REVENUE FROM CONTRACTS WITH CUSTOMERS - Affiliate Accounts Receivable (Details) - Related Party - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
AEP TEXAS INC.
Disaggregation of Revenue [Line Items]
Affiliated Companies	$ 0.0	$ 0.0
AEP TRANSMISSION COMPANY, LLC
Disaggregation of Revenue [Line Items]
Affiliated Companies	131.6	123.2
APPALACHIAN POWER COMPANY
Disaggregation of Revenue [Line Items]
Affiliated Companies	83.7	71.7
INDIANA MICHIGAN POWER COMPANY
Disaggregation of Revenue [Line Items]
Affiliated Companies	55.0	44.0
OHIO POWER COMPANY
Disaggregation of Revenue [Line Items]
Affiliated Companies	63.6	70.1
PUBLIC SERVICE COMPANY OF OKLAHOMA
Disaggregation of Revenue [Line Items]
Affiliated Companies	13.0	12.4
SOUTHWESTERN ELECTRIC POWER COMPANY
Disaggregation of Revenue [Line Items]
Affiliated Companies	$ 21.4	$ 27.4