Reorganization and Restructuring Reorganization and Restructuring - Narrative (Details) $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2016 USD ($)	Dec. 31, 2018 USD ($) position	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($) position
Reorganization and Restructuring 2016
Restructuring Cost and Reserve [Line Items]
Cumulative pretax charges		$ 48.0
Positions eliminated across the global workforce | position		800
Restructuring Reserve [Roll Forward]
Restructuring Reserve, beginning balance		$ 2.0	$ 7.6	$ 0.0
Expense (benefit)	$ 18.1	13.0	17.3	18.1
Payments and utilization		(14.3)	(23.1)	(10.5)
Foreign currency exchange effects		0.0	0.2
Restructuring Reserve, ending balance	7.6	0.7	2.0	7.6
Reorganization and Restructuring 2015
Restructuring Cost and Reserve [Line Items]
Cumulative pretax charges	18.0			$ 18.0
Positions eliminated across the global workforce | position				1,100
Cost savings				$ 20.0
Restructuring Reserve [Roll Forward]
Expense (benefit)				6.5
Asset Related Adjustments | Reorganization and Restructuring 2016
Restructuring Reserve [Roll Forward]
Restructuring Reserve, beginning balance		0.0	0.0	0.0
Expense (benefit)		1.7	4.1	16.3
Payments and utilization		(1.7)	(4.1)	(16.3)
Foreign currency exchange effects		0.0	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	0.0
Expense (benefit)		11.3	10.4	7.2
Payments and utilization		(12.4)	(16.0)	(0.2)
Foreign currency exchange effects		0.0	0.2
Restructuring Reserve, ending balance	7.0	0.5	1.6	7.0
Severance Costs | Executive Leadership and Board of Directors Restructuring
Restructuring Cost and Reserve [Line Items]
Cumulative pretax charges	4.3			4.3
Severance Costs | Other Restructuring
Restructuring Reserve [Roll Forward]
Expense (benefit)		7.6	4.6
Lease Terminations | Reorganization and Restructuring 2016
Restructuring Reserve [Roll Forward]
Restructuring Reserve, beginning balance		0.4	0.6	0.0
Expense (benefit)		0.0	0.6	0.7
Payments and utilization		(0.2)	(0.8)	(0.1)
Foreign currency exchange effects		0.0	0.0
Restructuring Reserve, ending balance	0.6	0.2	0.4	0.6
Benefit Program Termination | Reorganization and Restructuring 2016
Restructuring Reserve [Roll Forward]
Restructuring Reserve, beginning balance		0.0	0.0	0.0
Expense (benefit)		0.0	2.2	(6.1)
Payments and utilization		0.0	(2.2)	6.1
Foreign currency exchange effects		0.0	0.0
Restructuring Reserve, ending balance	$ 0.0	0.0	$ 0.0	$ 0.0
Minimum | Other Restructuring
Restructuring Cost and Reserve [Line Items]
Expected costs		5.0
Maximum | Other Restructuring
Restructuring Cost and Reserve [Line Items]
Expected costs		$ 7.0