FAIR VALUE MEASUREMENTS - Debt Fair Value (Details) - USD ($) $ in Millions	Mar. 31, 2025	Dec. 31, 2024
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Book Value	$ 42,989.8	$ 42,642.8
Fair Value	39,687.2	38,964.7
AEP Texas
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Book Value	6,830.7	6,441.6
Fair Value	6,256.7	5,831.4
AEPTCo
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Book Value	5,719.0	5,768.1
Fair Value	4,850.2	4,853.1
APCo
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Book Value	5,647.5	5,660.3
Fair Value	5,362.5	5,346.0
I&M
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Book Value	3,471.6	3,494.3
Fair Value	3,154.9	3,153.8
OPCo
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Book Value	3,716.4	3,715.7
Fair Value	3,227.8	3,203.4
PSO
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Book Value	2,731.2	2,855.6
Fair Value	2,486.9	2,562.1
SWEPCo
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Book Value	3,981.4	3,980.8
Fair Value	$ 3,569.8	$ 3,431.5