Mortgage Loans - Loan Restructuring - Summary of Loans Restructured (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2022
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	$ 27,527	$ 46,491
Restructured loans, percent of total financing receivable	1.00%	1.00%
Restructured loans, paid off during period	$ 269	$ 1,700
Forbearance Plan
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	12,099	15,803
Payment Deferral
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	5,638	12,552
Trial Modification and Repayment Plans
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	4,141	6,602
Payment Delay and Term Extension
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	815	1,971
Payment Delay, Term Extension and Interest Rate Reduction
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	4,834	9,563
Single-family
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	$ 27,493	$ 46,243
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	$ 12,076	$ 15,566
Single-family | Payment Deferral
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	5,638	12,552
Single-family | Trial Modification and Repayment Plans
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	4,141	6,602
Single-family | Payment Delay and Term Extension
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	815	1,971
Single-family | Payment Delay, Term Extension and Interest Rate Reduction
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	4,823	9,552
Single-family | 20- and 30-year or more, amortizing fixed-rate
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	$ 25,671	$ 43,006
Restructured loans, percent of total financing receivable	1.00%	1.00%
Single-family | 20- and 30-year or more, amortizing fixed-rate | Forbearance Plan
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	$ 11,213	$ 14,428
Single-family | 20- and 30-year or more, amortizing fixed-rate | Payment Deferral
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	5,203	11,518
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	3,815	6,064
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	769	1,831
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	4,671	9,165
Single-family | 15-year or less, amortizing fixed-rate
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	1,012	1,643
Single-family | 15-year or less, amortizing fixed-rate | Forbearance Plan
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	571	735
Single-family | 15-year or less, amortizing fixed-rate | Payment Deferral
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	287	653
Single-family | 15-year or less, amortizing fixed-rate | Trial Modification and Repayment Plans
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	154	253
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	1
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	0	1
Single-family | Adjustable-rate
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	120	$ 226
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	61	$ 84
Single-family | Adjustable-rate | Payment Deferral
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	27	77
Single-family | Adjustable-rate | Trial Modification and Repayment Plans
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	28	53
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	4	12
Single-family | Other
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	$ 690	$ 1,368
Restructured loans, percent of total financing receivable	2.00%	4.00%
Single-family | Other | Forbearance Plan
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	$ 231	$ 319
Single-family | Other | Payment Deferral
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	121	304
Single-family | Other | Trial Modification and Repayment Plans
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	144	232
Single-family | Other | Payment Delay and Term Extension
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	46	139
Single-family | Other | Payment Delay, Term Extension and Interest Rate Reduction
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	148	374
Multifamily
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	34	248
Multifamily | Forbearance Plan
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	23	237
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	$ 11	$ 11