DERIVATIVES AND HEDGING - Schedule of Cash Flow Hedges Included in Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	6 Months Ended	12 Months Ended
Jun. 30, 2025	Dec. 31, 2024
Commodity
Derivative Instruments and Hedging Activities Disclosures [Line Items]
AOCI Gain (Loss) Net of Tax	$ 91.5	$ 98.5
Portion Expected to be Reclassed to Net Income During the Next Twelve Months	37.1	33.9
Commodity \| AEP Texas
Derivative Instruments and Hedging Activities Disclosures [Line Items]
AOCI Gain (Loss) Net of Tax	0.0	0.0
Portion Expected to be Reclassed to Net Income During the Next Twelve Months	0.0	0.0
Commodity \| APCo
Derivative Instruments and Hedging Activities Disclosures [Line Items]
AOCI Gain (Loss) Net of Tax	0.0	0.0
Portion Expected to be Reclassed to Net Income During the Next Twelve Months	0.0	0.0
Commodity \| I&M
Derivative Instruments and Hedging Activities Disclosures [Line Items]
AOCI Gain (Loss) Net of Tax	0.0	0.0
Portion Expected to be Reclassed to Net Income During the Next Twelve Months	0.0	0.0
Commodity \| PSO
Derivative Instruments and Hedging Activities Disclosures [Line Items]
AOCI Gain (Loss) Net of Tax	0.0	0.0
Portion Expected to be Reclassed to Net Income During the Next Twelve Months	0.0	0.0
Commodity \| SWEPCo
Derivative Instruments and Hedging Activities Disclosures [Line Items]
AOCI Gain (Loss) Net of Tax	0.0	0.0
Portion Expected to be Reclassed to Net Income During the Next Twelve Months	0.0	0.0
Interest Rate
Derivative Instruments and Hedging Activities Disclosures [Line Items]
AOCI Gain (Loss) Net of Tax	0.2	3.3
Portion Expected to be Reclassed to Net Income During the Next Twelve Months	0.8	2.8
Interest Rate \| AEP Texas
Derivative Instruments and Hedging Activities Disclosures [Line Items]
AOCI Gain (Loss) Net of Tax	5.9	6.3
Portion Expected to be Reclassed to Net Income During the Next Twelve Months	0.7	0.7
Interest Rate \| APCo
Derivative Instruments and Hedging Activities Disclosures [Line Items]
AOCI Gain (Loss) Net of Tax	4.7	5.1
Portion Expected to be Reclassed to Net Income During the Next Twelve Months	0.8	0.8
Interest Rate \| I&M
Derivative Instruments and Hedging Activities Disclosures [Line Items]
AOCI Gain (Loss) Net of Tax	(4.9)	(5.1)
Portion Expected to be Reclassed to Net Income During the Next Twelve Months	(0.4)	(0.4)
Interest Rate \| PSO
Derivative Instruments and Hedging Activities Disclosures [Line Items]
AOCI Gain (Loss) Net of Tax	2.4	3.6
Portion Expected to be Reclassed to Net Income During the Next Twelve Months	0.2	0.2
Interest Rate \| SWEPCo
Derivative Instruments and Hedging Activities Disclosures [Line Items]
AOCI Gain (Loss) Net of Tax	0.9	1.0
Portion Expected to be Reclassed to Net Income During the Next Twelve Months	$ 0.3	$ 0.3