INCOME TAXES - Tax Credit Carryforwards (Details) $ in Millions	Dec. 31, 2025 USD ($)
Federal
Effective Income Tax Rate Reconciliation [Line Items]
Tax credit carryforward	$ 108
Federal | AEP TEXAS INC.
Effective Income Tax Rate Reconciliation [Line Items]
Tax credit carryforward	10
Federal | APPALACHIAN POWER COMPANY
Effective Income Tax Rate Reconciliation [Line Items]
Tax credit carryforward	28
Federal | OHIO POWER COMPANY
Effective Income Tax Rate Reconciliation [Line Items]
Tax credit carryforward	43
Federal | PUBLIC SERVICE COMPANY OF OKLAHOMA
Effective Income Tax Rate Reconciliation [Line Items]
Tax credit carryforward	0
State and Local Government
Effective Income Tax Rate Reconciliation [Line Items]
Tax credit carryforward	41
State and Local Government | AEP TEXAS INC.
Effective Income Tax Rate Reconciliation [Line Items]
Tax credit carryforward	0
State and Local Government | APPALACHIAN POWER COMPANY
Effective Income Tax Rate Reconciliation [Line Items]
Tax credit carryforward	0
State and Local Government | OHIO POWER COMPANY
Effective Income Tax Rate Reconciliation [Line Items]
Tax credit carryforward	0
State and Local Government | PUBLIC SERVICE COMPANY OF OKLAHOMA
Effective Income Tax Rate Reconciliation [Line Items]
Tax credit carryforward	$ 41