FINANCING ACTIVITIES - Schedule of Maximum and Minimum Interest Rates for Funds Either Borrowed from or Loaned to Utility Money Pool (Details) - Utility	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
SOUTHWESTERN ELECTRIC POWER COMPANY
Short-Term Debt [Line Items]
Maximum Interest Rate	4.10%	4.76%
Minimum Interest Rate	3.53%	4.64%
OHIO POWER COMPANY
Short-Term Debt [Line Items]
Maximum Interest Rate	4.10%	4.76%
Minimum Interest Rate	3.53%	4.64%
INDIANA MICHIGAN POWER COMPANY
Short-Term Debt [Line Items]
Maximum Interest Rate	4.10%	4.76%
Minimum Interest Rate	3.53%	4.64%
AEP TEXAS INC.
Short-Term Debt [Line Items]
Maximum Interest Rate	4.10%	4.76%
Minimum Interest Rate	3.53%	4.64%
APPALACHIAN POWER COMPANY
Short-Term Debt [Line Items]
Maximum Interest Rate	4.10%	4.76%
Minimum Interest Rate	3.53%	4.64%
PUBLIC SERVICE COMPANY OF OKLAHOMA
Short-Term Debt [Line Items]
Maximum Interest Rate	4.10%	4.76%
Minimum Interest Rate	3.53%	4.64%
AEP TRANSMISSION COMPANY, LLC
Short-Term Debt [Line Items]
Maximum Interest Rate	4.10%	4.76%
Minimum Interest Rate	3.53%	4.64%