v3.26.3
FINANCING ACTIVITIES - Financing Activities Subsequent Events (Details) - USD ($)
$ in Millions
1 Months Ended 9 Months Ended
Oct. 28, 2026
Sep. 30, 2026
Sep. 30, 2025
Debt Instrument [Line Items]      
Proceeds from issuance of debt   $ 7,092  
Retirement of long-term debt   1,834 $ 2,804
AEP Texas      
Debt Instrument [Line Items]      
Retirement of long-term debt   75 475
AEPTCo      
Debt Instrument [Line Items]      
Retirement of long-term debt   623 90
AEPTCo | Other Long-term Debt      
Debt Instrument [Line Items]      
Proceeds from issuance of debt   214  
Retirement of long-term debt   623  
I&M      
Debt Instrument [Line Items]      
Retirement of long-term debt   $ 94 $ 270
Subsequent Event | AEP Texas      
Debt Instrument [Line Items]      
Proceeds from contributed capital $ 450    
Subsequent Event | OPCo      
Debt Instrument [Line Items]      
Proceeds from contributed capital 210    
Subsequent Event | AEPTCo | Other Long-term Debt      
Debt Instrument [Line Items]      
Proceeds from issuance of debt 270    
Subsequent Event | I&M | Notes Payable      
Debt Instrument [Line Items]      
Proceeds from issuance of debt $ 110    
Interest rate (in percentage) 5.51%    
Retirement of long-term debt $ 7