LEASES - Supplemental Lease Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Weighted-Average Remaining Lease Term (years):
Operating Leases	12 years 9 months 18 days	12 years 6 months 29 days
Finance Leases	4 years 9 months 21 days	4 years 7 months 17 days
Weighted-Average Discount Rate:
Operating Leases	3.89%	3.73%
Finance Leases	6.43%	6.19%
Cash paid for amounts included in the measurement of lease liabilities:
Operating Cash Flows Used for Operating Leases	$ 143.9	$ 146.8
Operating Cash Flows Used for Finance Leases	12.0	11.9
Financing Cash Flows Used for Finance Leases	64.8	68.3	$ 309.5
Non-cash Acquisitions Under Operating Leases	$ 82.3	$ 99.8
AEP TEXAS INC.
Weighted-Average Remaining Lease Term (years):
Operating Leases	4 years 5 months 12 days	3 years 11 months 26 days
Finance Leases	5 years 14 days	5 years 1 month 17 days
Weighted-Average Discount Rate:
Operating Leases	4.29%	4.23%
Finance Leases	5.73%	5.27%
Cash paid for amounts included in the measurement of lease liabilities:
Operating Cash Flows Used for Operating Leases	$ 32.2	$ 33.6
Operating Cash Flows Used for Finance Leases	1.4	1.4
Financing Cash Flows Used for Finance Leases	7.5	7.4	6.8
Non-cash Acquisitions Under Operating Leases	$ 6.0	$ 12.4
AEP TRANSMISSION COMPANY, LLC
Weighted-Average Remaining Lease Term (years):
Operating Leases	2 years 3 months 14 days	2 years 9 months 3 days
Finance Leases	0 years	0 years
Weighted-Average Discount Rate:
Operating Leases	4.55%	3.61%
Finance Leases	0.00%	0.00%
Cash paid for amounts included in the measurement of lease liabilities:
Operating Cash Flows Used for Operating Leases	$ 1.3	$ 1.3
Operating Cash Flows Used for Finance Leases	0.0	0.0
Financing Cash Flows Used for Finance Leases	0.0	0.0
Non-cash Acquisitions Under Operating Leases	$ 1.0	$ 1.2
APPALACHIAN POWER COMPANY
Weighted-Average Remaining Lease Term (years):
Operating Leases	5 years 4 months 20 days	6 years 3 days
Finance Leases	4 years 1 month 2 days	4 years 1 month 28 days
Weighted-Average Discount Rate:
Operating Leases	4.20%	3.50%
Finance Leases	6.69%	7.04%
Cash paid for amounts included in the measurement of lease liabilities:
Operating Cash Flows Used for Operating Leases	$ 18.4	$ 18.3
Operating Cash Flows Used for Finance Leases	1.5	1.8
Financing Cash Flows Used for Finance Leases	8.7	8.3	7.9
Non-cash Acquisitions Under Operating Leases	$ 9.3	$ 15.7
INDIANA MICHIGAN POWER COMPANY
Weighted-Average Remaining Lease Term (years):
Operating Leases	4 years 5 months 4 days	4 years 6 months 10 days
Finance Leases	4 years 9 months 29 days	4 years 11 months 12 days
Weighted-Average Discount Rate:
Operating Leases	4.11%	3.89%
Finance Leases	9.07%	8.62%
Cash paid for amounts included in the measurement of lease liabilities:
Operating Cash Flows Used for Operating Leases	$ 19.6	$ 19.5
Operating Cash Flows Used for Finance Leases	2.2	2.5
Financing Cash Flows Used for Finance Leases	7.1	7.4	130.7
Non-cash Acquisitions Under Operating Leases	$ 15.0	$ 7.9
OHIO POWER COMPANY
Weighted-Average Remaining Lease Term (years):
Operating Leases	4 years 7 months 20 days	5 years 4 months 9 days
Finance Leases	4 years 6 months 29 days	4 years 11 months 19 days
Weighted-Average Discount Rate:
Operating Leases	4.17%	3.93%
Finance Leases	5.59%	5.32%
Cash paid for amounts included in the measurement of lease liabilities:
Operating Cash Flows Used for Operating Leases	$ 16.8	$ 17.0
Operating Cash Flows Used for Finance Leases	0.9	0.9
Financing Cash Flows Used for Finance Leases	5.3	5.0	4.9
Non-cash Acquisitions Under Operating Leases	$ 4.6	$ 10.2
PUBLIC SERVICE COMPANY OF OKLAHOMA
Weighted-Average Remaining Lease Term (years):
Operating Leases	23 years 8 months 4 days	23 years 10 months 6 days
Finance Leases	5 years 5 months 8 days	5 years 9 months 3 days
Weighted-Average Discount Rate:
Operating Leases	3.76%	3.72%
Finance Leases	5.48%	5.14%
Cash paid for amounts included in the measurement of lease liabilities:
Operating Cash Flows Used for Operating Leases	$ 12.5	$ 12.5
Operating Cash Flows Used for Finance Leases	0.7	0.7
Financing Cash Flows Used for Finance Leases	3.3	3.3	3.2
Non-cash Acquisitions Under Operating Leases	$ 2.5	$ 15.5
SOUTHWESTERN ELECTRIC POWER COMPANY
Weighted-Average Remaining Lease Term (years):
Operating Leases	21 years 11 months 19 days	22 years 6 months
Finance Leases	6 years 1 month 20 days	4 years 9 months 10 days
Weighted-Average Discount Rate:
Operating Leases	3.60%	3.53%
Finance Leases	5.73%	5.22%
Cash paid for amounts included in the measurement of lease liabilities:
Operating Cash Flows Used for Operating Leases	$ 16.8	$ 16.5
Operating Cash Flows Used for Finance Leases	1.7	1.4
Financing Cash Flows Used for Finance Leases	14.0	19.1	$ 10.8
Non-cash Acquisitions Under Operating Leases	$ 26.9	$ 14.3