v3.26.1
Overview and Summary of Significant Accounting Policies (Details)
$ in Thousands
3 Months Ended
Mar. 31, 2026
USD ($)
generating_station
MW
Mar. 31, 2025
USD ($)
Jan. 01, 2026
USD ($)
Dec. 31, 2025
USD ($)
Jan. 01, 2025
USD ($)
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]          
Income Tax Expense (Benefit) $ 34,222 $ 35,940      
Accumulated Other Comprehensive Income (Loss), Net of Tax 33,207     $ 33,641 $ 35,378
Inventories $ 16,727     21,694  
Number of customers 534,000        
Number of generating stations | generating_station 4        
Regulatory assets, current $ 50,834     52,089  
Inventory, Net 67,561     73,783  
Reclassification from AOCI, Current Period, Net of Tax, Attributable to Parent (434) (434)      
Capitalized Cost, Software to be Sold, Leased, or Marketed, Amortization Expense 7,665 7,669      
Business Combination, Achieved in Stages, Preacquisition Equity Interest in Acquiree, Remeasurement, Gain (Loss) (4) 5      
Allowance for Funds Used During Construction, Capitalized Interest 5,671 9,817      
Allowance for Funds Used During Construction, Equity Portion 1,590 669      
Capitalized Cost, Software to be Sold, Leased, or Marketed, before Accumulated Amortization 302,186     297,631  
Project development intangible assets 147,617     145,370  
Emissions Allowance 809     809  
Capitalized Cost, Software to be Sold, Leased, or Marketed, Accumulated Amortization (167,733)     (157,850)  
Intangible Asset, Including Goodwill, after Accumulated Amortization $ 282,879     285,960  
Petersburg Energy Center Project MW 250        
Petersburg Energy Storage Project MW 45        
Petersburg Energy Storage Project MwH 180        
Hardy Hills Solar Project MW 195        
Hoosier Wind Project MW 106        
Pike Co BESS Project MW 200        
Pike Co BESS Project MwH 800        
Liabilities $ 5,966,117     5,759,610  
Payments to Noncontrolling Interests (189,625) 0      
Investment Tax Credit   0      
Income Taxes Receivable 189,625     0  
Investment Tax Credit   0      
Accrued taxes 35,327     27,636  
Payments to Noncontrolling Interests $ (189,625) 0      
Crossvine Project | MW 85        
Crossvine Project Storage Capacity | MW 85        
Crossvine Project MwH | MW 340        
Asset Retirement Obligation [Line Items]          
Asset Retirement Obligation, Liabilities Incurred $ 0 250      
Asset Retirement Obligation, Liabilities Settled (3,405) (1,987)      
Asset Retirement Obligation, Revision of Estimate (4,589) (12,919)      
Asset Retirement Obligation, Accretion Expense 6,363 4,475      
Asset Retirement Obligation, Current 60,190 45,396   40,724  
Asset retirement obligations, non-current 511,366 322,883   532,463  
Asset Retirement Obligation $ 571,556 $ 368,279 $ 573,187   $ 378,460
Aes U.S. Investments [Member]          
Ownership percentage by parent (percent) 82.35%        
CDPQ [Member]          
Ownership percentage by parent (percent) 17.65%        
Ownership interest in parent company (percent) 15.00%        
AES U.S. Holdings, LLC [Member]          
Ownership interest in parent company (percent) 85.00%        
ITC          
Investment Tax Credit $ 189,600        
Investment Tax Credit $ 189,600        
Harding Street [Member]          
Amount of New Operation for Battery Storage Unit, megawatts | MW 20        
Variable Interest Entity, Primary Beneficiary          
Property, Plant, and Equipment, before Accumulated Depreciation, Depletion, and Amortization $ 1,695,600     1,488,700  
Liabilities $ 330,700     $ 276,400  
Subsidiaries [Member]          
Electric generation capability for winter, megawatts | MW 3,070        
Electric generation capability for summer, megawatts | MW 2,925