DERIVATIVES AND HEDGING - Schedule of the Notional Volume of Derivative Instruments (Details) gal in Millions, MWh in Millions, MMBTU in Millions, $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2025 USD ($) MWh MMBTU gal	Dec. 31, 2024 USD ($) MWh MMBTU gal
Power (MWhs)
Derivative [Line Items]
Notional amount, energy measure | MWh	327.3	282.4
Power (MWhs) | AEP Texas
Derivative [Line Items]
Notional amount, energy measure | MWh	0.0	0.0
Power (MWhs) | APCo
Derivative [Line Items]
Notional amount, energy measure | MWh	37.9	23.6
Power (MWhs) | I&M
Derivative [Line Items]
Notional amount, energy measure | MWh	11.7	7.7
Power (MWhs) | OPCo
Derivative [Line Items]
Notional amount, energy measure | MWh	1.8	2.0
Power (MWhs) | PSO
Derivative [Line Items]
Notional amount, energy measure | MWh	11.3	5.0
Power (MWhs) | SWEPCo
Derivative [Line Items]
Notional amount, energy measure | MWh	9.4	4.6
Natural Gas (MMBtus)
Derivative [Line Items]
Notional amount, energy measure | MMBTU	168.5	152.8
Natural Gas (MMBtus) | AEP Texas
Derivative [Line Items]
Notional amount, energy measure | MMBTU	0.0	0.0
Natural Gas (MMBtus) | APCo
Derivative [Line Items]
Notional amount, energy measure | MMBTU	46.8	42.2
Natural Gas (MMBtus) | I&M
Derivative [Line Items]
Notional amount, energy measure | MMBTU	0.0	0.0
Natural Gas (MMBtus) | OPCo
Derivative [Line Items]
Notional amount, energy measure | MMBTU	0.0	0.0
Natural Gas (MMBtus) | PSO
Derivative [Line Items]
Notional amount, energy measure | MMBTU	42.0	46.2
Natural Gas (MMBtus) | SWEPCo
Derivative [Line Items]
Notional amount, energy measure | MMBTU	19.2	15.4
Heating Oil and Gasoline (Gallons)
Derivative [Line Items]
Notional amount, volume | gal	7.5	7.9
Heating Oil and Gasoline (Gallons) | AEP Texas
Derivative [Line Items]
Notional amount, volume | gal	2.1	2.0
Heating Oil and Gasoline (Gallons) | APCo
Derivative [Line Items]
Notional amount, volume | gal	0.9	0.9
Heating Oil and Gasoline (Gallons) | I&M
Derivative [Line Items]
Notional amount, volume | gal	1.4	2.0
Heating Oil and Gasoline (Gallons) | OPCo
Derivative [Line Items]
Notional amount, volume | gal	1.1	1.1
Heating Oil and Gasoline (Gallons) | PSO
Derivative [Line Items]
Notional amount, volume | gal	0.7	0.7
Heating Oil and Gasoline (Gallons) | SWEPCo
Derivative [Line Items]
Notional amount, volume | gal	0.9	0.9
Interest Rate (USD)
Derivative [Line Items]
Derivative, notional amount	$ 39.5	$ 59.3
Interest Rate (USD) | AEP Texas
Derivative [Line Items]
Derivative, notional amount	0.0	0.0
Interest Rate (USD) | APCo
Derivative [Line Items]
Derivative, notional amount	0.0	0.0
Interest Rate (USD) | I&M
Derivative [Line Items]
Derivative, notional amount	0.0	0.0
Interest Rate (USD) | OPCo
Derivative [Line Items]
Derivative, notional amount	0.0	0.0
Interest Rate (USD) | PSO
Derivative [Line Items]
Derivative, notional amount	0.0	0.0
Interest Rate (USD) | SWEPCo
Derivative [Line Items]
Derivative, notional amount	0.0	0.0
Interest Rate
Derivative [Line Items]
Derivative, notional amount	950.0	950.0
Interest Rate | AEP Texas
Derivative [Line Items]
Derivative, notional amount	0.0	0.0
Interest Rate | APCo
Derivative [Line Items]
Derivative, notional amount	0.0	0.0
Interest Rate | I&M
Derivative [Line Items]
Derivative, notional amount	0.0	0.0
Interest Rate | OPCo
Derivative [Line Items]
Derivative, notional amount	0.0	0.0
Interest Rate | PSO
Derivative [Line Items]
Derivative, notional amount	0.0	0.0
Interest Rate | SWEPCo
Derivative [Line Items]
Derivative, notional amount	$ 0.0	$ 0.0