FINANCING ACTIVITIES - Schedule of Nonutility Money Pool Activity (Details) - AEP TEXAS INC. - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2026	Dec. 31, 2025
Short-Term Debt [Line Items]
Advances to Affiliates	$ 112	$ 7
Nonutility
Short-Term Debt [Line Items]
Maximum Loans	7
Average Loans	7
Nonutility | Related Party
Short-Term Debt [Line Items]
Advances to Affiliates	$ 7