v3.26.1
Pending Acquisition (Details) - USD ($)
$ / shares in Units, $ in Thousands
 9 Months Ended
Oct. 01, 2026
Dec. 17, 2025
Nov. 06, 2025
Jun. 30, 2026
Jun. 30, 2025
Jun. 10, 2026
Sep. 30, 2025
Business Combination [Line Items]              
Common stock, par value (in dollars per share)       $ 1     $ 1
Net Proceeds from Common Stock Sale       $ 338,396 $ 0    
Net Proceeds from Issuance of Long-Term Debt       1,481,195 $ 988,731    
4.75%, 5.05% & 5.50% Notes Issued June 2026              
Business Combination [Line Items]              
Amount of issuance           $ 1,500,000  
Net Proceeds from Issuance of Long-Term Debt       $ 1,481,200      
Sale of Common Stock              
Business Combination [Line Items]              
Common stock issued from sale of common stock (in shares)   4,402,513   4,402,513      
Common stock, par value (in dollars per share)   $ 1.00          
Per share or per unit amount of equity securities issued (in dollars per share)   $ 79.50          
Net Proceeds from Common Stock Sale       $ 338,400      
Vectren Energy Delivery of Ohio, LLC | Senior Unsecured Bridge Loan Facility & Term Loan Facility Commitment Letter, Net              
Business Combination [Line Items]              
Total commitments under loan facilities       $ 1,100,000      
Vectren Energy Delivery of Ohio, LLC | Term Loan Facility, Commitment Letter              
Business Combination [Line Items]              
Debt instrument, term     364 days        
Forecast | Vectren Energy Delivery of Ohio, LLC              
Business Combination [Line Items]              
Total consideration $ 2,620,000            
Payments to acquire businesses, gross 1,420,000            
Forecast | Vectren Energy Delivery of Ohio, LLC | Promissory Note              
Business Combination [Line Items]              
Promissory note, face amount $ 1,200,000            
Debt instrument, term 364 days            
Interest rate (in percent) 6.50%