Comprehensive Income - Schedule of Changes in Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Accumulated Other Comprehensive Income Loss [Line Items]
Balance	$ 149.4	$ 111.1
Balance	231.7	173.6
Pension and Other Postretirement Benefits Plan Cost
Accumulated Other Comprehensive Income Loss [Line Items]
Balance	(52.9)	(52.2)
Other comprehensive income before reclassifications	0.0	0.0
Amounts reclassified from accumulated other comprehensive loss	1.4	1.0
Net change in accumulated other comprehensive loss	1.4	1.0
Balance	(51.5)	(51.2)
Translation adjustments
Accumulated Other Comprehensive Income Loss [Line Items]
Balance	(11.7)	(16.1)
Other comprehensive income before reclassifications	(2.3)	4.6
Amounts reclassified from accumulated other comprehensive loss	0.0	0.0
Net change in accumulated other comprehensive loss	(2.3)	4.6
Balance	(14.0)	(11.5)
Accumulated Other Comprehensive Loss
Accumulated Other Comprehensive Income Loss [Line Items]
Balance	(64.6)	(68.3)
Other comprehensive income before reclassifications	(2.3)	4.6
Amounts reclassified from accumulated other comprehensive loss	1.4	1.0
Net change in accumulated other comprehensive loss	(0.9)	5.6
Balance	$ (65.5)	$ (62.7)