Stockholders' Equity - Changes in Each Component of Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance			$ (81.3)
Net current-period other comprehensive income (loss)	$ (1.3)	$ 3.7	(4.1)	$ 4.3
Ending balance	(85.4)		(85.4)
Actuarial Losses
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(69.1)	(68.6)	(69.7)	(68.6)
Other comprehensive (loss) income before reclassifications	(0.2)	(0.5)	(0.1)	(0.9)
Amounts reclassified from accumulated other comprehensive loss	0.5	0.4	1.0	0.8
Net current-period other comprehensive income (loss)	0.3	(0.1)	0.9	(0.1)
Ending balance	(68.8)	(68.7)	(68.8)	(68.7)
Prior Service Costs
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(2.0)	(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	0.1	0.0	0.1	0.0
Net current-period other comprehensive income (loss)	0.1	0.0	0.1	0.0
Ending balance	(1.9)	(2.0)	(1.9)	(2.0)
Currency Translation
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(14.0)	(14.5)	(10.1)	(16.0)
Other comprehensive (loss) income before reclassifications	(1.4)	3.2	(5.3)	4.7
Amounts reclassified from accumulated other comprehensive loss	0.0	0.0	0.0	0.0
Net current-period other comprehensive income (loss)	(1.4)	3.2	(5.3)	4.7
Ending balance	(15.4)	(11.3)	(15.4)	(11.3)
Interest Rate Swaps
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	1.0	1.7	0.5	2.6
Other comprehensive (loss) income before reclassifications	0.4	1.1	1.6	0.7
Amounts reclassified from accumulated other comprehensive loss	(0.7)	(0.5)	(1.4)	(1.0)
Net current-period other comprehensive income (loss)	(0.3)	0.6	0.2	(0.3)
Ending balance	0.7	2.3	0.7	2.3
Accumulated Other Comprehensive Loss
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(84.1)	(83.4)	(81.3)	(84.0)
Other comprehensive (loss) income before reclassifications	(1.2)	3.8	(3.8)	4.5
Amounts reclassified from accumulated other comprehensive loss	(0.1)	(0.1)	(0.3)	(0.2)
Net current-period other comprehensive income (loss)	(1.3)	3.7	(4.1)	4.3
Ending balance	$ (85.4)	$ (79.7)	$ (85.4)	$ (79.7)

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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Amount, after tax, of accumulated increase (decrease) in equity from transaction and other event and circumstance from nonowner source.

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Amount after tax, before reclassification adjustments, of other comprehensive income (loss), attributable to parent.

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Amount after tax of other comprehensive income (loss) attributable to parent entity.

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