v3.26.3
Fair Value - Financial Assets and Liabilities Not Recorded at FV (Details) - USD ($)
$ in Millions
Sep. 30, 2026
Dec. 31, 2025
Financial Assets    
Cash and cash equivalents $ 109.0 $ 499.2
Financial Liabilities    
Short-term investments, fair value   351.4
Debt, current and long-term 3,076.6 3,786.5
Long-term finance lease obligation   1.7
Unsecured Debt    
Financial Liabilities    
Unamortized debt issuance costs 4.7 5.5
Carrying Amount    
Financial Assets    
Cash and cash equivalents 109.0 499.2
Financial Liabilities    
Short-term investments, carrying amount   351.3
Debt, current and long-term 3,237.4 3,785.2
Estimated Fair Value | Level 1    
Financial Assets    
Cash and cash equivalents 109.0 499.2
Financial Liabilities    
Short-term investments, fair value   351.4
Debt, current and long-term 0.0 0.0
Estimated Fair Value | Level 2    
Financial Assets    
Cash and cash equivalents 0.0 0.0
Financial Liabilities    
Short-term investments, fair value   0.0
Debt, current and long-term 3,076.6 3,786.5
Estimated Fair Value | Level 3    
Financial Assets    
Cash and cash equivalents 0.0 0.0
Financial Liabilities    
Short-term investments, fair value   0.0
Debt, current and long-term $ 0.0 $ 0.0