SIGNIFICANT ACCOUNTING MATTERS - Earnings per Share (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
Accounting Policies [Abstract]
Earnings Attributable to AEP Common Shareholders, Basic	$ 800.2	$ 1,003.1
Earnings Attributable to AEP Common Shareholders, Diluted	$ 800.2	$ 1,003.1
Weighted-Average Number of Basic AEP Common Shares Outstanding (in shares)	533,391,487	526,552,036
Weighted-Average Number of Basic AEP Common Shares Outstanding (in dollars per share)	$ 1.50	$ 1.91
Weighted-Average Dilutive Effect of Stock-Based Awards (in shares)	1,300,000	1,000,000.0
Weighted-Average Dilutive Effect of Stock-Based Awards (in dollars per share)	$ 0	$ (0.01)
Weighted-Average Number of Diluted AEP Common Shares Outstanding (in shares)	534,663,493	527,596,395
Weighted-Average Number of Diluted AEP Common Shares Outstanding (in dollars per share)	$ 1.50	$ 1.90