v3.26.1
Financial Guarantees (Details) - USD ($)
$ in Millions
 3 Months Ended 12 Months Ended
Mar. 31, 2026
Dec. 31, 2025
Guarantor Obligations [Line Items]    
Outstanding balance of the guarantor advance $ 300 $ 400
Guarantees of Fannie Mae securities    
Guarantor Obligations [Line Items]    
Unpaid Principal Balance 97,155 98,370
Maximum exposure 97,155 98,370
Recognized Liability $ 0 $ 0
Maximum Remaining Term 36 years 36 years
Other Guarantees    
Guarantor Obligations [Line Items]    
Unpaid Principal Balance $ 61 $ 64
Maximum exposure 384 399
Recognized Liability $ 0 $ 0
Maximum Remaining Term 29 years 30 years
Single-family    
Guarantor Obligations [Line Items]    
Unpaid Principal Balance $ 36,572 $ 37,237
Maximum exposure 31,224 31,816
Recognized Liability 535 549
Single-family | Securitization products    
Guarantor Obligations [Line Items]    
Unpaid Principal Balance 29,528 30,025
Maximum exposure 24,180 24,604
Recognized Liability $ 446 $ 453
Maximum Remaining Term 39 years 40 years
Single-family | Other mortgage-related guarantees    
Guarantor Obligations [Line Items]    
Unpaid Principal Balance $ 7,044 $ 7,212
Maximum exposure 7,044 7,212
Recognized Liability $ 89 $ 96
Maximum Remaining Term 26 years 26 years
Multifamily    
Guarantor Obligations [Line Items]    
Unpaid Principal Balance $ 334,062 $ 342,575
Maximum exposure 302,174 309,499
Recognized Liability 3,745 3,961
Multifamily | Securitization products    
Guarantor Obligations [Line Items]    
Unpaid Principal Balance 324,122 332,572
Maximum exposure 292,245 299,507
Recognized Liability $ 3,426 $ 3,629
Maximum Remaining Term 34 years 34 years
Multifamily | Other mortgage-related guarantees    
Guarantor Obligations [Line Items]    
Unpaid Principal Balance $ 9,940 $ 10,003
Maximum exposure 9,929 9,992
Recognized Liability $ 319 $ 332
Maximum Remaining Term 33 years 33 years