v3.25.4
Short-Term and Long-Term Debt - Characteristics of Debt (Details) - USD ($)
$ in Millions
Dec. 31, 2025
Dec. 31, 2024
Long-Term Debt by Year of Maturity [Abstract]    
Total long-term debt $ 4,155,891 $ 4,216,909
Assuming Callable Debt Redeemed at Next Available Call Date    
Long-Term Debt by Year of Maturity [Abstract]    
Total long-term debt 4,155,891  
Fannie Mae    
Long-Term Debt [Line Items]    
Face amount 130,000 143,100
Long-Term Debt by Year of Maturity [Abstract]    
2026 41,035  
2027 13,053  
2028 8,896  
2029 6,840  
2030 27,296  
Thereafter 5,631  
Total long-term debt 102,751 128,234
Fannie Mae | Zero-coupon debt    
Long-Term Debt [Line Items]    
Face amount $ 24,800 $ 11,500
Effective interest rate 3.67% 4.36%
Fannie Mae | Callable    
Long-Term Debt [Line Items]    
Outstanding debt $ 35,400 $ 41,000
Fannie Mae | Assuming Callable Debt Redeemed at Next Available Call Date    
Long-Term Debt by Year of Maturity [Abstract]    
2026 68,344  
2027 14,390  
2028 1,443  
2029 2,829  
2030 14,165  
Thereafter 1,580  
Total long-term debt 102,751  
Consolidated Trusts    
Long-Term Debt by Year of Maturity [Abstract]    
Total long-term debt 4,053,140 $ 4,088,675
Consolidated Trusts | Assuming Callable Debt Redeemed at Next Available Call Date    
Long-Term Debt by Year of Maturity [Abstract]    
Total long-term debt $ 4,053,140