FINANCING ACTIVITIES - Schedule of Nonutility Money Pool Activity (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
AEP Texas
Short-Term Debt [Line Items]
Loans to the Nonutility Money Pool	$ 7	$ 7
SWEPCo
Short-Term Debt [Line Items]
Loans to the Nonutility Money Pool	23	2
Nonutility | AEP Texas
Short-Term Debt [Line Items]
Maximum Loans	7	7
Average Loans	7	7
Nonutility | AEP Texas | Related Party
Short-Term Debt [Line Items]
Loans to the Nonutility Money Pool	7	7
Nonutility | SWEPCo
Short-Term Debt [Line Items]
Maximum Loans	2	3
Average Loans	2	3
Nonutility | SWEPCo | Related Party
Short-Term Debt [Line Items]
Loans to the Nonutility Money Pool	$ 0	$ 2