COMMITMENTS, GUARANTEES AND CONTINGENCIES - Potential Loss on Master Lease Agreements (Details) $ in Millions	Mar. 31, 2026 USD ($)
Other Commitments [Line Items]
Maximum Potential Loss	$ 36
AEP Texas
Other Commitments [Line Items]
Maximum Potential Loss	8
APPALACHIAN POWER COMPANY
Other Commitments [Line Items]
Maximum Potential Loss	5
I&M
Other Commitments [Line Items]
Maximum Potential Loss	4
OPCo
Other Commitments [Line Items]
Maximum Potential Loss	6
PSO
Other Commitments [Line Items]
Maximum Potential Loss	3
SWEPCo
Other Commitments [Line Items]
Maximum Potential Loss	$ 4