Supplemental Accumulated Other Comprehensive Loss Information - Reclassifications Out of AOCI (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Accumulated Other Comprehensive Income (Loss) [Line Items]
Recognition of accumulated currency translation loss upon sale of equity method investment	$ 9.0	$ 0.0	$ 9.0	$ 0.0
Actuarial loss
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total expense before taxes	0.1	0.2	0.3	0.4
Prior service benefit
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total expense before taxes	(0.1)	(0.2)	(0.3)	(0.4)
Benefit Plans
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total expense before taxes	9.0	0.0	9.0	0.0
Less income tax benefit	0.0	0.0	0.0	0.0
Total expense, net of tax	$ 9.0	$ 0.0	$ 9.0	$ 0.0