v3.26.1
COMMITMENTS, GUARANTEES AND CONTINGENCIES - Narrative (Details)
 3 Months Ended 6 Months Ended
Jun. 30, 2026
USD ($)
uncommittedFacility
a
unit
customer
Jun. 30, 2024
USD ($)
Jun. 30, 2026
USD ($)
uncommittedFacility
a
unit
Apr. 30, 2026
USD ($)
Mar. 31, 2026
USD ($)
Jan. 31, 2026
USD ($)
Other Commitments [Line Items]            
Number of uncommitted facilities | uncommittedFacility 7   7      
Liabilities Incurred     $ 3,000,000      
Area of land closed, noncompliant with CCR rule | a 300   300      
CCR Rule Revision            
Other Commitments [Line Items]            
Liabilities Incurred   $ 674,000,000        
Line of Credit | Revolving Credit Facility | Revolving Credit Facility, Due April 2031            
Other Commitments [Line Items]            
Line of credit facility, borrowing capacity       $ 6,500,000,000 $ 5,000,000,000  
Line of Credit | Revolving Credit Facility | Revolving Credit Facility, Due March 2027            
Other Commitments [Line Items]            
Line of credit facility, borrowing capacity         $ 1,000,000,000  
Line of Credit | Revolving Credit Facility | Revolving Credit Facility, Due April 2029            
Other Commitments [Line Items]            
Line of credit facility, borrowing capacity       $ 1,500,000,000    
Line of Credit | Letter of Credit            
Other Commitments [Line Items]            
Debt instrument, face amount $ 850,000,000   $ 850,000,000      
Long-term line of credit 131,000,000   131,000,000      
Letter of Credit | Revolving Credit Facility            
Other Commitments [Line Items]            
Letters of credit outstanding, amount 0   0      
Letter of Credit | Revolving Credit Facility | Subsidiaries            
Other Commitments [Line Items]            
Line of credit facility, borrowing capacity $ 1,200,000,000   $ 1,200,000,000      
OHIO POWER COMPANY | Ohio Valley Electric Corporation            
Other Commitments [Line Items]            
Ownership interest transferred to parent 4.30%   4.30%      
Power participation entitlement interest transferred to parent 19.93%   19.93%      
APPALACHIAN POWER COMPANY | CCR Rule Revision            
Other Commitments [Line Items]            
Asset retirement obligation, approved recovery amount           $ 80,000,000
INDIANA MICHIGAN POWER COMPANY | Cook Plant            
Other Commitments [Line Items]            
Nuclear contingencies, number of units | unit 2   2      
SOUTHWESTERN ELECTRIC POWER COMPANY            
Other Commitments [Line Items]            
Number of wholesale generation customers | customer 1          
Probable credit $ 23,000,000