v3.26.3
Overview and Summary of Significant Accounting Policies (Details)
$ in Thousands
3 Months Ended 9 Months Ended
Sep. 30, 2026
USD ($)
customer
Sep. 30, 2025
USD ($)
Sep. 30, 2026
USD ($)
customer
Sep. 30, 2025
USD ($)
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) $ 40,098 $ 20,368 $ 87,189 $ 62,943      
Accumulated Other Comprehensive Income (Loss), Net of Tax 32,339   32,339     $ 33,641 $ 35,378
Inventories 3,070   3,070     21,694  
Regulatory assets, current 49,525   49,525     52,089  
Inventory, Net 52,595   52,595     73,783  
Reclassification from AOCI, Current Period, Net of Tax, Attributable to Parent (434) (434)   (1,302)      
Capitalized Cost, Software to be Sold, Leased, or Marketed, Amortization Expense 6,496 7,419 20,929 21,319      
Business Combination, Achieved in Stages, Preacquisition Equity Interest in Acquiree, Remeasurement, Gain (Loss) 0 0 19 164      
Allowance for Funds Used During Construction, Capitalized Interest 6,543 8,932 17,691 25,348      
Allowance for Funds Used During Construction, Equity Portion 2,204 622 5,648 2,023      
Capitalized Cost, Software to be Sold, Leased, or Marketed, before Accumulated Amortization 310,950   310,950     297,631  
Project development intangible assets 147,617   147,617     145,370  
Emissions Allowance 809   809     809  
Capitalized Cost, Software to be Sold, Leased, or Marketed, Accumulated Amortization (180,868)   (180,868)     (157,850)  
Intangible Asset, Including Goodwill, after Accumulated Amortization 278,508   278,508     285,960  
Liabilities 6,045,822   6,045,822     5,759,610  
Payments to Noncontrolling Interests     0 46,223      
Investment Tax Credit       133,010      
Investment Tax Credit       133,010      
Accrued taxes 40,397   40,397     27,636  
Payments to Noncontrolling Interests     0 46,223      
Asset Retirement Obligation [Line Items]              
Asset Retirement Obligation, Liabilities Incurred     1,539 1,515      
Asset Retirement Obligation, Liabilities Settled     (22,946) (17,314)      
Asset Retirement Obligation, Revision of Estimate     37,844 91,996      
Asset Retirement Obligation, Accretion Expense     19,225 12,876      
Asset Retirement Obligation, Current 58,850 44,537 58,850 44,537   40,724  
Asset retirement obligations, non-current 549,999 422,996 549,999 422,996   532,463  
Asset Retirement Obligation $ 608,849 $ 467,533 $ 608,849 467,533 $ 573,187   $ 378,460
Aes U.S. Investments [Member]              
Ownership percentage by parent (percent) 82.35%   82.35%        
CDPQ [Member]              
Ownership percentage by parent (percent) 17.65%   17.65%        
Ownership interest in parent company (percent) 15.00%   15.00%        
AES U.S. Holdings, LLC [Member]              
Ownership interest in parent company (percent) 85.00%   85.00%        
ITC              
Investment Tax Credit     $ 189,600 133,000      
Investment Tax Credit     189,600 133,000      
ITC | Installment Sale              
Investment Tax Credit       133,000      
Investment Tax Credit       $ 133,000      
Variable Interest Entity, Primary Beneficiary              
Property, Plant, and Equipment, before Accumulated Depreciation, Depletion, and Amortization $ 1,605,600   1,605,600     1,488,700  
Liabilities $ 157,000   $ 157,000     $ 276,400  
Subsidiaries [Member]              
Number of customers | customer 535,000   535,000