Mortgage Loans - Loan Restructuring - Subsequent Default (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	$ 2,304	$ 2,078	$ 3,753	$ 3,427
Payment Delay as a Result of a Payment Deferral (Only)
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	1,198	1,236	1,946	2,078
Payment Delay and Term Extension
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	1,005	813	1,640	1,303
Payment Delay, Term Extension, Interest Rate Reduction, and Other
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	101	29	167	46
Single-family
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	2,304	2,078	3,753	3,427
Single-family \| Payment Delay as a Result of a Payment Deferral (Only)
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	1,198	1,236	1,946	2,078
Single-family \| Payment Delay and Term Extension
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	1,005	813	1,640	1,303
Single-family \| Payment Delay, Term Extension, Interest Rate Reduction, and Other
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	101	29	167	46
Single-family \| 20- and 30-year or more, amortizing fixed-rate
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	2,237	2,023	3,642	3,331
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	1,156	1,190	1,873	1,998
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	982	807	1,607	1,293
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	99	26	162	40
Single-family \| 15-year or less, amortizing fixed-rate
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	44	31	72	55
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	28	31	50	55
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	16	0	21	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	1	0
Single-family \| Adjustable-rate
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	3	4	4	8
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	4	6
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	0	1	0	2
Single-family \| Other
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	20	20	35	33
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	11	12	19	19
Single-family \| Other \| Payment Delay and Term Extension
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	7	6	12	10
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	2	4	4
Multifamily
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	0	0	0	0
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	$ 0	$ 0	$ 0