SIGNIFICANT ACCOUNTING MATTERS - Earnings per Share (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Accounting Policies [Abstract]
Earnings Attributable to AEP Common Shareholders, Basic	$ 972.0	$ 959.6	$ 2,998.0	$ 2,303.0
Earnings Attributable to AEP Common Shareholders, Diluted	$ 972.0	$ 959.6	$ 2,998.0	$ 2,303.0
Weighted-Average Number of Basic AEP Common Shares Outstanding (in shares)	534,867,357	532,208,876	534,186,206	529,230,818
Weighted-Average Number of Basic AEP Common Shares Outstanding (in dollars per share)	$ 1.82	$ 1.80	$ 5.61	$ 4.35
Weighted-Average Dilutive Effect (in shares)	3,100,000	1,400,000	2,200,000	1,300,000
Weighted-Average Dilutive Effect (in dollars per share)	$ (0.01)	$ 0	$ (0.02)	$ (0.01)
Weighted-Average Number of Diluted AEP Common Shares Outstanding (in shares)	537,988,799	533,600,842	536,364,715	530,456,985
Weighted-Average Number of Diluted AEP Common Shares Outstanding (in dollars per share)	$ 1.81	$ 1.80	$ 5.59	$ 4.34