v3.25.2
Stockholders' Equity - Reclassifications Out of Accumulated Other Comprehensive Income (Details) - USD ($)
$ in Millions
 3 Months Ended 6 Months Ended
Jun. 30, 2025
Jun. 30, 2024
Jun. 30, 2025
Jun. 30, 2024
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]        
Income before taxes $ 320.6 $ 266.7 $ 588.0 $ 454.3
Income tax expense (79.1) (67.8) (142.7) (108.4)
Net income 241.5 198.9 445.3 345.9
Unfunded Employee Benefit Obligations | Reclassification out of Accumulated Other Comprehensive Income [Member]        
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]        
Amortization of prior service costs [1] (1.3) (1.3) (2.7) (2.6)
Amortization of actuarial gains (losses) [1] 0.1 (0.1) 0.2 (0.2)
Income before taxes (1.2) (1.4) (2.5) (2.8)
Income tax expense 0.3 0.3 0.6 0.7
Net income $ (0.9) $ (1.1) $ (1.9) $ (2.1)
[1] These AOCI components are included in the computation of net pension and postretirement benefit costs. See Note 13, Employee Benefit Plans and Other Postretirement Benefits, for additional information.