v3.26.1
Stockholders' Equity - Reclassifications Out of Accumulated Other Comprehensive Income (Details) - USD ($)
$ in Millions
 3 Months Ended 6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]        
Income before taxes $ 259.0 $ 320.6 $ 478.7 $ 588.0
Income tax benefit (66.9) (79.1) (115.7) (142.7)
Net income 192.1 241.5 363.0 445.3
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] (1.2) (1.3) (2.5) (2.7)
Amortization of actuarial losses [1] 0.0 0.1 0.0 0.2
Income before taxes (1.2) (1.2) (2.5) (2.5)
Income tax benefit 0.3 0.3 0.6 0.6
Net income $ (0.9) $ (0.9) $ (1.9) $ (1.9)
[1] These AOCI components are included in the computation of net pension and postretirement benefit costs. See Note 14, Employee Benefit Plans and Other Postretirement Benefits, for additional information.