v3.26.3
DERIVATIVES AND HEDGING - Narrative (Details) - USD ($)
$ in Millions
9 Months Ended
Sep. 30, 2026
Dec. 31, 2025
Derivative Instruments and Hedging Activities Disclosures [Line Items]    
Cash collateral received from third-parties $ 116 $ 83
Fair value of derivative liabilities subject to cross acceleration provisions 30 30
Fair value of derivative liabilities subject to cross default provisions 207 183
APCo    
Derivative Instruments and Hedging Activities Disclosures [Line Items]    
Fair value of derivative liabilities subject to cross default provisions 15 2
INDIANA MICHIGAN POWER COMPANY    
Derivative Instruments and Hedging Activities Disclosures [Line Items]    
Fair value of derivative liabilities subject to cross default provisions 1  
PSO    
Derivative Instruments and Hedging Activities Disclosures [Line Items]    
Fair value of derivative liabilities subject to cross default provisions 31 27
SWEPCo    
Derivative Instruments and Hedging Activities Disclosures [Line Items]    
Fair value of derivative liabilities subject to cross default provisions $ 10 $ 10
Commodity    
Derivative Instruments and Hedging Activities Disclosures [Line Items]    
Maximum length of time to hedge exposure to variability 9 years  
Cross acceleration provisions maximum third party obligation amount $ 50  
Cross default provisions maximum third party obligation amount $ 50