PROPERTY, PLANT, AND EQUIPMENT - Allowance for Equity Funds and Borrowed Funds Used During Construction (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Property, Plant and Equipment [Line Items]
Allowance for equity funds used during construction	$ 211.0	$ 174.9	$ 133.7
Borrowed funds used during construction	129.8	117.3	63.0
AEP TEXAS INC.
Property, Plant and Equipment [Line Items]
Allowance for equity funds used during construction	45.9	28.4	19.7
Borrowed funds used during construction	30.7	23.4	11.5
AEP TRANSMISSION COMPANY, LLC
Property, Plant and Equipment [Line Items]
Allowance for equity funds used during construction	89.4	83.2	70.7
Borrowed funds used during construction	33.7	31.4	22.4
APPALACHIAN POWER COMPANY
Property, Plant and Equipment [Line Items]
Allowance for equity funds used during construction	16.1	11.9	11.7
Borrowed funds used during construction	10.5	14.1	6.5
INDIANA MICHIGAN POWER COMPANY
Property, Plant and Equipment [Line Items]
Allowance for equity funds used during construction	13.3	10.9	9.8
Borrowed funds used during construction	9.2	7.7	5.7
OHIO POWER COMPANY
Property, Plant and Equipment [Line Items]
Allowance for equity funds used during construction	23.4	17.1	13.9
Borrowed funds used during construction	12.8	14.0	6.7
PUBLIC SERVICE COMPANY OF OKLAHOMA
Property, Plant and Equipment [Line Items]
Allowance for equity funds used during construction	7.4	8.4	1.5
Borrowed funds used during construction	9.7	5.2	2.7
SOUTHWESTERN ELECTRIC POWER COMPANY
Property, Plant and Equipment [Line Items]
Allowance for equity funds used during construction	13.5	11.5	4.9
Borrowed funds used during construction	$ 15.1	$ 9.8	$ 4.3