Comprehensive Income - Schedule of Changes in Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Accumulated Other Comprehensive Income Loss [Line Items]
Balance	$ 247.8	$ 268.6
Balance	276.0	267.1
Pension and Other Postretirement Benefits Plan Cost
Accumulated Other Comprehensive Income Loss [Line Items]
Balance	(67.6)	(70.9)
Other comprehensive income before reclassifications	0.0	0.0
Amounts reclassified from accumulated other comprehensive loss	0.6	0.6
Net change in accumulated other comprehensive loss	0.6	0.6
Balance	(67.0)	(70.3)
Translation adjustments
Accumulated Other Comprehensive Income Loss [Line Items]
Balance	(13.2)	(13.7)
Other comprehensive income before reclassifications	0.9	(2.8)
Amounts reclassified from accumulated other comprehensive loss	0.0	0.0
Net change in accumulated other comprehensive loss	0.9	(2.8)
Balance	(12.3)	(16.5)
Accumulated Other Comprehensive Loss
Accumulated Other Comprehensive Income Loss [Line Items]
Balance	(80.8)	(84.6)
Other comprehensive income before reclassifications	0.9	(2.8)
Amounts reclassified from accumulated other comprehensive loss	0.6	0.6
Net change in accumulated other comprehensive loss	1.5	(2.2)
Balance	$ (79.3)	$ (86.8)