default	14	19	42
Multifamily
Loans in Mortgage Portfolio [Line Items]
Restructured loans, subsequent default	0	0	0
Multifamily | Payment Deferral
Loans in Mortgage Portfolio [Line Items]
Restructured loans, subsequent default	0	0	0
Multifamily | Payment Delay and Term Extension
Loans in Mortgage Portfolio [Line Items]
Restructured loans, subsequent default	0	0	0
Multifamily | Payment Delay, Term Extension, Interest Rate Reduction, and Other
Loans in Mortgage Portfolio [Line Items]
Restructured loans, subsequent default	$ 0	$ 0	$ 0