Mortgage Loans - Loan Restructuring - Subsequent Default (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2022	Sep. 30, 2022
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	$ 1,212	$ 1,671
Payment Deferral
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	815	1,156
Payment Delay and Term Extension
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	101	143
Payment Delay, Term Extension and Interest Rate Reduction
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	296	372
Single-family
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	1,212	1,671
Single-family | Payment Deferral
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	815	1,156
Single-family | Payment Delay and Term Extension
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	101	143
Single-family | Payment Delay, Term Extension and Interest Rate Reduction
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	296	372
Single-family | 20- and 30-year or more, amortizing fixed-rate
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	1,139	1,562
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	766	1,083
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	97	136
Single-family | 20- and 30-year or more, amortizing fixed-rate | Payment Delay, Term Extension and Interest Rate Reduction
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	276	343
Single-family | 15-year or less, amortizing fixed-rate
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	26	39
Single-family | 15-year or less, amortizing fixed-rate | Payment Deferral
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	26	39
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
Single-family | 15-year or less, amortizing fixed-rate | Payment Delay, Term Extension and Interest Rate Reduction
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	0	0
Single-family | Adjustable-rate
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	6	8
Single-family | Adjustable-rate | Payment Deferral
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	4	5
Single-family | Adjustable-rate | Payment Delay and Term Extension
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	0	0
Single-family | Adjustable-rate | Payment Delay, Term Extension and Interest Rate Reduction
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	2	3
Single-family | Other
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	41	62
Single-family | Other | Payment Deferral
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	19	29
Single-family | Other | Payment Delay and Term Extension
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	4	7
Single-family | Other | Payment Delay, Term Extension and Interest Rate Reduction
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	18	26
Multifamily
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	0	0
Multifamily | Payment Deferral
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	0	0
Multifamily | Payment Delay and Term Extension
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	0	0
Multifamily | Payment Delay, Term Extension and Interest Rate Reduction
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	$ 0	$ 0