v3.25.4
Fair Value (Fair Value Of Financial Assets And Liabilities Measured On A Recurring Basis) (Details) - USD ($)
$ in Millions
Dec. 31, 2025
Dec. 31, 2024
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]    
Risk management assets $ 18.8  
Available-for-sale debt securities 146.1 $ 86.7
Total 173.4 193.8
Risk management liabilities 5.9 3.5
Total 5.9 3.5
Financial Instruments, Owned, US Government and Agency Obligations, at Fair Value   80.1
Equity Securities, FV-NI 8.5  
Cash Flow Hedging    
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]    
Risk management assets   27.0
Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]    
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]    
Risk management assets 0.0 0.0
Available-for-sale debt securities 0.0 0.0
Total 8.5 80.1
Risk management liabilities 0.0 0.0
Total 0.0 0.0
Financial Instruments, Owned, US Government and Agency Obligations, at Fair Value   80.1
Equity Securities, FV-NI 8.5  
Significant Other Observable Inputs (Level 2) [Member]    
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]    
Risk management assets   27.0
Available-for-sale debt securities 146.1 86.7
Total 164.9 113.7
Derivative Liability Statement Of Financial Position Extensible Enumeration Not Disclosed Flag   3.5
Risk management liabilities 5.9  
Total 5.9 3.5
Derivative Asset Statement Of Financial Position Extensible Enumeration Not Disclosed Flag 18.8  
Financial Instruments, Owned, US Government and Agency Obligations, at Fair Value   0.0
Equity Securities, FV-NI 0.0  
Significant Unobservable Inputs (Level 3) [Member]    
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]    
Risk management assets 0.0 0.0
Available-for-sale debt securities 0.0 0.0
Total 0.0 0.0
Risk management liabilities 0.0 0.0
Total 0.0 0.0
Financial Instruments, Owned, US Government and Agency Obligations, at Fair Value   $ 0.0
Equity Securities, FV-NI $ 0.0