Accumulated Other Comprehensive Loss (Components of accumulated comprehensive loss) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Increase (Decrease) in Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at beginning of period			$ 288.0
Other comprehensive income (loss)	$ (2.6)	$ 7.7	(7.4)	$ 19.5
Balance at end of period	315.8		315.8
Cumulative Translation Adjustment
Increase (Decrease) in Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at beginning of period			(11.6)	(30.8)
Other comprehensive income (loss)			(8.9)	18.9
Balance at end of period	(20.5)	(11.9)	(20.5)	(11.9)
Pension and Postretirement Benefits
Increase (Decrease) in Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at beginning of period			(6.3)	(11.9)
Other comprehensive income (loss)			1.5	0.6
Balance at end of period	(4.8)	(11.3)	(4.8)	(11.3)
Total
Increase (Decrease) in Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at beginning of period			(17.9)	(42.7)
Balance at end of period	$ (25.3)	$ (23.2)	$ (25.3)	$ (23.2)