Mortgage Loans - Loan Restructuring - Summary of Loans Restructured (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	$ 21,342	$ 51,704
Restructured loans, percent of total financing receivable	1.00%	1.00%
Restructured loans, paid off, repurchased or sold during period	$ 205	$ 3,000
Forbearance Plan
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	10,517	15,154
Payment Deferral
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	4,122	15,935
Trial Modification and Repayment Plans
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	3,099	5,883
Payment Delay and Term Extension
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	1,170	2,943
Payment Delay, Term Extension and Interest Rate Reduction
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	2,434	11,789
Single-family
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	$ 21,318	$ 51,499
Restructured loans, percent of total financing receivable	1.00%	1.00%
Single-family | Forbearance Plan
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	$ 10,511	$ 14,967
Single-family | Payment Deferral
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	4,122	15,935
Single-family | Trial Modification and Repayment Plans
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	3,099	5,883
Single-family | Payment Delay and Term Extension
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	1,170	2,943
Single-family | Payment Delay, Term Extension and Interest Rate Reduction
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	2,416	11,771
Single-family | 20- and 30-year or more, amortizing fixed-rate
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	$ 19,972	$ 48,106
Restructured loans, percent of total financing receivable	1.00%	2.00%
Single-family | 20- and 30-year or more, amortizing fixed-rate | Forbearance Plan
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	$ 9,811	$ 13,905
Single-family | 20- and 30-year or more, amortizing fixed-rate | Payment Deferral
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	3,827	14,705
Single-family | 20- and 30-year or more, amortizing fixed-rate | Trial Modification and Repayment Plans
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	2,869	5,417
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	1,144	2,832
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	2,321	11,247
Single-family | 15-year or less, amortizing fixed-rate
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	805	1,739
Single-family | 15-year or less, amortizing fixed-rate | Forbearance Plan
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	478	697
Single-family | 15-year or less, amortizing fixed-rate | Payment Deferral
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	196	794
Single-family | 15-year or less, amortizing fixed-rate | Trial Modification and Repayment Plans
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	129	245
Single-family | 15-year or less, amortizing fixed-rate | Payment Delay and Term Extension
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	1	2
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	1
Single-family | Adjustable-rate
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	89	$ 224
Restructured loans, percent of total financing receivable		1.00%
Single-family | Adjustable-rate | Forbearance Plan
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	49	$ 76
Single-family | Adjustable-rate | Payment Deferral
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	22	83
Single-family | Adjustable-rate | Trial Modification and Repayment Plans
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	15	39
Single-family | Adjustable-rate | Payment Delay and Term Extension
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	0	0
Single-family | Adjustable-rate | Payment Delay, Term Extension and Interest Rate Reduction
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	3	26
Single-family | Other
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	$ 452	$ 1,430
Restructured loans, percent of total financing receivable	1.00%	4.00%
Single-family | Other | Forbearance Plan
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	$ 173	$ 289
Single-family | Other | Payment Deferral
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	77	353
Single-family | Other | Trial Modification and Repayment Plans
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	86	182
Single-family | Other | Payment Delay and Term Extension
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	25	109
Single-family | Other | Payment Delay, Term Extension and Interest Rate Reduction
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	91	497
Multifamily
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	24	205
Multifamily | Forbearance Plan
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	6	187
Multifamily | Payment Deferral
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	0	0
Multifamily | Trial Modification and Repayment Plans
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	0	0
Multifamily | Payment Delay and Term Extension
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	0	0
Multifamily | Payment Delay, Term Extension and Interest Rate Reduction
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	$ 18	$ 18