BENEFIT PLANS - Schedule of Amounts Included on the Balance Sheets (Details) - USD ($) $ in Millions	Dec. 31, 2025	Dec. 31, 2024
Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Other Noncurrent Assets - Employee Benefits and Pension Assets	$ 0	$ 0
Other Current Liabilities – Accrued Short-term Benefit Liability	(6)	(5)
Other Noncurrent Liabilities – Accrued Long-term Benefit Liability	(78)	(201)
Funded (Underfunded) Status	(84)	(206)
Pension Plans | AEP TEXAS INC.
Defined Benefit Plan Disclosure [Line Items]
Other Noncurrent Assets - Employee Benefits and Pension Assets	0	0
Other Current Liabilities – Accrued Short-term Benefit Liability	0	(1)
Other Noncurrent Liabilities – Accrued Long-term Benefit Liability	(24)	(34)
Funded (Underfunded) Status	(24)	(35)
Pension Plans | APPALACHIAN POWER COMPANY
Defined Benefit Plan Disclosure [Line Items]
Other Noncurrent Assets - Employee Benefits and Pension Assets	43	35
Other Current Liabilities – Accrued Short-term Benefit Liability	0	0
Other Noncurrent Liabilities – Accrued Long-term Benefit Liability	0	0
Funded (Underfunded) Status	43	35
Pension Plans | INDIANA MICHIGAN POWER COMPANY
Defined Benefit Plan Disclosure [Line Items]
Other Noncurrent Assets - Employee Benefits and Pension Assets	67	58
Other Current Liabilities – Accrued Short-term Benefit Liability	0	0
Other Noncurrent Liabilities – Accrued Long-term Benefit Liability	(1)	(1)
Funded (Underfunded) Status	66	57
Pension Plans | OHIO POWER COMPANY
Defined Benefit Plan Disclosure [Line Items]
Other Noncurrent Assets - Employee Benefits and Pension Assets	35	30
Other Current Liabilities – Accrued Short-term Benefit Liability	0	0
Other Noncurrent Liabilities – Accrued Long-term Benefit Liability	0	0
Funded (Underfunded) Status	35	30
Pension Plans | PUBLIC SERVICE COMPANY OF OKLAHOMA
Defined Benefit Plan Disclosure [Line Items]
Other Noncurrent Assets - Employee Benefits and Pension Assets	16	11
Other Current Liabilities – Accrued Short-term Benefit Liability	0	0
Other Noncurrent Liabilities – Accrued Long-term Benefit Liability	(1)	(1)
Funded (Underfunded) Status	15	10
Pension Plans | SOUTHWESTERN ELECTRIC POWER COMPANY
Defined Benefit Plan Disclosure [Line Items]
Other Noncurrent Assets - Employee Benefits and Pension Assets	0	0
Other Current Liabilities – Accrued Short-term Benefit Liability	0	0
Other Noncurrent Liabilities – Accrued Long-term Benefit Liability	(33)	(39)
Funded (Underfunded) Status	(33)	(39)
OPEB
Defined Benefit Plan Disclosure [Line Items]
Other Noncurrent Assets - Employee Benefits and Pension Assets	1,404	1,130
Other Current Liabilities – Accrued Short-term Benefit Liability	(2)	(2)
Other Noncurrent Liabilities – Accrued Long-term Benefit Liability	2	1
Funded (Underfunded) Status	1,404	1,129
OPEB | AEP TEXAS INC.
Defined Benefit Plan Disclosure [Line Items]
Other Noncurrent Assets - Employee Benefits and Pension Assets	122	97
Other Current Liabilities – Accrued Short-term Benefit Liability	0	0
Other Noncurrent Liabilities – Accrued Long-term Benefit Liability	0	0
Funded (Underfunded) Status	122	97
OPEB | APPALACHIAN POWER COMPANY
Defined Benefit Plan Disclosure [Line Items]
Other Noncurrent Assets - Employee Benefits and Pension Assets	208	168
Other Current Liabilities – Accrued Short-term Benefit Liability	(1)	(1)
Other Noncurrent Liabilities – Accrued Long-term Benefit Liability	(11)	(13)
Funded (Underfunded) Status	196	154
OPEB | INDIANA MICHIGAN POWER COMPANY
Defined Benefit Plan Disclosure [Line Items]
Other Noncurrent Assets - Employee Benefits and Pension Assets	172	139
Other Current Liabilities – Accrued Short-term Benefit Liability	0	0
Other Noncurrent Liabilities – Accrued Long-term Benefit Liability	0	0
Funded (Underfunded) Status	172	139
OPEB | OHIO POWER COMPANY
Defined Benefit Plan Disclosure [Line Items]
Other Noncurrent Assets - Employee Benefits and Pension Assets	147	122
Other Current Liabilities – Accrued Short-term Benefit Liability	0	0
Other Noncurrent Liabilities – Accrued Long-term Benefit Liability	0	0
Funded (Underfunded) Status	147	122
OPEB | PUBLIC SERVICE COMPANY OF OKLAHOMA
Defined Benefit Plan Disclosure [Line Items]
Other Noncurrent Assets - Employee Benefits and Pension Assets	79	62
Other Current Liabilities – Accrued Short-term Benefit Liability	0	0
Other Noncurrent Liabilities – Accrued Long-term Benefit Liability	0	0
Funded (Underfunded) Status	79	62
OPEB | SOUTHWESTERN ELECTRIC POWER COMPANY
Defined Benefit Plan Disclosure [Line Items]
Other Noncurrent Assets - Employee Benefits and Pension Assets	101	80
Other Current Liabilities – Accrued Short-term Benefit Liability	0	0
Other Noncurrent Liabilities – Accrued Long-term Benefit Liability	0	0
Funded (Underfunded) Status	$ 101	$ 80