v3.26.1
Fair Value - Levels Hierarchy (Details) - USD ($)
$ in Millions
Mar. 31, 2026
Dec. 31, 2025
Assets:    
Available-for-sale securities $ 12,424 $ 375
Mortgage loans held for investment, net of allowance for loan losses 5,547 5,464
Derivative assets at fair value 352 177
Derivative assets, gross amount offset (136) (199)
Liabilities:    
Derivative liabilities 676 152
Fannie Mae    
Liabilities:    
Long-term debt 265 256
Consolidated Trusts    
Liabilities:    
Long-term debt 13,707 15,060
Quoted Prices in Active Markets for Identical Assets (Level 1)    
Assets:    
Trading securities 44,406 55,205
Available-for-sale securities 11,906 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 18,664 14,282
Available-for-sale securities 187 34
Derivative assets at fair value 418 304
Liabilities:    
Derivative liabilities 1,959 1,387
Significant Other Observable Inputs (Level 2) | Fannie Mae    
Liabilities:    
Long-term debt 131,354 104,784
Significant Other Observable Inputs (Level 2) | Consolidated Trusts    
Liabilities:    
Long-term debt 3,653,910 3,701,675
Significant Unobservable Inputs (Level 3)    
Assets:    
Trading securities 26 27
Available-for-sale securities 331 341
Derivative assets at fair value 70 72
Liabilities:    
Derivative liabilities 16 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 230 235
Recurring    
Assets:    
Trading securities 63,096 69,514
Available-for-sale securities 12,424 375
Mortgage loans held for investment, net of allowance for loan losses 5,547 5,464
Derivative assets at fair value 352 177
Derivative assets, gross amount offset (136) (199)
Total assets at fair value 81,419 75,530
Liabilities:    
Long-term debt 13,972 15,316
Derivative liabilities 676 152
Derivative liabilities, gross amount offset (1,299) (1,242)
Total liabilities at fair value 14,648 15,468
Recurring | Fannie Mae    
Liabilities:    
Long-term debt 265 256
Recurring | Consolidated Trusts    
Liabilities:    
Long-term debt 13,707 15,060
Recurring | Mortgage-related securities    
Assets:    
Trading securities 18,672 14,291
Available-for-sale securities 518 375
Recurring | Non-mortgage-related securities    
Assets:    
Trading securities 44,424 55,223
Available-for-sale securities 11,906 0
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1)    
Assets:    
Trading securities 44,406 55,205
Available-for-sale securities 11,906 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 56,312 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 44,406 55,205
Available-for-sale securities 11,906 0
Recurring | Significant Other Observable Inputs (Level 2)    
Assets:    
Trading securities 18,664 14,282
Available-for-sale securities 187 34
Mortgage loans held for investment, net of allowance for loan losses 5,146 5,076
Derivative assets at fair value 418 304
Total assets at fair value 24,415 19,696
Liabilities:    
Long-term debt 13,619 14,969
Derivative liabilities 1,959 1,387
Total liabilities at fair value 15,578 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 13,619 14,969
Recurring | Significant Other Observable Inputs (Level 2) | Mortgage-related securities    
Assets:    
Trading securities 18,646 14,264
Available-for-sale securities 187 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 331 341
Mortgage loans held for investment, net of allowance for loan losses 401 388
Derivative assets at fair value 70 72
Total assets at fair value 828 828
Liabilities:    
Long-term debt 353 347
Derivative liabilities 16 7
Total liabilities at fair value 369 354
Recurring | Significant Unobservable Inputs (Level 3) | Fannie Mae    
Liabilities:    
Long-term debt 265 256
Recurring | Significant Unobservable Inputs (Level 3) | Consolidated Trusts    
Liabilities:    
Long-term debt 88 91
Recurring | Significant Unobservable Inputs (Level 3) | Mortgage-related securities    
Assets:    
Trading securities 26 27
Available-for-sale securities 331 341
Recurring | Significant Unobservable Inputs (Level 3) | Non-mortgage-related securities    
Assets:    
Trading securities 0 0
Available-for-sale securities $ 0 $ 0