v3.25.2
Stockholders' Equity - Changes in Accumulated Other Comprehensive Income by Component (Details)
$ in Millions
 6 Months Ended
Jun. 30, 2025
USD ($)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]  
Beginning balance $ 4,404.0
Ending balance 4,632.1
Unfunded Employee Benefit Obligations  
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]  
Beginning balance (43.5)
Other comprehensive loss before reclassifications, net of tax 0.0
Amounts reclassified from AOCI, net of tax 1.9
Ending balance (41.6)
Accumulated Other Comprehensive Loss  
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]  
Beginning balance (43.4)
Other comprehensive loss before reclassifications, net of tax 0.1
Amounts reclassified from AOCI, net of tax 1.9
Ending balance (41.4)
Foreign Exchange Contract | Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges  
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]  
Beginning balance (0.1)
Other comprehensive loss before reclassifications, net of tax 0.0
Amounts reclassified from AOCI, net of tax 0.0
Ending balance (0.1)
Marketable Debt Securities | Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges  
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]  
Beginning balance 0.2
Other comprehensive loss before reclassifications, net of tax 0.1
Amounts reclassified from AOCI, net of tax 0.0
Ending balance $ 0.3