v3.26.1
Accumulated Other Comprehensive Income - Schedule of Accumulated Other Comprehensive Income (Details) - USD ($)
$ in Millions
 3 Months Ended 6 Months Ended
Jun. 30, 2026
Mar. 31, 2026
Jun. 30, 2025
Mar. 31, 2025
Jun. 30, 2026
Jun. 30, 2025
AOCI Attributable to Parent, Net of Tax [Roll Forward]            
Beginning balance $ 877.3 $ 826.1 $ 756.8 $ 743.1 $ 826.1 $ 743.1
Other comprehensive (loss) income, net of tax (22.3) 5.2 4.1 2.6 (17.1) 6.7
Ending balance 943.8 877.3 776.0 756.8 943.8 776.0
Defined Benefit Plans:            
AOCI Attributable to Parent, Net of Tax [Roll Forward]            
Beginning balance 22.7 22.5 19.2 19.1 22.5 19.1
Less: income tax expense [1] (0.1)   (0.1)   (0.2) (0.2)
Net gain (loss) reclassified from AOCI to Net income 0.2   0.4   0.4 0.6
Other comprehensive (loss) income, net of tax 0.2   0.4   0.4 0.5
Ending balance 22.9 22.7 19.6 19.2 22.9 19.6
Defined Benefit Plans: Actuarial Loss            
AOCI Attributable to Parent, Net of Tax [Roll Forward]            
Unrealized (loss) gain on cash flow hedges       (0.0)   (0.1)
Net unrealized (loss) gain on cash flow hedges           (0.1)
Reclassification of unrealized gain upon settlement of cash flow hedges [2] (0.6)   (0.5)   (1.2) (1.1)
Defined Benefit Plans: Net Prior Service Cost            
AOCI Attributable to Parent, Net of Tax [Roll Forward]            
Reclassification of unrealized gain upon settlement of cash flow hedges [2] 0.9   1.0   1.8 1.9
Cash Flow Hedges:            
AOCI Attributable to Parent, Net of Tax [Roll Forward]            
Beginning balance 9.3 4.3 3.9 1.4 4.3 1.4
Unrealized (loss) gain on cash flow hedges (16.6)   7.5   (0.8) 16.2
Less: income tax benefit (expense) 3.9   (1.8)   0.2 (3.8)
Net unrealized (loss) gain on cash flow hedges (12.7)   5.7   (0.6) 12.4
Reclassification of unrealized gain upon settlement of cash flow hedges (12.8)   (2.5)   (22.1) (8.0)
Less: income tax expense [1] 3.0   0.5   5.2 1.8
Net gain (loss) reclassified from AOCI to Net income (9.8)   (2.0)   (16.9) (6.2)
Other comprehensive (loss) income, net of tax (22.5)   3.7   (17.5) 6.2
Ending balance (13.2) [3] 9.3 7.6 [3] 3.9 (13.2) [3] 7.6 [3]
Accumulated Other Comprehensive Income (Loss)            
AOCI Attributable to Parent, Net of Tax [Roll Forward]            
Beginning balance 32.0 26.8 23.1 20.5 26.8 20.5
Other comprehensive (loss) income, net of tax (22.3) 5.2 4.1 2.6    
Ending balance $ 9.7 $ 32.0 $ 27.2 $ 23.1 $ 9.7 $ 27.2
[1] Income tax amounts reclassified out of AOCI were included as a component of Income tax provision.
[2] Amounts amortized out of AOCI related to pension and other postretirement and postemployment benefits were included within Net periodic postretirement and postemployment benefit cost (see Note 3).
[3] As of June 30, 2026, we estimate a net mark-to-market loss before tax of $17.6 million in AOCI will be reclassified into Net income upon settlement within the next 12 months.