DERIVATIVES AND HEDGING - Schedule of the Notional Volume of Derivative Instruments (Details) gal in Millions, MWh in Millions, MMBTU in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2025 USD ($) MWh MMBTU gal	Dec. 31, 2024 USD ($) MWh MMBTU gal
Power (MWhs)
Derivative [Line Items]
Notional amount, energy measure | MWh	327	282
Power (MWhs) | AEP Texas
Derivative [Line Items]
Notional amount, energy measure | MWh	0	0
Power (MWhs) | APCo
Derivative [Line Items]
Notional amount, energy measure | MWh	23	24
Power (MWhs) | I&M
Derivative [Line Items]
Notional amount, energy measure | MWh	8	8
Power (MWhs) | OPCo
Derivative [Line Items]
Notional amount, energy measure | MWh	2	2
Power (MWhs) | PSO
Derivative [Line Items]
Notional amount, energy measure | MWh	8	5
Power (MWhs) | SWEPCo
Derivative [Line Items]
Notional amount, energy measure | MWh	6	5
Natural Gas (MMBtus)
Derivative [Line Items]
Notional amount, energy measure | MMBTU	166	153
Natural Gas (MMBtus) | AEP Texas
Derivative [Line Items]
Notional amount, energy measure | MMBTU	0	0
Natural Gas (MMBtus) | APCo
Derivative [Line Items]
Notional amount, energy measure | MMBTU	48	42
Natural Gas (MMBtus) | I&M
Derivative [Line Items]
Notional amount, energy measure | MMBTU	0	0
Natural Gas (MMBtus) | OPCo
Derivative [Line Items]
Notional amount, energy measure | MMBTU	0	0
Natural Gas (MMBtus) | PSO
Derivative [Line Items]
Notional amount, energy measure | MMBTU	44	46
Natural Gas (MMBtus) | SWEPCo
Derivative [Line Items]
Notional amount, energy measure | MMBTU	26	15
Heating Oil and Gasoline (Gallons)
Derivative [Line Items]
Notional amount, volume | gal	8	8
Heating Oil and Gasoline (Gallons) | AEP Texas
Derivative [Line Items]
Notional amount, volume | gal	2	2
Heating Oil and Gasoline (Gallons) | APCo
Derivative [Line Items]
Notional amount, volume | gal	1	1
Heating Oil and Gasoline (Gallons) | I&M
Derivative [Line Items]
Notional amount, volume | gal	2	2
Heating Oil and Gasoline (Gallons) | OPCo
Derivative [Line Items]
Notional amount, volume | gal	1	1
Heating Oil and Gasoline (Gallons) | PSO
Derivative [Line Items]
Notional amount, volume | gal	1	1
Heating Oil and Gasoline (Gallons) | SWEPCo
Derivative [Line Items]
Notional amount, volume | gal	1	1
Interest Rate (USD)
Derivative [Line Items]
Notional amount	$ 40	$ 59
Interest Rate (USD) | AEP Texas
Derivative [Line Items]
Notional amount	0	0
Interest Rate (USD) | APCo
Derivative [Line Items]
Notional amount	0	0
Interest Rate (USD) | I&M
Derivative [Line Items]
Notional amount	0	0
Interest Rate (USD) | OPCo
Derivative [Line Items]
Notional amount	0	0
Interest Rate (USD) | PSO
Derivative [Line Items]
Notional amount	0	0
Interest Rate (USD) | SWEPCo
Derivative [Line Items]
Notional amount	0	0
Interest Rate on Long-term Debt (USD)
Derivative [Line Items]
Notional amount	500	950
Interest Rate on Long-term Debt (USD) | AEP Texas
Derivative [Line Items]
Notional amount	0	0
Interest Rate on Long-term Debt (USD) | APCo
Derivative [Line Items]
Notional amount	0	0
Interest Rate on Long-term Debt (USD) | I&M
Derivative [Line Items]
Notional amount	0	0
Interest Rate on Long-term Debt (USD) | OPCo
Derivative [Line Items]
Notional amount	0	0
Interest Rate on Long-term Debt (USD) | PSO
Derivative [Line Items]
Notional amount	0	0
Interest Rate on Long-term Debt (USD) | SWEPCo
Derivative [Line Items]
Notional amount	$ 0	$ 0