v3.26.3
ACQUISITIONS, DISPOSITIONS AND IMPAIRMENTS - Impact of Asset Acquisitions (Details)
MW in Millions, $ in Millions
 1 Months Ended 12 Months Ended
Aug. 31, 2026
USD ($)
MW
May 31, 2026
USD ($)
MW
Mar. 31, 2026
USD ($)
MW
Dec. 31, 2025
USD ($)
MW
Sep. 30, 2026
USD ($)
Asset Acquisition, Contingent Consideration [Line Items]          
Property, Plant and Equipment, Net       $ 92,374 $ 100,228
Operating Lease Assets       661 660
Asset Retirement Obligations       3,556 3,669
Regulatory Liabilities and Deferred Investment Tax Credits       8,362 8,748
Other Current Liabilities       1,898 3,634
Deferred credits and other noncurrent liabilities       905 1,228
INDIANA MICHIGAN POWER COMPANY          
Asset Acquisition, Contingent Consideration [Line Items]          
Property, Plant and Equipment, Net       7,944 9,498
Operating Lease Assets       52 43
Asset Retirement Obligations       2,165 2,230
Regulatory Liabilities and Deferred Investment Tax Credits       2,938 3,346
Other Current Liabilities       230 228
Deferred credits and other noncurrent liabilities       89 50
PUBLIC SERVICE COMPANY OF OKLAHOMA          
Asset Acquisition, Contingent Consideration [Line Items]          
Property, Plant and Equipment, Net       8,964 10,436
Operating Lease Assets       126 140
Asset Retirement Obligations       136 165
Regulatory Liabilities and Deferred Investment Tax Credits       717 746
Other Current Liabilities       104 133
Deferred credits and other noncurrent liabilities       33 150
APPALACHIAN POWER COMPANY          
Asset Acquisition, Contingent Consideration [Line Items]          
Property, Plant and Equipment, Net       14,713 14,184
Operating Lease Assets       95 101
Asset Retirement Obligations       707 744
Regulatory Liabilities and Deferred Investment Tax Credits       1,111 1,092
Other Current Liabilities       271 370
Deferred credits and other noncurrent liabilities       $ 45 $ 40
Big Sandy Peaker Plant, LLC | INDIANA MICHIGAN POWER COMPANY          
Asset Acquisition, Contingent Consideration [Line Items]          
Net Maximum Capacity | MW 318        
Property, Plant and Equipment, Net $ 300        
Materials and Supplies 3        
Accounts Receivable 11        
Accounts Payable $ 4        
Lazbuddie Wind Energy, LLC | PUBLIC SERVICE COMPANY OF OKLAHOMA          
Asset Acquisition, Contingent Consideration [Line Items]          
Net Maximum Capacity | MW 265        
Property, Plant and Equipment, Net $ 637        
Operating Lease Assets 20        
Asset Retirement Obligations $ 8        
Wolf Hills Energy, LLC | AGR          
Asset Acquisition, Contingent Consideration [Line Items]          
Net Maximum Capacity | MW 263        
Property, Plant and Equipment, Net $ 85        
Materials and Supplies 2        
Accounts Receivable 7        
Accounts Payable $ 3        
Grover Hill Wind Project | APPALACHIAN POWER COMPANY          
Asset Acquisition, Contingent Consideration [Line Items]          
Net Maximum Capacity | MW   143      
Property, Plant and Equipment, Net   $ 361      
Operating Lease Assets   8      
Asset Retirement Obligations   $ 1      
Oregon Clean Energy Center | INDIANA MICHIGAN POWER COMPANY          
Asset Acquisition, Contingent Consideration [Line Items]          
Net Maximum Capacity | MW     870    
Property, Plant and Equipment, Net     $ 918    
Prepayments and Other Current Assets     35    
Materials and Supplies     5    
Accounts Receivable     16    
Accounts Payable     $ 9    
Four Electric Generation Facilities | PUBLIC SERVICE COMPANY OF OKLAHOMA          
Asset Acquisition, Contingent Consideration [Line Items]          
Net Maximum Capacity | MW       1,381  
Property, Plant and Equipment, Net       $ 1,842  
Operating Lease Assets       25  
Asset Retirement Obligations       19  
Other Liabilities       $ 91  
Green Country Energy, LLC | PUBLIC SERVICE COMPANY OF OKLAHOMA          
Asset Acquisition, Contingent Consideration [Line Items]          
Net Maximum Capacity | MW       904  
Property, Plant and Equipment, Net       $ 819  
Operating Lease Assets       0  
Asset Retirement Obligations       0  
Other Liabilities       91  
Regulatory Liabilities and Deferred Investment Tax Credits       50  
Other Current Liabilities       21  
Deferred credits and other noncurrent liabilities       $ 20  
Pixley Solar Energy, LLC | PUBLIC SERVICE COMPANY OF OKLAHOMA          
Asset Acquisition, Contingent Consideration [Line Items]          
Net Maximum Capacity | MW       189  
Property, Plant and Equipment, Net       $ 380  
Operating Lease Assets       9  
Asset Retirement Obligations       12  
Other Liabilities       $ 0  
Flat Ridge IV Wind, LLC | PUBLIC SERVICE COMPANY OF OKLAHOMA          
Asset Acquisition, Contingent Consideration [Line Items]          
Net Maximum Capacity | MW       135  
Property, Plant and Equipment, Net       $ 305  
Operating Lease Assets       7  
Asset Retirement Obligations       3  
Other Liabilities       $ 0  
Flat Ridge V Wind Energy, LLC | PUBLIC SERVICE COMPANY OF OKLAHOMA          
Asset Acquisition, Contingent Consideration [Line Items]          
Net Maximum Capacity | MW       153  
Property, Plant and Equipment, Net       $ 338  
Operating Lease Assets       9  
Asset Retirement Obligations       4  
Other Liabilities       $ 0