FINANCING ACTIVITIES - Dividend Restrictions Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Dividends Payable [Line Items]
Maximum percentage debt to capitalization	67.50%
Restricted net assets	$ 20,500
Retained earnings available to pay dividends	15,100
Dividends paid on common stock	2,008	$ 1,898	$ 1,752
Retained Earnings
Dividends Payable [Line Items]
Dividends paid on common stock	$ 2,000	1,900	1,800
I&M
Dividends Payable [Line Items]
Maximum percentage debt to capitalization	67.50%
Dividends paid on common stock	$ 50	150	212
AEP Texas
Dividends Payable [Line Items]
Maximum percentage debt to capitalization	67.50%
Dividends paid on common stock	$ 0	350	0
APCo
Dividends Payable [Line Items]
Maximum percentage debt to capitalization	67.50%
Dividends paid on common stock	$ 50	75	0
SWEPCo
Dividends Payable [Line Items]
Maximum percentage debt to capitalization	67.50%
Dividends paid on common stock	$ 0	250	175
PSO
Dividends Payable [Line Items]
Maximum percentage debt to capitalization	67.50%
Dividends paid on common stock	$ 0	$ 140	$ 52
AEPTCo
Dividends Payable [Line Items]
Maximum percentage debt to capitalization	67.50%