v3.26.1
Fair Value - Levels Hierarchy (Details) - USD ($)
$ in Millions
Jun. 30, 2026
Dec. 31, 2025
Assets:    
Available-for-sale securities $ 38,874 $ 375
Mortgage loans held for investment, net of allowance for loan losses 5,983 5,464
Derivative assets at fair value 386 177
Derivative assets, gross amount offset (38) (199)
Liabilities:    
Derivative liabilities 270 152
Fannie Mae    
Liabilities:    
Long-term debt 264 256
Consolidated Trusts    
Liabilities:    
Long-term debt 14,557 15,060
Quoted Prices in Active Markets for Identical Assets (Level 1)    
Assets:    
Trading securities 39,661 55,205
Available-for-sale securities 38,265 0
Derivative assets at fair value 0 0
Liabilities:    
Derivative liabilities 0 0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Fannie Mae    
Liabilities:    
Long-term debt 0 0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Consolidated Trusts    
Liabilities:    
Long-term debt 0 0
Significant Other Observable Inputs (Level 2)    
Assets:    
Trading securities 16,208 14,282
Available-for-sale securities 289 34
Derivative assets at fair value 348 304
Liabilities:    
Derivative liabilities 1,646 1,387
Significant Other Observable Inputs (Level 2) | Fannie Mae    
Liabilities:    
Long-term debt 148,871 104,784
Significant Other Observable Inputs (Level 2) | Consolidated Trusts    
Liabilities:    
Long-term debt 3,637,079 3,701,675
Significant Unobservable Inputs (Level 3)    
Assets:    
Trading securities 26 27
Available-for-sale securities 320 341
Derivative assets at fair value 76 72
Liabilities:    
Derivative liabilities 7 7
Significant Unobservable Inputs (Level 3) | Fannie Mae    
Liabilities:    
Long-term debt 599 602
Significant Unobservable Inputs (Level 3) | Consolidated Trusts    
Liabilities:    
Long-term debt 215 235
Recurring    
Assets:    
Trading securities 55,895 69,514
Available-for-sale securities 38,874 375
Mortgage loans held for investment, net of allowance for loan losses 5,983 5,464
Derivative assets at fair value 386 177
Derivative assets, gross amount offset (38) (199)
Total assets at fair value 101,138 75,530
Liabilities:    
Long-term debt 14,821 15,316
Derivative liabilities 270 152
Derivative liabilities, gross amount offset (1,383) (1,242)
Total liabilities at fair value 15,091 15,468
Recurring | Fannie Mae    
Liabilities:    
Long-term debt 264 256
Recurring | Consolidated Trusts    
Liabilities:    
Long-term debt 14,557 15,060
Recurring | Mortgage-related securities    
Assets:    
Trading securities 16,216 14,291
Available-for-sale securities 609 375
Recurring | Non-mortgage-related securities    
Assets:    
Trading securities 39,679 55,223
Available-for-sale securities 38,265 0
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1)    
Assets:    
Trading securities 39,661 55,205
Available-for-sale securities 38,265 0
Mortgage loans held for investment, net of allowance for loan losses 0 0
Derivative assets at fair value 0 0
Total assets at fair value 77,926 55,205
Liabilities:    
Long-term debt 0 0
Derivative liabilities 0 0
Total liabilities at fair value 0 0
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Fannie Mae    
Liabilities:    
Long-term debt 0 0
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Consolidated Trusts    
Liabilities:    
Long-term debt 0 0
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Mortgage-related securities    
Assets:    
Trading securities 0 0
Available-for-sale securities 0 0
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Non-mortgage-related securities    
Assets:    
Trading securities 39,661 55,205
Available-for-sale securities 38,265 0
Recurring | Significant Other Observable Inputs (Level 2)    
Assets:    
Trading securities 16,208 14,282
Available-for-sale securities 289 34
Mortgage loans held for investment, net of allowance for loan losses 5,616 5,076
Derivative assets at fair value 348 304
Total assets at fair value 22,461 19,696
Liabilities:    
Long-term debt 14,475 14,969
Derivative liabilities 1,646 1,387
Total liabilities at fair value 16,121 16,356
Recurring | Significant Other Observable Inputs (Level 2) | Fannie Mae    
Liabilities:    
Long-term debt 0 0
Recurring | Significant Other Observable Inputs (Level 2) | Consolidated Trusts    
Liabilities:    
Long-term debt 14,475 14,969
Recurring | Significant Other Observable Inputs (Level 2) | Mortgage-related securities    
Assets:    
Trading securities 16,190 14,264
Available-for-sale securities 289 34
Recurring | Significant Other Observable Inputs (Level 2) | Non-mortgage-related securities    
Assets:    
Trading securities 18 18
Available-for-sale securities 0 0
Recurring | Significant Unobservable Inputs (Level 3)    
Assets:    
Trading securities 26 27
Available-for-sale securities 320 341
Mortgage loans held for investment, net of allowance for loan losses 367 388
Derivative assets at fair value 76 72
Total assets at fair value 789 828
Liabilities:    
Long-term debt 346 347
Derivative liabilities 7 7
Total liabilities at fair value 353 354
Recurring | Significant Unobservable Inputs (Level 3) | Fannie Mae    
Liabilities:    
Long-term debt 264 256
Recurring | Significant Unobservable Inputs (Level 3) | Consolidated Trusts    
Liabilities:    
Long-term debt 82 91
Recurring | Significant Unobservable Inputs (Level 3) | Mortgage-related securities    
Assets:    
Trading securities 26 27
Available-for-sale securities 320 341
Recurring | Significant Unobservable Inputs (Level 3) | Non-mortgage-related securities    
Assets:    
Trading securities 0 0
Available-for-sale securities $ 0 $ 0