Stockholders' Equity - Changes in Each Component of Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance			$ (81.3)
Net current-period other comprehensive income (loss)	$ 3.9	$ (4.1)	(0.2)	$ 0.2
Ending balance	(81.5)		(81.5)
Actuarial Losses
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(68.8)	(68.7)	(69.7)	(68.6)
Other comprehensive (loss) income before reclassifications	(0.8)	0.3	(0.9)	(0.6)
Amounts reclassified from accumulated other comprehensive loss	0.6	0.5	1.6	1.3
Net current-period other comprehensive income (loss)	(0.2)	0.8	0.7	0.7
Ending balance	(69.0)	(67.9)	(69.0)	(67.9)
Prior Service Costs
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(1.9)	(2.0)	(2.0)	(2.0)
Other comprehensive (loss) income before reclassifications	0.0	0.0	0.0	0.0
Amounts reclassified from accumulated other comprehensive loss	0.0	0.1	0.1	0.1
Net current-period other comprehensive income (loss)	0.0	0.1	0.1	0.1
Ending balance	(1.9)	(1.9)	(1.9)	(1.9)
Currency Translation
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(15.4)	(11.3)	(10.1)	(16.0)
Other comprehensive (loss) income before reclassifications	5.6	(5.1)	0.3	(0.4)
Amounts reclassified from accumulated other comprehensive loss	0.0	0.0	0.0	0.0
Net current-period other comprehensive income (loss)	5.6	(5.1)	0.3	(0.4)
Ending balance	(9.8)	(16.4)	(9.8)	(16.4)
Interest Rate Swaps
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	0.7	2.3	0.5	2.6
Other comprehensive (loss) income before reclassifications	(1.1)	0.8	0.5	1.5
Amounts reclassified from accumulated other comprehensive loss	(0.4)	(0.7)	(1.8)	(1.7)
Net current-period other comprehensive income (loss)	(1.5)	0.1	(1.3)	(0.2)
Ending balance	(0.8)	2.4	(0.8)	2.4
Accumulated Other Comprehensive Loss
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(85.4)	(79.7)	(81.3)	(84.0)
Other comprehensive (loss) income before reclassifications	3.7	(4.0)	(0.1)	0.5
Amounts reclassified from accumulated other comprehensive loss	0.2	(0.1)	(0.1)	(0.3)
Net current-period other comprehensive income (loss)	3.9	(4.1)	(0.2)	0.2
Ending balance	$ (81.5)	$ (83.8)	$ (81.5)	$ (83.8)