Mortgage Loans - Subsequent Defaults of Single-Family Restructured Loans Involving Borrowers Experiencing Financial Difficulty (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Single Family
financing receivable, loan restructuring [Line Items]
Financing receivable, restructured loans that defaulted, amortized cost basis	$ 6,471	$ 5,119	$ 3,834
Single Family | payment delay [Member]
financing receivable, loan restructuring [Line Items]
Financing receivable, restructured loans that defaulted, amortized cost basis	3,686	3,427	2,615
Single Family | payment delay and term extension [Member]
financing receivable, loan restructuring [Line Items]
Financing receivable, restructured loans that defaulted, amortized cost basis	2,593	1,671	911
Single Family | payment delay, interest rate reduction, and term extension [Member]
financing receivable, loan restructuring [Line Items]
Financing receivable, restructured loans that defaulted, amortized cost basis	192	21	308
20- and 30-year or more, amortizing fixed-rate
financing receivable, loan restructuring [Line Items]
Financing receivable, restructured loans that defaulted, amortized cost basis	6,347	4,977	3,695
20- and 30-year or more, amortizing fixed-rate | payment delay [Member]
financing receivable, loan restructuring [Line Items]
Financing receivable, restructured loans that defaulted, amortized cost basis	3,567	3,287	2,488
20- and 30-year or more, amortizing fixed-rate | payment delay and term extension [Member]
financing receivable, loan restructuring [Line Items]
Financing receivable, restructured loans that defaulted, amortized cost basis	2,588	1,669	905
20- and 30-year or more, amortizing fixed-rate | payment delay, interest rate reduction, and term extension [Member]
financing receivable, loan restructuring [Line Items]
Financing receivable, restructured loans that defaulted, amortized cost basis	192	21	302
15-year or less, amortizing fixed-rate
financing receivable, loan restructuring [Line Items]
Financing receivable, restructured loans that defaulted, amortized cost basis	94	104	97
15-year or less, amortizing fixed-rate | payment delay [Member]
financing receivable, loan restructuring [Line Items]
Financing receivable, restructured loans that defaulted, amortized cost basis	93	104	97
15-year or less, amortizing fixed-rate | payment delay and term extension [Member]
financing receivable, loan restructuring [Line Items]
Financing receivable, restructured loans that defaulted, amortized cost basis	1	0	0
15-year or less, amortizing fixed-rate | payment delay, interest rate reduction, and term extension [Member]
financing receivable, loan restructuring [Line Items]
Financing receivable, restructured loans that defaulted, amortized cost basis	0	0	0
Adjustable-rate and other
financing receivable, loan restructuring [Line Items]
Financing receivable, restructured loans that defaulted, amortized cost basis	30	38	42
Adjustable-rate and other | payment delay [Member]
financing receivable, loan restructuring [Line Items]
Financing receivable, restructured loans that defaulted, amortized cost basis	26	36	30
Adjustable-rate and other | payment delay and term extension [Member]
financing receivable, loan restructuring [Line Items]
Financing receivable, restructured loans that defaulted, amortized cost basis	4	2	6
Adjustable-rate and other | payment delay, interest rate reduction, and term extension [Member]
financing receivable, loan restructuring [Line Items]
Financing receivable, restructured loans that defaulted, amortized cost basis	$ 0	$ 0	$ 6