Mortgage Loans - Amortized Cost Basis of Single-Family Restructured Loans Involving Borrowers Experiencing Financial Difficulty by Payment Status (Details) - USD ($) $ in Millions	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Single Family
financing receivable, loan restructuring [Line Items]
Financing receivable, loan restructuring, amortized cost basis	$ 28,934	$ 25,159	$ 21,954
Single Family | Financial Asset, Not Past Due
financing receivable, loan restructuring [Line Items]
Financing receivable, loan restructuring, amortized cost basis	14,827	11,393	11,533
Single Family | One month past due
financing receivable, loan restructuring [Line Items]
Financing receivable, loan restructuring, amortized cost basis	4,184	3,638	2,730
Single Family | Two months past due
financing receivable, loan restructuring [Line Items]
Financing receivable, loan restructuring, amortized cost basis	2,709	2,790	1,599
Single Family | Three months or more past due or in foreclosure
financing receivable, loan restructuring [Line Items]
Financing receivable, loan restructuring, amortized cost basis	7,214	7,338	6,092
20- and 30-year or more, amortizing fixed-rate
financing receivable, loan restructuring [Line Items]
Financing receivable, loan restructuring, amortized cost basis	28,082	24,244	20,953
20- and 30-year or more, amortizing fixed-rate | Financial Asset, Not Past Due
financing receivable, loan restructuring [Line Items]
Financing receivable, loan restructuring, amortized cost basis	14,431	11,011	11,000
20- and 30-year or more, amortizing fixed-rate | One month past due
financing receivable, loan restructuring [Line Items]
Financing receivable, loan restructuring, amortized cost basis	4,056	3,501	2,619
20- and 30-year or more, amortizing fixed-rate | Two months past due
financing receivable, loan restructuring [Line Items]
Financing receivable, loan restructuring, amortized cost basis	2,621	2,685	1,525
20- and 30-year or more, amortizing fixed-rate | Three months or more past due or in foreclosure
financing receivable, loan restructuring [Line Items]
Financing receivable, loan restructuring, amortized cost basis	6,974	7,047	5,809
15-year or less, amortizing fixed-rate
financing receivable, loan restructuring [Line Items]
Financing receivable, loan restructuring, amortized cost basis	659	723	797
15-year or less, amortizing fixed-rate | Financial Asset, Not Past Due
financing receivable, loan restructuring [Line Items]
Financing receivable, loan restructuring, amortized cost basis	309	309	432
15-year or less, amortizing fixed-rate | One month past due
financing receivable, loan restructuring [Line Items]
Financing receivable, loan restructuring, amortized cost basis	104	112	88
15-year or less, amortizing fixed-rate | Two months past due
financing receivable, loan restructuring [Line Items]
Financing receivable, loan restructuring, amortized cost basis	72	86	57
15-year or less, amortizing fixed-rate | Three months or more past due or in foreclosure
financing receivable, loan restructuring [Line Items]
Financing receivable, loan restructuring, amortized cost basis	174	216	220
Adjustable-rate and other
financing receivable, loan restructuring [Line Items]
Financing receivable, loan restructuring, amortized cost basis	193	192	204
Adjustable-rate and other | Financial Asset, Not Past Due
financing receivable, loan restructuring [Line Items]
Financing receivable, loan restructuring, amortized cost basis	87	73	101
Adjustable-rate and other | One month past due
financing receivable, loan restructuring [Line Items]
Financing receivable, loan restructuring, amortized cost basis	24	25	23
Adjustable-rate and other | Two months past due
financing receivable, loan restructuring [Line Items]
Financing receivable, loan restructuring, amortized cost basis	16	19	17
Adjustable-rate and other | Three months or more past due or in foreclosure
financing receivable, loan restructuring [Line Items]
Financing receivable, loan restructuring, amortized cost basis	$ 66	$ 75	$ 63