v3.26.1
Acquisitions - Additional Information (Details) - USD ($)
$ in Millions
 3 Months Ended 6 Months Ended 9 Months Ended
Mar. 31, 2026
Jun. 30, 2026
Jun. 30, 2025
Mar. 31, 2026
Jun. 30, 2026
Jun. 30, 2025
Sep. 30, 2025
Business Combination [Line Items]              
Goodwill   $ 1,895.2 $ 1,171.6   $ 1,895.2 $ 1,171.6 $ 1,171.6
Net Income (Loss)   211.2 $ 20.9   588.4 $ 311.5  
Piedmont Tennessee Transaction [Member]              
Business Combination [Line Items]              
Consideration transferred in cash $ 2,500.0     $ 2,500.0      
Goodwill purchase accounting for the acquisition   3.8          
Goodwill $ 741.7 741.7   $ 741.7 741.7    
Natural gas distribution business contributed revenues   44.8          
Net Income (Loss)   (6.9)          
Location, Statement of Income, Balance [Axis]: us-gaap:UtilitiesOperatingExpenseMaintenanceOperationsAndOtherCostsAndExpenses              
Business Combination [Line Items]              
Transaction costs incurred in association with acquisition   $ 1.4     $ 26.4