v3.26.1
Fair Value Measurements: Other Fair Value Measurements (Details) - USD ($)
$ in Millions
Jun. 30, 2026
Dec. 31, 2025
Carrying Amount    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Long-term debt, including current maturities $ 4,403.9 $ 4,701.1
Fair Value    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Long-term debt, including current maturities $ 4,278.9 $ 4,639.0