Mortgage Loans - Loan Restructuring - Subsequent Default (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	$ 2,299	$ 1,466	$ 4,146	$ 2,788
Payment Deferral
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	1,499	902	2,705	1,710
Payment Delay and Term Extension
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	783	477	1,398	761
Payment Delay, Term Extension, Interest Rate Reduction and Other
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	17	87	43	317
Single-family
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	2,299	1,466	4,142	2,788
Single-family | Payment Deferral
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	1,499	902	2,705	1,710
Single-family | Payment Delay and Term Extension
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	783	477	1,398	761
Single-family | Payment Delay, Term Extension, Interest Rate Reduction and Other
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	17	87	39	317
Single-family | 20- and 30-year or more, amortizing fixed-rate
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	2,223	1,409	4,000	2,679
Single-family | 20- and 30-year or more, amortizing fixed-rate | Payment Deferral
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	1,438	861	2,592	1,635
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	774	468	1,383	746
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	11	80	25	298
Single-family | 15-year or less, amortizing fixed-rate
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	40	28	73	52
Single-family | 15-year or less, amortizing fixed-rate | Payment Deferral
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	40	28	73	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	1
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	2	9	6
Single-family | Adjustable-rate | Payment Deferral
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	4	1	7	4
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	2	2
Single-family | Other
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	32	27	60	51
Single-family | Other | Payment Deferral
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	17	12	33	20
Single-family | Other | Payment Delay and Term Extension
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	9	9	15	14
Single-family | Other | Payment Delay, Term Extension, Interest Rate Reduction and Other
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	6	6	12	17
Multifamily
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	0	0	4	0
Multifamily | Payment Deferral
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	$ 4	$ 0