Reorganization and Restructuring (Details) $ in Millions	3 Months Ended			9 Months Ended		12 Months Ended
	Sep. 30, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Sep. 30, 2017 USD ($) position	Sep. 30, 2016 USD ($)	Dec. 31, 2016 USD ($) position	Dec. 31, 2015 USD ($)
Reorganization and Restructuring 2016
Restructuring Cost and Reserve [Line Items]
Reorganization and restructuring costs		$ 18.1		$ 13.5
Restructuring Reserve [Roll Forward]
Restructuring Reserve, beginning balance				7.6
Expense (benefit)				13.5
Payments and utilization				(17.9)
Foreign currency exchange effects				0.2
Restructuring Reserve, ending balance	$ 3.4	7.6		3.4		$ 7.6
Reorganization and Restructuring 2015
Restructuring Cost and Reserve [Line Items]
Reorganization and restructuring costs					$ 5.3		$ 11.6
Positions eliminated across the global workforce | position						1,100
Expected cost savings						$ 20.0
Cumulative pretax charges		18.0				18.0
Asset Related Adjustments | Reorganization and Restructuring 2016
Restructuring Reserve [Roll Forward]
Restructuring Reserve, beginning balance				0.0
Expense (benefit)				3.4
Payments and utilization				(3.4)
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				7.0
Expense (benefit)				7.5
Payments and utilization				(11.9)
Foreign currency exchange effects				0.2
Restructuring Reserve, ending balance	2.8	7.0		2.8		7.0
Severance Costs | Other Restructuring
Restructuring Cost and Reserve [Line Items]
Reorganization and restructuring costs	0.8			1.9
Severance Costs | Director | Executive Leadership and Board of Directors Restructuring
Restructuring Cost and Reserve [Line Items]
Reorganization and restructuring costs			$ 1.8		$ 4.3
Lease Terminations | Reorganization and Restructuring 2016
Restructuring Reserve [Roll Forward]
Restructuring Reserve, beginning balance				0.6
Expense (benefit)				0.4
Payments and utilization				(0.4)
Foreign currency exchange effects				0.0
Restructuring Reserve, ending balance	0.6	0.6		0.6		0.6
Benefit Program Termination | Reorganization and Restructuring 2016
Restructuring Reserve [Roll Forward]
Restructuring Reserve, beginning balance				0.0
Expense (benefit)				2.2
Payments and utilization				(2.2)
Foreign currency exchange effects				0.0
Restructuring Reserve, ending balance	0.0	$ 0.0		$ 0.0		$ 0.0
Minimum | Reorganization and Restructuring 2016
Restructuring Cost and Reserve [Line Items]
Positions eliminated across the global workforce | position				800
Expected cost savings				$ 8.0
Expected costs	10.0			$ 10.0
Minimum | Other Restructuring
Restructuring Cost and Reserve [Line Items]
Positions eliminated across the global workforce | position				200
Expected cost savings				$ 3.0
Expected costs	1.0			$ 1.0
Maximum | Reorganization and Restructuring 2016
Restructuring Cost and Reserve [Line Items]
Positions eliminated across the global workforce | position				900
Expected cost savings				$ 12.0
Expected costs	14.0			$ 14.0
Maximum | Other Restructuring
Restructuring Cost and Reserve [Line Items]
Positions eliminated across the global workforce | position				300
Expected cost savings				$ 4.0
Expected costs	$ 2.0			$ 2.0