Mortgage Loans - Loan Restructuring - Subsequent Default (Details) $ in Millions	3 Months Ended
	Mar. 31, 2023 USD ($)
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	$ 1,313
Payment Deferral
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	810
Payment Delay and Term Extension
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	204
Payment Delay, Term Extension and Interest Rate Reduction
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	299
Single-family
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	1,313
Single-family | Payment Deferral
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	810
Single-family | Payment Delay and Term Extension
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	204
Single-family | Payment Delay, Term Extension and Interest Rate Reduction
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	299
Single-family | 20- and 30-year or more, amortizing fixed-rate
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	1,250
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
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	200
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	284
Single-family | 15-year or less, amortizing fixed-rate
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	27
Single-family | 15-year or less, amortizing fixed-rate | Payment Deferral
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	27
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
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
Single-family | Adjustable-rate
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	4
Single-family | Adjustable-rate | Payment Deferral
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	3
Single-family | Adjustable-rate | Payment Delay and Term Extension
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	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	1
Single-family | Other
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	32
Single-family | Other | Payment Deferral
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	14
Single-family | Other | Payment Delay and Term Extension
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	4
Single-family | Other | Payment Delay, Term Extension and Interest Rate Reduction
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	14
Multifamily
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	0
Multifamily | Payment Deferral
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	0
Multifamily | Payment Delay and Term Extension
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	0
Multifamily | Payment Delay, Term Extension and Interest Rate Reduction
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	$ 0