FINANCING ACTIVITIES - Schedule of Direct Borrowing Activity (Details) - Direct Borrowing - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
AEP TRANSMISSION COMPANY, LLC
Short-Term Debt [Line Items]
Maximum Borrowings	$ 49.4	$ 42.7
Maximum Loans	148.5	158.1
Average Borrowings	14.9	18.0
Average Loans	57.0	64.2
Borrowings	0.0	42.7
Loans	20.4	0.0
Authorized Short-term Borrowing Limit	0.0	0.0
SWTCo
Short-Term Debt [Line Items]
Maximum Borrowings	1.9	1.6
Maximum Loans	0.0	0.0
Average Borrowings	1.8	1.6
Average Loans	0.0	0.0
Borrowings	1.8	1.7
Loans	0.0	0.0
Authorized Short-term Borrowing Limit	$ 50.0	$ 50.0