Mortgage Loans - Loan Restructuring - Summary of Loans Restructured (Details) $ in Millions	3 Months Ended
	Mar. 31, 2022 USD ($)
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	$ 37,039
Restructured loans, percent of total financing receivable	1.00%
Forbearance and Repayment Plans
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	$ 17,737
Trial Modification
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	5,866
Payment Deferral
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	7,432
Payment Delay and Term Extension
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	1,225
Payment Delay, Term Extension and Interest Rate Reduction
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	4,779
Single-family
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	$ 36,743
Restructured loans, percent of total financing receivable	1.00%
Single-family | Forbearance and Repayment Plans
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	$ 17,470
Single-family | Trial Modification
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	5,866
Single-family | Payment Deferral
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	7,432
Single-family | Payment Delay and Term Extension
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	1,196
Single-family | Payment Delay, Term Extension and Interest Rate Reduction
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	4,779
Single-family | 20- and 30-year or more, amortizing fixed-rate
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	$ 33,954
Restructured loans, percent of total financing receivable	1.00%
Single-family | 20- and 30-year or more, amortizing fixed-rate | Forbearance and Repayment Plans
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	$ 16,140
Single-family | 20- and 30-year or more, amortizing fixed-rate | Trial Modification
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	5,380
Single-family | 20- and 30-year or more, amortizing fixed-rate | Payment Deferral
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	6,784
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	1,103
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	4,547
Single-family | 15-year or less, amortizing fixed-rate
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	1,437
Single-family | 15-year or less, amortizing fixed-rate | Forbearance and Repayment Plans
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	831
Single-family | 15-year or less, amortizing fixed-rate | Trial Modification
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	211
Single-family | 15-year or less, amortizing fixed-rate | Payment Deferral
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	394
Single-family | 15-year or less, amortizing fixed-rate | Payment Delay and Term Extension
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	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	1
Single-family | Adjustable-rate
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	$ 213
Restructured loans, percent of total financing receivable	1.00%
Single-family | Adjustable-rate | Forbearance and Repayment Plans
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	$ 100
Single-family | Adjustable-rate | Trial Modification
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	51
Single-family | Adjustable-rate | Payment Deferral
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	57
Single-family | Adjustable-rate | Payment Delay and Term Extension
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	0
Single-family | Adjustable-rate | Payment Delay, Term Extension and Interest Rate Reduction
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	5
Single-family | Other
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	$ 1,139
Restructured loans, percent of total financing receivable	3.00%
Single-family | Other | Forbearance and Repayment Plans
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	$ 399
Single-family | Other | Trial Modification
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	224
Single-family | Other | Payment Deferral
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	197
Single-family | Other | Payment Delay and Term Extension
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	93
Single-family | Other | Payment Delay, Term Extension and Interest Rate Reduction
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	226
Multifamily
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	296
Multifamily | Forbearance and Repayment Plans
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	267
Multifamily | Trial Modification
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	0
Multifamily | Payment Deferral
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	0
Multifamily | Payment Delay and Term Extension
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	29
Multifamily | Payment Delay, Term Extension and Interest Rate Reduction
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	$ 0