COMMITMENTS, GUARANTEES AND CONTINGENCIES - Potential Loss on Master Lease Agreements (Details) $ in Millions	Sep. 30, 2025 USD ($)
Other Commitments [Line Items]
Maximum Potential Loss	$ 37.9
AEP Texas
Other Commitments [Line Items]
Maximum Potential Loss	8.4
APCo
Other Commitments [Line Items]
Maximum Potential Loss	5.3
I&M
Other Commitments [Line Items]
Maximum Potential Loss	3.9
OPCo
Other Commitments [Line Items]
Maximum Potential Loss	6.4
PSO
Other Commitments [Line Items]
Maximum Potential Loss	3.5
SWEPCo
Other Commitments [Line Items]
Maximum Potential Loss	$ 4.4