Reorganization and Restructuring (Details) $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2018 USD ($) position	Mar. 31, 2017 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Reorganization and Restructuring 2016
Restructuring Cost and Reserve [Line Items]
Expected cost savings	$ 20.0
Restructuring Reserve [Roll Forward]
Restructuring Reserve, beginning balance	2.0	$ 7.6	$ 7.6
Expense (benefit)	2.7	2.8	17.3	$ 18.1
Payments and utilization	(3.2)	(5.3)
Foreign currency exchange effects	0.1
Restructuring Reserve, ending balance	1.6	5.1	2.0	7.6
Other Restructuring
Restructuring Cost and Reserve [Line Items]
Expected cost savings	4.0
Asset Related Adjustments | Reorganization and Restructuring 2016
Restructuring Reserve [Roll Forward]
Restructuring Reserve, beginning balance	0.0	0.0	0.0
Expense (benefit)	1.2	1.0
Payments and utilization	(1.2)	(1.0)
Foreign currency exchange effects	0.0
Restructuring Reserve, ending balance	0.0	0.0	0.0	0.0
Severance Costs | Reorganization and Restructuring 2016
Restructuring Reserve [Roll Forward]
Restructuring Reserve, beginning balance	1.6	7.0	7.0
Expense (benefit)	1.5	1.8
Payments and utilization	(1.9)	(4.5)
Foreign currency exchange effects	0.1
Restructuring Reserve, ending balance	1.3	4.3	1.6	7.0
Severance Costs | Other Restructuring
Restructuring Reserve [Roll Forward]
Expense (benefit)	1.0
Lease Terminations | Reorganization and Restructuring 2016
Restructuring Reserve [Roll Forward]
Restructuring Reserve, beginning balance	0.4	0.6	0.6
Expense (benefit)	0.0	0.0
Payments and utilization	(0.1)	0.2
Foreign currency exchange effects	0.0
Restructuring Reserve, ending balance	$ 0.3	$ 0.8	$ 0.4	$ 0.6
Minimum | Reorganization and Restructuring 2016
Restructuring Cost and Reserve [Line Items]
Positions eliminated across the global workforce | position	800
Expected costs	$ 7.0
Minimum | Other Restructuring
Restructuring Cost and Reserve [Line Items]
Positions eliminated across the global workforce | position	200
Expected costs	$ 1.0
Maximum | Reorganization and Restructuring 2016
Restructuring Cost and Reserve [Line Items]
Positions eliminated across the global workforce | position	900
Expected costs	$ 9.0
Maximum | Other Restructuring
Restructuring Cost and Reserve [Line Items]
Positions eliminated across the global workforce | position	300
Expected costs	$ 3.0