v3.25.2
FAIR VALUE MEASUREMENTS - Debt Fair Value (Details) - USD ($)
$ in Millions
Jun. 30, 2025
Dec. 31, 2024
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Book Value $ 44,525.5 $ 42,642.8
Fair Value 41,138.3 38,964.7
AEP Texas    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Book Value 6,832.3 6,441.6
Fair Value 6,303.0 5,831.4
AEPTCo    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Book Value 6,098.5 5,768.1
Fair Value 5,346.8 4,853.1
APCo    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Book Value 5,772.0 5,660.3
Fair Value 5,577.2 5,346.0
I&M    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Book Value 3,510.9 3,494.3
Fair Value 3,250.4 3,153.8
OPCo    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Book Value 3,717.1 3,715.7
Fair Value 3,138.3 3,203.4
PSO    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Book Value 3,524.0 2,855.6
Fair Value 3,310.8 2,562.1
SWEPCo    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Book Value 3,983.0 3,980.8
Fair Value $ 3,593.4 $ 3,431.5