DERIVATIVES AND HEDGING - Schedule of Gain (Loss) Recognized on Risk Management Contracts (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2026	Sep. 30, 2025	Sep. 30, 2026	Sep. 30, 2025
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Total Gain (Loss) on Risk Management Contracts	$ 227	$ 73	$ 675	$ 336
Location, Statement of Financial Position, Activity, Accrual [Axis]: us-gaap:RegulatoryAssetsNoncurrent
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Total Gain (Loss) on Risk Management Contracts	13	(4)	15	(9)
Location, Statement of Financial Position, Activity, Accrual [Axis]: us-gaap:RegulatoryLiabilityNoncurrent
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Total Gain (Loss) on Risk Management Contracts	155	59	503	283
AEP Texas
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Total Gain (Loss) on Risk Management Contracts	2	0	4	0
AEP Texas \| Location, Statement of Financial Position, Activity, Accrual [Axis]: us-gaap:RegulatoryAssetsNoncurrent
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Total Gain (Loss) on Risk Management Contracts	0	0	0	0
AEP Texas \| Location, Statement of Financial Position, Activity, Accrual [Axis]: us-gaap:RegulatoryLiabilityNoncurrent
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Total Gain (Loss) on Risk Management Contracts	1	0	2	0
APCo
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Total Gain (Loss) on Risk Management Contracts	70	19	243	83
APCo \| Location, Statement of Financial Position, Activity, Accrual [Axis]: us-gaap:RegulatoryAssetsNoncurrent
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Total Gain (Loss) on Risk Management Contracts	0	0	0	0
APCo \| Location, Statement of Financial Position, Activity, Accrual [Axis]: us-gaap:RegulatoryLiabilityNoncurrent
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Total Gain (Loss) on Risk Management Contracts	62	18	220	78
I&M
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Total Gain (Loss) on Risk Management Contracts	2	14	(14)	7
I&M \| Location, Statement of Financial Position, Activity, Accrual [Axis]: us-gaap:RegulatoryAssetsNoncurrent
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Total Gain (Loss) on Risk Management Contracts	0	1	0	0
I&M \| Location, Statement of Financial Position, Activity, Accrual [Axis]: us-gaap:RegulatoryLiabilityNoncurrent
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Total Gain (Loss) on Risk Management Contracts	13	7	27	22
OPCo
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Total Gain (Loss) on Risk Management Contracts	9	4	18	4
OPCo \| Location, Statement of Financial Position, Activity, Accrual [Axis]: us-gaap:RegulatoryAssetsNoncurrent
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Total Gain (Loss) on Risk Management Contracts	7	3	12	3
OPCo \| Location, Statement of Financial Position, Activity, Accrual [Axis]: us-gaap:RegulatoryLiabilityNoncurrent
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Total Gain (Loss) on Risk Management Contracts	2	1	5	1
PSO
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Total Gain (Loss) on Risk Management Contracts	22	5	97	70
PSO \| Location, Statement of Financial Position, Activity, Accrual [Axis]: us-gaap:RegulatoryAssetsNoncurrent
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Total Gain (Loss) on Risk Management Contracts	(4)	(12)	(3)	(14)
PSO \| Location, Statement of Financial Position, Activity, Accrual [Axis]: us-gaap:RegulatoryLiabilityNoncurrent
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Total Gain (Loss) on Risk Management Contracts	25	17	99	84
SWEPCo
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Total Gain (Loss) on Risk Management Contracts	45	15	97	84
SWEPCo \| Location, Statement of Financial Position, Activity, Accrual [Axis]: us-gaap:RegulatoryAssetsNoncurrent
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Total Gain (Loss) on Risk Management Contracts	10	3	6	1
SWEPCo \| Location, Statement of Financial Position, Activity, Accrual [Axis]: us-gaap:RegulatoryLiabilityNoncurrent
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Total Gain (Loss) on Risk Management Contracts	34	12	90	83
Location, Statement of Income, Balance [Axis]: us-gaap:UtilitiesOperatingExpenseMaintenance
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Total Gain (Loss) on Risk Management Contracts	2		4
Location, Statement of Income, Balance [Axis]: us-gaap:UtilitiesOperatingExpenseMaintenance \| AEP Texas
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Total Gain (Loss) on Risk Management Contracts	0		1
Location, Statement of Income, Balance [Axis]: us-gaap:UtilitiesOperatingExpenseMaintenance \| APCo
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Total Gain (Loss) on Risk Management Contracts	0		1
Location, Statement of Income, Balance [Axis]: us-gaap:UtilitiesOperatingExpenseMaintenance \| I&M
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Total Gain (Loss) on Risk Management Contracts	0		0
Location, Statement of Income, Balance [Axis]: us-gaap:UtilitiesOperatingExpenseMaintenance \| OPCo
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Total Gain (Loss) on Risk Management Contracts	0		1
Location, Statement of Income, Balance [Axis]: us-gaap:UtilitiesOperatingExpenseMaintenance \| PSO
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Total Gain (Loss) on Risk Management Contracts	1		1
Location, Statement of Income, Balance [Axis]: us-gaap:UtilitiesOperatingExpenseMaintenance \| SWEPCo
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Total Gain (Loss) on Risk Management Contracts	1		1
Location, Statement of Income, Balance [Axis]: us-gaap:UtilitiesOperatingExpenseOperations
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Total Gain (Loss) on Risk Management Contracts	1		3
Location, Statement of Income, Balance [Axis]: us-gaap:UtilitiesOperatingExpenseOperations \| AEP Texas
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Total Gain (Loss) on Risk Management Contracts	1		1
Location, Statement of Income, Balance [Axis]: us-gaap:UtilitiesOperatingExpenseOperations \| APCo
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Total Gain (Loss) on Risk Management Contracts	0		0
Location, Statement of Income, Balance [Axis]: us-gaap:UtilitiesOperatingExpenseOperations \| I&M
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Total Gain (Loss) on Risk Management Contracts	0		0
Location, Statement of Income, Balance [Axis]: us-gaap:UtilitiesOperatingExpenseOperations \| OPCo
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Total Gain (Loss) on Risk Management Contracts	0		0
Location, Statement of Income, Balance [Axis]: us-gaap:UtilitiesOperatingExpenseOperations \| PSO
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Total Gain (Loss) on Risk Management Contracts	0		0
Location, Statement of Income, Balance [Axis]: us-gaap:UtilitiesOperatingExpenseOperations \| SWEPCo
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Total Gain (Loss) on Risk Management Contracts	0		0
Vertically Integrated Utilities \| Location, Statement of Income, Balance [Axis]: us-gaap:Revenues
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Total Gain (Loss) on Risk Management Contracts	(10)	6	(39)	(14)
Vertically Integrated Utilities \| Location, Statement of Income, Balance [Axis]: us-gaap:Revenues \| AEP Texas
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Total Gain (Loss) on Risk Management Contracts	0	0	0	0
Vertically Integrated Utilities \| Location, Statement of Income, Balance [Axis]: us-gaap:Revenues \| APCo
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Total Gain (Loss) on Risk Management Contracts	0	0	0	0
Vertically Integrated Utilities \| Location, Statement of Income, Balance [Axis]: us-gaap:Revenues \| I&M
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Total Gain (Loss) on Risk Management Contracts	0	0	0	0
Vertically Integrated Utilities \| Location, Statement of Income, Balance [Axis]: us-gaap:Revenues \| OPCo
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Total Gain (Loss) on Risk Management Contracts	0	0	0	0
Vertically Integrated Utilities \| Location, Statement of Income, Balance [Axis]: us-gaap:Revenues \| PSO
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Total Gain (Loss) on Risk Management Contracts	0	0	0	0
Vertically Integrated Utilities \| Location, Statement of Income, Balance [Axis]: us-gaap:Revenues \| SWEPCo
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Total Gain (Loss) on Risk Management Contracts	0	0	0	0
Generation & Marketing Revenues \| Location, Statement of Income, Balance [Axis]: us-gaap:Revenues
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Total Gain (Loss) on Risk Management Contracts	59	11	169	71
Generation & Marketing Revenues \| Location, Statement of Income, Balance [Axis]: us-gaap:Revenues \| AEP Texas
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Total Gain (Loss) on Risk Management Contracts	0	0	0	0
Generation & Marketing Revenues \| Location, Statement of Income, Balance [Axis]: us-gaap:Revenues \| APCo
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Total Gain (Loss) on Risk Management Contracts	0	0	0	0
Generation & Marketing Revenues \| Location, Statement of Income, Balance [Axis]: us-gaap:Revenues \| I&M
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Total Gain (Loss) on Risk Management Contracts	0	0	0	0
Generation & Marketing Revenues \| Location, Statement of Income, Balance [Axis]: us-gaap:Revenues \| OPCo
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Total Gain (Loss) on Risk Management Contracts	0	0	0	0
Generation & Marketing Revenues \| Location, Statement of Income, Balance [Axis]: us-gaap:Revenues \| PSO
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Total Gain (Loss) on Risk Management Contracts	0	0	0	0
Generation & Marketing Revenues \| Location, Statement of Income, Balance [Axis]: us-gaap:Revenues \| SWEPCo
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Total Gain (Loss) on Risk Management Contracts	0	0	0	0
Electric Generation, Transmission and Distribution \| Location, Statement of Income, Balance [Axis]: us-gaap:Revenues
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Total Gain (Loss) on Risk Management Contracts	0	0	0	0
Electric Generation, Transmission and Distribution \| Location, Statement of Income, Balance [Axis]: us-gaap:Revenues \| AEP Texas
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Total Gain (Loss) on Risk Management Contracts	0	0	0	0
Electric Generation, Transmission and Distribution \| Location, Statement of Income, Balance [Axis]: us-gaap:Revenues \| APCo
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Total Gain (Loss) on Risk Management Contracts	1	0	2	0
Electric Generation, Transmission and Distribution \| Location, Statement of Income, Balance [Axis]: us-gaap:Revenues \| I&M
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Total Gain (Loss) on Risk Management Contracts	(11)	6	(41)	(15)
Electric Generation, Transmission and Distribution \| Location, Statement of Income, Balance [Axis]: us-gaap:Revenues \| OPCo
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Total Gain (Loss) on Risk Management Contracts	0	0	0	0
Electric Generation, Transmission and Distribution \| Location, Statement of Income, Balance [Axis]: us-gaap:Revenues \| PSO
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Total Gain (Loss) on Risk Management Contracts	0	0	0	0
Electric Generation, Transmission and Distribution \| Location, Statement of Income, Balance [Axis]: us-gaap:Revenues \| SWEPCo
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Total Gain (Loss) on Risk Management Contracts	0	0	0	0
Purchased Electricity, Fuel and Other Consumables Used for Electric Generation \| Location, Statement of Income, Balance [Axis]: us-gaap:CostOfGoodsAndServiceExcludingDepreciationDepletionAndAmortization
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Total Gain (Loss) on Risk Management Contracts	7	1	20	5
Purchased Electricity, Fuel and Other Consumables Used for Electric Generation \| Location, Statement of Income, Balance [Axis]: us-gaap:CostOfGoodsAndServiceExcludingDepreciationDepletionAndAmortization \| AEP Texas
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Total Gain (Loss) on Risk Management Contracts	0	0	0	0
Purchased Electricity, Fuel and Other Consumables Used for Electric Generation \| Location, Statement of Income, Balance [Axis]: us-gaap:CostOfGoodsAndServiceExcludingDepreciationDepletionAndAmortization \| APCo
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Total Gain (Loss) on Risk Management Contracts	7	1	20	5
Purchased Electricity, Fuel and Other Consumables Used for Electric Generation \| Location, Statement of Income, Balance [Axis]: us-gaap:CostOfGoodsAndServiceExcludingDepreciationDepletionAndAmortization \| I&M
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Total Gain (Loss) on Risk Management Contracts	0	0	0	0
Purchased Electricity, Fuel and Other Consumables Used for Electric Generation \| Location, Statement of Income, Balance [Axis]: us-gaap:CostOfGoodsAndServiceExcludingDepreciationDepletionAndAmortization \| OPCo
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Total Gain (Loss) on Risk Management Contracts	0	0	0	0
Purchased Electricity, Fuel and Other Consumables Used for Electric Generation \| Location, Statement of Income, Balance [Axis]: us-gaap:CostOfGoodsAndServiceExcludingDepreciationDepletionAndAmortization \| PSO
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Total Gain (Loss) on Risk Management Contracts	0	0	0	0
Purchased Electricity, Fuel and Other Consumables Used for Electric Generation \| Location, Statement of Income, Balance [Axis]: us-gaap:CostOfGoodsAndServiceExcludingDepreciationDepletionAndAmortization \| SWEPCo
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Total Gain (Loss) on Risk Management Contracts	$ 0	$ 0	$ 0	$ 0