BENEFIT PLANS - Schedule of Estimated Future Benefit Payments and Contributions (Details) $ in Millions	Dec. 31, 2025 USD ($)
Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Expected contributions and payments during the next fiscal year	$ 83
Pension Plans | AEP TEXAS INC.
Defined Benefit Plan Disclosure [Line Items]
Expected contributions and payments during the next fiscal year	11
Pension Plans | APPALACHIAN POWER COMPANY
Defined Benefit Plan Disclosure [Line Items]
Expected contributions and payments during the next fiscal year	0
Pension Plans | INDIANA MICHIGAN POWER COMPANY
Defined Benefit Plan Disclosure [Line Items]
Expected contributions and payments during the next fiscal year	1
Pension Plans | OHIO POWER COMPANY
Defined Benefit Plan Disclosure [Line Items]
Expected contributions and payments during the next fiscal year	0
Pension Plans | PUBLIC SERVICE COMPANY OF OKLAHOMA
Defined Benefit Plan Disclosure [Line Items]
Expected contributions and payments during the next fiscal year	0
Pension Plans | SOUTHWESTERN ELECTRIC POWER COMPANY
Defined Benefit Plan Disclosure [Line Items]
Expected contributions and payments during the next fiscal year	8
OPEB
Defined Benefit Plan Disclosure [Line Items]
Expected contributions and payments during the next fiscal year	2
OPEB | AEP TEXAS INC.
Defined Benefit Plan Disclosure [Line Items]
Expected contributions and payments during the next fiscal year	0
OPEB | APPALACHIAN POWER COMPANY
Defined Benefit Plan Disclosure [Line Items]
Expected contributions and payments during the next fiscal year	1
OPEB | INDIANA MICHIGAN POWER COMPANY
Defined Benefit Plan Disclosure [Line Items]
Expected contributions and payments during the next fiscal year	0
OPEB | OHIO POWER COMPANY
Defined Benefit Plan Disclosure [Line Items]
Expected contributions and payments during the next fiscal year	0
OPEB | PUBLIC SERVICE COMPANY OF OKLAHOMA
Defined Benefit Plan Disclosure [Line Items]
Expected contributions and payments during the next fiscal year	0
OPEB | SOUTHWESTERN ELECTRIC POWER COMPANY
Defined Benefit Plan Disclosure [Line Items]
Expected contributions and payments during the next fiscal year	$ 0