FINANCING ACTIVITIES - Dividend Restrictions Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Dividends Payable [Line Items]
Maximum percentage debt to capitalization	67.50%
Restricted net assets	$ 17,400.0
Retained earnings available to pay dividends	8,600.0
Dividends paid on common stock	1,903.9	$ 1,760.4	$ 1,645.2
Retained Earnings
Dividends Payable [Line Items]
Dividends paid on common stock	$ 1,900.0	1,800.0	1,600.0
INDIANA MICHIGAN POWER COMPANY
Dividends Payable [Line Items]
Maximum percentage debt to capitalization	67.50%
Dividends paid on common stock	$ 150.0	212.5	110.0
AEP TEXAS INC.
Dividends Payable [Line Items]
Maximum percentage debt to capitalization	67.50%
Dividends paid on common stock	$ 350.0	0.0	0.0
APPALACHIAN POWER COMPANY
Dividends Payable [Line Items]
Maximum percentage debt to capitalization	67.50%
Dividends paid on common stock	$ 75.0	0.0	37.5
SOUTHWESTERN ELECTRIC POWER COMPANY
Dividends Payable [Line Items]
Maximum percentage debt to capitalization	67.50%
Dividends paid on common stock	$ 250.0	175.0	105.0
PUBLIC SERVICE COMPANY OF OKLAHOMA
Dividends Payable [Line Items]
Maximum percentage debt to capitalization	67.50%
Dividends paid on common stock	$ 140.0	$ 52.5	$ 45.0
AEP TRANSMISSION COMPANY, LLC
Dividends Payable [Line Items]
Maximum percentage debt to capitalization	67.50%