v3.26.3
DERIVATIVES AND HEDGING - Schedule of Offsetting Assets and Liabilities (Details) - USD ($)
$ in Millions
Sep. 30, 2026
Dec. 31, 2025
Total Assets    
Gross Amounts Recognized $ 2,233 $ 1,357
Current Risk Management Assets 588 352
Long-term Risk Management Assets 266 265
Total Risk Management Assets 854 617
Total Liabilities    
Gross Amounts Recognized 1,693 970
Current Risk Management Liabilities 209 132
Long-term Risk Management Liabilities 214 178
Total Risk Management Liabilities 423 310
Total MTM Derivative Contract Net Assets (Liabilities) 431 307
Location, Statement of Financial Position, Balance [Axis]: us-gaap:OtherLiabilitiesCurrent    
Total Liabilities    
Gross Amounts Recognized 1,123 532
Gross Amounts Offset (914) (400)
Location, Statement of Financial Position, Balance [Axis]: us-gaap:OtherLiabilitiesNoncurrent    
Total Liabilities    
Gross Amounts Recognized 570 438
Gross Amounts Offset (356) (260)
Location, Statement of Financial Position, Balance [Axis]: us-gaap:PrepaidExpenseAndOtherAssetsCurrent    
Total Assets    
Gross Amounts Recognized 1,549 776
Gross Amounts Offset (961) (424)
Location, Statement of Financial Position, Balance [Axis]: aep:DeferredChargesAndOtherNoncurrentAssets    
Total Assets    
Gross Amounts Recognized 684 581
Gross Amounts Offset (418) (316)
AEP Texas    
Total Assets    
Gross Amounts Recognized 2 0
Current Risk Management Assets 0 0
Long-term Risk Management Assets 0 0
Total Risk Management Assets 0 0
Total Liabilities    
Gross Amounts Recognized 0 0
Current Risk Management Liabilities 0 0
Long-term Risk Management Liabilities 0 0
Total Risk Management Liabilities 0 0
Total MTM Derivative Contract Net Assets (Liabilities) 0 0
AEP Texas | Location, Statement of Financial Position, Balance [Axis]: us-gaap:OtherLiabilitiesCurrent    
Total Liabilities    
Gross Amounts Recognized 0 0
Gross Amounts Offset 0 0
AEP Texas | Location, Statement of Financial Position, Balance [Axis]: us-gaap:OtherLiabilitiesNoncurrent    
Total Liabilities    
Gross Amounts Recognized 0 0
Gross Amounts Offset 0 0
AEP Texas | Location, Statement of Financial Position, Balance [Axis]: us-gaap:PrepaidExpenseAndOtherAssetsCurrent    
Total Assets    
Gross Amounts Recognized 2 0
Gross Amounts Offset (2) 0
AEP Texas | Location, Statement of Financial Position, Balance [Axis]: aep:DeferredChargesAndOtherNoncurrentAssets    
Total Assets    
Gross Amounts Recognized 0 0
Gross Amounts Offset 0 0
APCo    
Total Assets    
Gross Amounts Recognized 191 84
Current Risk Management Assets 188 81
Long-term Risk Management Assets 0 1
Total Risk Management Assets 188 82
Total Liabilities    
Gross Amounts Recognized 20 6
Current Risk Management Liabilities 18 3
Long-term Risk Management Liabilities 0 0
Total Risk Management Liabilities 18 3
Total MTM Derivative Contract Net Assets (Liabilities) 170 79
APCo | Location, Statement of Financial Position, Balance [Axis]: us-gaap:OtherLiabilitiesCurrent    
Total Liabilities    
Gross Amounts Recognized 19 5
Gross Amounts Offset (1) (2)
APCo | Location, Statement of Financial Position, Balance [Axis]: us-gaap:OtherLiabilitiesNoncurrent    
Total Liabilities    
Gross Amounts Recognized 1 1
Gross Amounts Offset (1) (1)
APCo | Location, Statement of Financial Position, Balance [Axis]: us-gaap:PrepaidExpenseAndOtherAssetsCurrent    
Total Assets    
Gross Amounts Recognized 190 82
Gross Amounts Offset (2) (1)
APCo | Location, Statement of Financial Position, Balance [Axis]: aep:DeferredChargesAndOtherNoncurrentAssets    
Total Assets    
Gross Amounts Recognized 1 2
Gross Amounts Offset (1) (1)
I&M    
Total Assets    
Gross Amounts Recognized 51 24
Current Risk Management Assets 26 10
Long-term Risk Management Assets 0 0
Total Risk Management Assets 26 10
Total Liabilities    
Gross Amounts Recognized 33 14
Current Risk Management Liabilities 1 0
Long-term Risk Management Liabilities 0 0
Total Risk Management Liabilities 1 0
Total MTM Derivative Contract Net Assets (Liabilities) 25 10
I&M | Location, Statement of Financial Position, Balance [Axis]: us-gaap:OtherLiabilitiesCurrent    
Total Liabilities    
Gross Amounts Recognized 33 13
Gross Amounts Offset (32) (13)
I&M | Location, Statement of Financial Position, Balance [Axis]: us-gaap:OtherLiabilitiesNoncurrent    
Total Liabilities    
Gross Amounts Recognized 0 1
Gross Amounts Offset 0 (1)
I&M | Location, Statement of Financial Position, Balance [Axis]: us-gaap:PrepaidExpenseAndOtherAssetsCurrent    
Total Assets    
Gross Amounts Recognized 51 23
Gross Amounts Offset (25) (13)
I&M | Location, Statement of Financial Position, Balance [Axis]: aep:DeferredChargesAndOtherNoncurrentAssets    
Total Assets    
Gross Amounts Recognized 0 1
Gross Amounts Offset 0 (1)
OPCo    
Total Assets    
Gross Amounts Recognized 1 0
Current Risk Management Assets 0 0
Long-term Risk Management Assets 0 0
Total Risk Management Assets 0 0
Total Liabilities    
Gross Amounts Recognized 22 33
Current Risk Management Liabilities 3 5
Long-term Risk Management Liabilities 19 28
Total Risk Management Liabilities 22 33
Total MTM Derivative Contract Net Assets (Liabilities) (22) (33)
OPCo | Location, Statement of Financial Position, Balance [Axis]: us-gaap:OtherLiabilitiesCurrent    
Total Liabilities    
Gross Amounts Recognized 3 5
Gross Amounts Offset 0 0
OPCo | Location, Statement of Financial Position, Balance [Axis]: us-gaap:OtherLiabilitiesNoncurrent    
Total Liabilities    
Gross Amounts Recognized 19 28
Gross Amounts Offset 0 0
OPCo | Location, Statement of Financial Position, Balance [Axis]: us-gaap:PrepaidExpenseAndOtherAssetsCurrent    
Total Assets    
Gross Amounts Recognized 1 0
Gross Amounts Offset (1) 0
OPCo | Location, Statement of Financial Position, Balance [Axis]: aep:DeferredChargesAndOtherNoncurrentAssets    
Total Assets    
Gross Amounts Recognized 0 0
Gross Amounts Offset 0 0
PSO    
Total Assets    
Gross Amounts Recognized 42 44
Current Risk Management Assets 41 42
Long-term Risk Management Assets 0 0
Total Risk Management Assets 41 42
Total Liabilities    
Gross Amounts Recognized 34 30
Current Risk Management Liabilities 29 27
Long-term Risk Management Liabilities 5 1
Total Risk Management Liabilities 34 28
Total MTM Derivative Contract Net Assets (Liabilities) 7 14
PSO | Location, Statement of Financial Position, Balance [Axis]: us-gaap:OtherLiabilitiesCurrent    
Total Liabilities    
Gross Amounts Recognized 29 29
Gross Amounts Offset 0 (2)
PSO | Location, Statement of Financial Position, Balance [Axis]: us-gaap:OtherLiabilitiesNoncurrent    
Total Liabilities    
Gross Amounts Recognized 5 1
Gross Amounts Offset 0 0
PSO | Location, Statement of Financial Position, Balance [Axis]: us-gaap:PrepaidExpenseAndOtherAssetsCurrent    
Total Assets    
Gross Amounts Recognized 42 44
Gross Amounts Offset (1) (2)
PSO | Location, Statement of Financial Position, Balance [Axis]: aep:DeferredChargesAndOtherNoncurrentAssets    
Total Assets    
Gross Amounts Recognized 0 0
Gross Amounts Offset 0 0
SWEPCo    
Total Assets    
Gross Amounts Recognized 44 37
Current Risk Management Assets 43 35
Long-term Risk Management Assets 0 0
Total Risk Management Assets 43 35
Total Liabilities    
Gross Amounts Recognized 12 13
Current Risk Management Liabilities 10 9
Long-term Risk Management Liabilities 2 2
Total Risk Management Liabilities 12 11
Total MTM Derivative Contract Net Assets (Liabilities) 31 24
SWEPCo | Location, Statement of Financial Position, Balance [Axis]: us-gaap:OtherLiabilitiesCurrent    
Total Liabilities    
Gross Amounts Recognized 10 11
Gross Amounts Offset 0 (2)
SWEPCo | Location, Statement of Financial Position, Balance [Axis]: us-gaap:OtherLiabilitiesNoncurrent    
Total Liabilities    
Gross Amounts Recognized 2 2
Gross Amounts Offset 0 0
SWEPCo | Location, Statement of Financial Position, Balance [Axis]: us-gaap:PrepaidExpenseAndOtherAssetsCurrent    
Total Assets    
Gross Amounts Recognized 44 37
Gross Amounts Offset (1) (2)
SWEPCo | Location, Statement of Financial Position, Balance [Axis]: aep:DeferredChargesAndOtherNoncurrentAssets    
Total Assets    
Gross Amounts Recognized 0 0
Gross Amounts Offset $ 0 $ 0