LEASES - Lease Rental Costs (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Lessee, Lease, Description [Line Items]
Operating Lease Cost	$ 145.9	$ 149.9	$ 157.5
Finance Lease Cost:
Amortization of Right-of-Use Assets	63.7	69.1	205.5
Interest on Lease Liabilities	11.9	11.9	13.4
Total Lease Rental Costs	221.5	230.9	376.4
AEP TEXAS INC.
Lessee, Lease, Description [Line Items]
Operating Lease Cost	32.3	34.0	18.4
Finance Lease Cost:
Amortization of Right-of-Use Assets	7.5	7.4	6.8
Interest on Lease Liabilities	1.4	1.4	1.3
Total Lease Rental Costs	41.2	42.8	26.5
AEP TRANSMISSION COMPANY, LLC
Lessee, Lease, Description [Line Items]
Operating Lease Cost	1.3	1.3	1.1
Finance Lease Cost:
Amortization of Right-of-Use Assets	0.0	0.0	0.0
Interest on Lease Liabilities	0.0	0.0	0.0
Total Lease Rental Costs	1.3	1.3	1.1
APPALACHIAN POWER COMPANY
Lessee, Lease, Description [Line Items]
Operating Lease Cost	18.4	18.5	17.9
Finance Lease Cost:
Amortization of Right-of-Use Assets	8.7	8.3	7.9
Interest on Lease Liabilities	1.5	1.8	2.0
Total Lease Rental Costs	28.6	28.6	27.8
INDIANA MICHIGAN POWER COMPANY
Lessee, Lease, Description [Line Items]
Operating Lease Cost	19.6	19.6	29.5
Finance Lease Cost:
Amortization of Right-of-Use Assets	7.2	7.3	78.7
Interest on Lease Liabilities	2.2	2.5	3.1
Total Lease Rental Costs	29.0	29.4	111.3
OHIO POWER COMPANY
Lessee, Lease, Description [Line Items]
Operating Lease Cost	16.8	17.3	16.9
Finance Lease Cost:
Amortization of Right-of-Use Assets	5.3	5.0	4.9
Interest on Lease Liabilities	0.9	0.9	0.8
Total Lease Rental Costs	23.0	23.2	22.6
PUBLIC SERVICE COMPANY OF OKLAHOMA
Lessee, Lease, Description [Line Items]
Operating Lease Cost	13.5	13.5	11.8
Finance Lease Cost:
Amortization of Right-of-Use Assets	3.3	3.3	3.2
Interest on Lease Liabilities	0.7	0.7	0.6
Total Lease Rental Costs	17.5	17.5	15.6
SOUTHWESTERN ELECTRIC POWER COMPANY
Lessee, Lease, Description [Line Items]
Operating Lease Cost	17.8	17.5	15.3
Finance Lease Cost:
Amortization of Right-of-Use Assets	13.0	19.9	10.8
Interest on Lease Liabilities	1.6	1.4	2.1
Total Lease Rental Costs	$ 32.4	$ 38.8	$ 28.2