STOCK-BASED COMPENSATION - Performance Shares and Reinvested Dividends (Details) - $ / shares shares in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awarded (in shares)	498	441	487
Weighted-Average Grant Date Fair Value (in dollars per share)	$ 123.42	$ 99.76	$ 98.63
Vesting Period (in years)	3 years	3 years	3 years
Performance Shares and AEP Career Shares (Reinvested Dividends Portion)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awarded (in shares)	53	66	81
Weighted-Average Grant Date Fair Value (in dollars per share)	$ 107.71	$ 91.75	$ 82.02