v3.25.4
Revenue Recognition (Allowance for Credit Losses) (Details) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2025
Dec. 31, 2024
Dec. 31, 2023
Financing Receivable, Allowance for Credit Loss [Line Items]      
Allowance for Credit Loss $ 40.6 $ 23.7 $ 22.9
Current period provisions 67.3 38.8  
Write-offs charged against allowance (65.8) (55.7)  
Recoveries of amounts previously written off 15.4 17.7  
Accounts Receivable, Allowance for Credit Loss, Period Increase (Decrease) 16.5    
Electric Operations      
Financing Receivable, Allowance for Credit Loss [Line Items]      
Allowance for Credit Loss 25.0 13.9 11.9
Current period provisions 25.0 12.1  
Write-offs charged against allowance (15.0) (11.0)  
Recoveries of amounts previously written off 1.1 0.9  
Corporate Segment and Other Operating Segment      
Financing Receivable, Allowance for Credit Loss [Line Items]      
Allowance for Credit Loss 0.0 0.0 0.8
Current period provisions 0.0 0.0  
Write-offs charged against allowance 0.0 (0.8)  
Recoveries of amounts previously written off 0.0 0.0  
Columbia Operations      
Financing Receivable, Allowance for Credit Loss [Line Items]      
Allowance for Credit Loss 15.6 9.8 $ 10.2
Current period provisions 42.3 26.7  
Write-offs charged against allowance (50.8) (43.9)  
Recoveries of amounts previously written off $ 14.3 $ 16.8