Mortgage Loans - Loan Restructuring - Aging Analysis (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023	Dec. 31, 2023
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	$ 15,345	$ 17,934	$ 25,326	$ 28,452
Serious delinquency, days past due			90 days
Forbearance and Repayment Plans and Trial Modification
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost			$ 32,626	39,319
30 - 59 Days Delinquent | Forbearance and Repayment Plans and Trial Modification
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost			4,157	3,652
60 - 89 Days Delinquent | Forbearance and Repayment Plans and Trial Modification
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost			2,468	2,361
Seriously Delinquent | Forbearance and Repayment Plans and Trial Modification
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost			11,559	13,172
Total Delinquent | Forbearance and Repayment Plans and Trial Modification
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost			18,184	19,185
Current | Forbearance and Repayment Plans and Trial Modification
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost			14,442	20,134
Single-family
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	15,259	16,986	$ 25,233	27,134
Single-family | Minimum
Loans in Mortgage Portfolio [Line Items]
Serious delinquency, days past due			90 days		90 days
Single-family | Forbearance and Repayment Plans and Trial Modification
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost			$ 31,382	37,970
Single-family | 30 - 59 Days Delinquent | Forbearance and Repayment Plans and Trial Modification
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost			4,157	3,652
Single-family | 60 - 89 Days Delinquent | Forbearance and Repayment Plans and Trial Modification
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost			2,468	2,361
Single-family | Seriously Delinquent | Forbearance and Repayment Plans and Trial Modification
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost			11,198	12,792
Single-family | Total Delinquent | Forbearance and Repayment Plans and Trial Modification
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost			17,823	18,805
Single-family | Current | Forbearance and Repayment Plans and Trial Modification
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost			13,559	19,165
Single-family | 20- and 30-year or more, amortizing fixed-rate
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	14,606	16,066	24,146	25,644
Single-family | 20- and 30-year or more, amortizing fixed-rate | Forbearance and Repayment Plans and Trial Modification
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost			29,943	35,764
Single-family | 20- and 30-year or more, amortizing fixed-rate | 30 - 59 Days Delinquent | Forbearance and Repayment Plans and Trial Modification
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost			3,970	3,442
Single-family | 20- and 30-year or more, amortizing fixed-rate | 60 - 89 Days Delinquent | Forbearance and Repayment Plans and Trial Modification
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost			2,359	2,227
Single-family | 20- and 30-year or more, amortizing fixed-rate | Seriously Delinquent | Forbearance and Repayment Plans and Trial Modification
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost			10,681	12,035
Single-family | 20- and 30-year or more, amortizing fixed-rate | Total Delinquent | Forbearance and Repayment Plans and Trial Modification
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost			17,010	17,704
Single-family | 20- and 30-year or more, amortizing fixed-rate | Current | Forbearance and Repayment Plans and Trial Modification
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost			12,933	18,060
Single-family | 15-year or less, amortizing fixed-rate
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	442	588	708	919
Single-family | 15-year or less, amortizing fixed-rate | Forbearance and Repayment Plans and Trial Modification
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost			930	1,282
Single-family | 15-year or less, amortizing fixed-rate | 30 - 59 Days Delinquent | Forbearance and Repayment Plans and Trial Modification
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost			116	114
Single-family | 15-year or less, amortizing fixed-rate | 60 - 89 Days Delinquent | Forbearance and Repayment Plans and Trial Modification
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost			63	82
Single-family | 15-year or less, amortizing fixed-rate | Seriously Delinquent | Forbearance and Repayment Plans and Trial Modification
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost			348	447
Single-family | 15-year or less, amortizing fixed-rate | Total Delinquent | Forbearance and Repayment Plans and Trial Modification
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost			527	643
Single-family | 15-year or less, amortizing fixed-rate | Current | Forbearance and Repayment Plans and Trial Modification
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost			403	639
Single-family | Adjustable-rate
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	52	69	89	102
Single-family | Adjustable-rate | Forbearance and Repayment Plans and Trial Modification
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost			109	148
Single-family | Adjustable-rate | 30 - 59 Days Delinquent | Forbearance and Repayment Plans and Trial Modification
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost			11	14
Single-family | Adjustable-rate | 60 - 89 Days Delinquent | Forbearance and Repayment Plans and Trial Modification
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost			10	9
Single-family | Adjustable-rate | Seriously Delinquent | Forbearance and Repayment Plans and Trial Modification
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost			45	59
Single-family | Adjustable-rate | Total Delinquent | Forbearance and Repayment Plans and Trial Modification
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost			66	82
Single-family | Adjustable-rate | Current | Forbearance and Repayment Plans and Trial Modification
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost			43	66
Single-family | Other
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	159	263	290	469
Single-family | Other | Forbearance and Repayment Plans and Trial Modification
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost			400	776
Single-family | Other | 30 - 59 Days Delinquent | Forbearance and Repayment Plans and Trial Modification
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost			60	82
Single-family | Other | 60 - 89 Days Delinquent | Forbearance and Repayment Plans and Trial Modification
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost			36	43
Single-family | Other | Seriously Delinquent | Forbearance and Repayment Plans and Trial Modification
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost			124	251
Single-family | Other | Total Delinquent | Forbearance and Repayment Plans and Trial Modification
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost			220	376
Single-family | Other | Current | Forbearance and Repayment Plans and Trial Modification
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost			180	400
Multifamily
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost	$ 86	$ 948	$ 93	1,318
Multifamily | Minimum
Loans in Mortgage Portfolio [Line Items]
Serious delinquency, days past due			60 days
Multifamily | Maximum
Loans in Mortgage Portfolio [Line Items]
Serious delinquency, days past due			89 days
Multifamily | Forbearance and Repayment Plans and Trial Modification
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost			$ 1,244	1,349
Multifamily | 30 - 59 Days Delinquent | Forbearance and Repayment Plans and Trial Modification
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost			0	0
Multifamily | Seriously Delinquent | Forbearance and Repayment Plans and Trial Modification
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost			361	380
Multifamily | Total Delinquent | Forbearance and Repayment Plans and Trial Modification
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost			361	380
Multifamily | Current | Forbearance and Repayment Plans and Trial Modification
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost			$ 883	$ 969