DERIVATIVES AND HEDGING - Schedule of Cash Flow Hedges Included in Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Commodity
Derivative Instruments and Hedging Activities Disclosures [Line Items]
AOCI Gain (Loss) Net of Tax	$ 78	$ 99
Portion Expected to be Reclassed to Net Income During the Next Twelve Months	31	34
Commodity | AEP Texas
Derivative Instruments and Hedging Activities Disclosures [Line Items]
AOCI Gain (Loss) Net of Tax	0	0
Portion Expected to be Reclassed to Net Income During the Next Twelve Months	0	0
Commodity | APCo
Derivative Instruments and Hedging Activities Disclosures [Line Items]
AOCI Gain (Loss) Net of Tax	0	0
Portion Expected to be Reclassed to Net Income During the Next Twelve Months	0	0
Commodity | I&M
Derivative Instruments and Hedging Activities Disclosures [Line Items]
AOCI Gain (Loss) Net of Tax	0	0
Portion Expected to be Reclassed to Net Income During the Next Twelve Months	0	0
Commodity | PSO
Derivative Instruments and Hedging Activities Disclosures [Line Items]
AOCI Gain (Loss) Net of Tax	0	0
Portion Expected to be Reclassed to Net Income During the Next Twelve Months	0	0
Commodity | SWEPCo
Derivative Instruments and Hedging Activities Disclosures [Line Items]
AOCI Gain (Loss) Net of Tax	0	0
Portion Expected to be Reclassed to Net Income During the Next Twelve Months	0	0
Interest Rate on Long-term Debt (USD)
Derivative Instruments and Hedging Activities Disclosures [Line Items]
AOCI Gain (Loss) Net of Tax	(1)	3
Portion Expected to be Reclassed to Net Income During the Next Twelve Months	0	3
Interest Rate on Long-term Debt (USD) | AEP Texas
Derivative Instruments and Hedging Activities Disclosures [Line Items]
AOCI Gain (Loss) Net of Tax	6	6
Portion Expected to be Reclassed to Net Income During the Next Twelve Months	1	1
Interest Rate on Long-term Debt (USD) | APCo
Derivative Instruments and Hedging Activities Disclosures [Line Items]
AOCI Gain (Loss) Net of Tax	4	5
Portion Expected to be Reclassed to Net Income During the Next Twelve Months	1	1
Interest Rate on Long-term Debt (USD) | I&M
Derivative Instruments and Hedging Activities Disclosures [Line Items]
AOCI Gain (Loss) Net of Tax	(5)	(5)
Portion Expected to be Reclassed to Net Income During the Next Twelve Months	0	0
Interest Rate on Long-term Debt (USD) | PSO
Derivative Instruments and Hedging Activities Disclosures [Line Items]
AOCI Gain (Loss) Net of Tax	2	4
Portion Expected to be Reclassed to Net Income During the Next Twelve Months	0	0
Interest Rate on Long-term Debt (USD) | SWEPCo
Derivative Instruments and Hedging Activities Disclosures [Line Items]
AOCI Gain (Loss) Net of Tax	1	1
Portion Expected to be Reclassed to Net Income During the Next Twelve Months	$ 0	$ 0