Accumulated Other Comprehensive Loss (Components of accumulated comprehensive loss) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Increase (Decrease) in Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance			$ 292.0
Other comprehensive loss adjustments	$ (10.3)	$ 7.7	(4.8)	$ 11.9
Ending balance	316.3		316.3
Cumulative Translation Adjustment
Increase (Decrease) in Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance			(11.6)	(30.8)
Other comprehensive loss adjustments			(6.2)	11.5
Ending balance	(17.8)	(19.3)	(17.8)	(19.3)
Pension and Postretirement Benefits
Increase (Decrease) in Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance			(6.3)	(11.9)
Other comprehensive loss adjustments			1.4	0.4
Ending balance	(4.9)	(11.5)	(4.9)	(11.5)
Total
Increase (Decrease) in Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance			(17.9)	(42.7)
Ending balance	$ (22.7)	$ (30.8)	$ (22.7)	$ (30.8)