v3.26.1
Fair Value - Fair Value Option (Details) - USD ($)
$ in Millions
3 Months Ended
Mar. 31, 2026
Dec. 31, 2025
Fair Value, Option, Quantitative Disclosures [Line Items]    
Mortgage loans held for investment, net of allowance for loan losses $ 5,547 $ 5,464
Fair value of nonaccrual loans $ 28 30
Serious delinquency, days past due 90 days  
Fair value of loans that are 90 days or more past due $ 20 26
Fannie Mae    
Fair Value, Option, Quantitative Disclosures [Line Items]    
Long-term debt 265 256
Consolidated Trusts    
Fair Value, Option, Quantitative Disclosures [Line Items]    
Long-term debt 13,707 15,060
Loans    
Fair Value, Option, Quantitative Disclosures [Line Items]    
Mortgage loans held for investment, net of allowance for loan losses 5,547 5,464
Loans, unpaid principal balance 5,943 5,808
Long-term Debt | Fannie Mae    
Fair Value, Option, Quantitative Disclosures [Line Items]    
Long-term debt 265 256
Long-term debt, unpaid principal balance 250 250
Long-term Debt | Consolidated Trusts    
Fair Value, Option, Quantitative Disclosures [Line Items]    
Long-term debt 13,707 15,060
Long-term debt, unpaid principal balance $ 14,215 $ 15,516