STOCK-BASED COMPENSATION - Performance Shares and AEP Career Shares (Details) - Performance Shares and AEP Career Shares (Reinvested Dividends Portion) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
AEP Common Stock Settlements for Performance Shares	$ 45	$ 38	$ 42
AEP Common Stock Settlements for Career Share Distributions	$ 13	$ 8	$ 8