Mortgage Loans - Loan Restructuring - Subsequent Default (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	$ 2,078	$ 1,889	$ 3,427	$ 2,788
Payment Delay as a Result of a Payment Deferral (Only)
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	1,236	1,228	2,078	1,806
Payment Delay and Term Extension
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	813	633	1,303	936
Payment Delay, Term Extension, Interest Rate Reduction, and Other
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	29	28	46	46
Single-family
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	2,078	1,876	3,427	2,770
Single-family | Payment Delay as a Result of a Payment Deferral (Only)
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	1,236	1,228	2,078	1,806
Single-family | Payment Delay and Term Extension
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	813	633	1,303	936
Single-family | Payment Delay, Term Extension, Interest Rate Reduction, and Other
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	29	15	46	28
Single-family | 20- and 30-year or more, amortizing fixed-rate
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	2,023	1,812	3,331	2,670
Single-family | 20- and 30-year or more, amortizing fixed-rate | Payment Delay as a Result of a Payment Deferral (Only)
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	1,190	1,178	1,998	1,727
Single-family | 20- and 30-year or more, amortizing fixed-rate | Payment Delay and Term Extension
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	807	625	1,293	925
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, amortized cost, subsequent default	26	9	40	18
Single-family | 15-year or less, amortizing fixed-rate
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	31	31	55	51
Single-family | 15-year or less, amortizing fixed-rate | Payment Delay as a Result of a Payment Deferral (Only)
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	31	31	55	51
Single-family | 15-year or less, amortizing fixed-rate | Payment Delay and Term Extension
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	0	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, amortized cost, subsequent default	0	0	0	0
Single-family | Adjustable-rate
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	4	4	8	7
Single-family | Adjustable-rate | Payment Delay as a Result of a Payment Deferral (Only)
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	3	3	6	5
Single-family | Adjustable-rate | Payment Delay and Term Extension
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	0	0	0	0
Single-family | Adjustable-rate | Payment Delay, Term Extension, Interest Rate Reduction, and Other
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	1	1	2	2
Single-family | Other
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	20	29	33	42
Single-family | Other | Payment Delay as a Result of a Payment Deferral (Only)
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	12	16	19	23
Single-family | Other | Payment Delay and Term Extension
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	6	8	10	11
Single-family | Other | Payment Delay, Term Extension, Interest Rate Reduction, and Other
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	2	5	4	8
Multifamily
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	0	13	0	18
Multifamily | Payment Delay as a Result of a Payment Deferral (Only)
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	0	0	0	0
Multifamily | Payment Delay and Term Extension
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	0	0	0	0
Multifamily | Payment Delay, Term Extension, Interest Rate Reduction, and Other
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	$ 0	$ 13	$ 0	$ 18