FINANCING ACTIVITIES - Schedule of Proceeds on Sale of Receivables to AEP Credit (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
APPALACHIAN POWER COMPANY
Accounts, Notes, Loans and Financing Receivable [Line Items]
Proceeds from sale of receivables to AEP Credit	$ 543	$ 605
INDIANA MICHIGAN POWER COMPANY
Accounts, Notes, Loans and Financing Receivable [Line Items]
Proceeds from sale of receivables to AEP Credit	697	585
OHIO POWER COMPANY
Accounts, Notes, Loans and Financing Receivable [Line Items]
Proceeds from sale of receivables to AEP Credit	912	860
PUBLIC SERVICE COMPANY OF OKLAHOMA
Accounts, Notes, Loans and Financing Receivable [Line Items]
Proceeds from sale of receivables to AEP Credit	412	375
SOUTHWESTERN ELECTRIC POWER COMPANY
Accounts, Notes, Loans and Financing Receivable [Line Items]
Proceeds from sale of receivables to AEP Credit	$ 421	$ 428