v3.25.4
Short-Term and Long-Term Debt - Long-Term Debt (Details) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2025
Dec. 31, 2024
Long-Term Debt [Line Items]    
Long-term debt, outstanding $ 4,155,891 $ 4,216,909
Long-term debt, weighted-average interest rate 3.16% 2.97%
Fannie Mae    
Long-Term Debt [Line Items]    
Long-term debt, outstanding $ 102,751 $ 128,234
Long-term debt, weighted-average interest rate 3.89% 3.30%
Net unamortized discount, fair value adjustments and other cost basis adjustments $ 2,600 $ 3,600
Fannie Mae | Senior Fixed    
Long-Term Debt [Line Items]    
Long-term debt, outstanding $ 64,688 $ 93,495
Long-term debt, weighted-average interest rate 3.70% 2.66%
Fannie Mae | Benchmark notes and bonds    
Long-Term Debt [Line Items]    
Long-term debt, outstanding $ 26,649 $ 44,655
Long-term debt, weighted-average interest rate 4.16% 2.87%
Fannie Mae | Medium-term notes    
Long-Term Debt [Line Items]    
Long-term debt, outstanding $ 31,430 $ 42,208
Long-term debt, weighted-average interest rate 3.25% 2.21%
Fannie Mae | Medium-term notes | Minimum    
Long-Term Debt [Line Items]    
Contractual maturity term 1 year 1 year
Fannie Mae | Medium-term notes | Maximum    
Long-Term Debt [Line Items]    
Contractual maturity term 10 years 10 years
Fannie Mae | Other    
Long-Term Debt [Line Items]    
Long-term debt, outstanding $ 6,609 $ 6,632
Long-term debt, weighted-average interest rate 3.87% 3.98%
Contractual maturity term 10 years 10 years
Fannie Mae | Senior floating    
Long-Term Debt [Line Items]    
Long-term debt, outstanding $ 38,063 $ 34,739
Long-term debt, weighted-average interest rate 4.23% 5.07%
Fannie Mae | Medium-term notes    
Long-Term Debt [Line Items]    
Long-term debt, outstanding $ 36,437 $ 32,435
Long-term debt, weighted-average interest rate 3.93% 4.67%
Fannie Mae | Other    
Long-Term Debt [Line Items]    
Long-term debt, outstanding $ 1,626 $ 2,304
Long-term debt, weighted-average interest rate 10.99% 10.68%
Consolidated Trusts    
Long-Term Debt [Line Items]    
Long-term debt, outstanding $ 4,053,140 $ 4,088,675
Long-term debt, weighted-average interest rate 3.14% 2.96%