Reorganization and Restructuring (Details) $ in Millions	1 Months Ended	3 Months Ended			9 Months Ended		12 Months Ended
	Jan. 31, 2016 USD ($) director	Dec. 31, 2015 USD ($)	Sep. 30, 2015 USD ($)	Dec. 31, 2014 employee	Sep. 30, 2016 USD ($) employee	Sep. 30, 2015 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
2015 Reorganization and Restructuring
Restructuring Cost and Reserve [Line Items]
Reorganization and restructuring costs			$ 11.6		$ 5.3
Positions eliminated across the global workforce | employee					1,100
Cumulative pretax charges					$ 17.0
Restructuring Reserve [Roll Forward]
Restructuring Reserve, beginining balance	$ 6.3				6.3
Expense (benefit)					5.3
Payments and utilization					(8.9)
Foreign currency exchange effects					0.1
Restructuring Reserve, ending balance		$ 6.3			2.8		$ 6.3
2014 Reorganization and Restructuring
Restructuring Cost and Reserve [Line Items]
Positions eliminated across the global workforce | employee				1,700
Expected cost savings							50.0
Restructuring Reserve [Roll Forward]
Expense (benefit)						$ 1.2		$ 21.8
Severance Costs | 2015 Reorganization and Restructuring
Restructuring Reserve [Roll Forward]
Restructuring Reserve, beginining balance	$ 6.3				6.3
Expense (benefit)					3.0
Payments and utilization					(7.5)
Foreign currency exchange effects					0.1
Restructuring Reserve, ending balance		6.3			1.9		6.3
Severance Costs | 2014 Reorganization and Restructuring
Restructuring Reserve [Roll Forward]
Cumulative pretax charges		24.0					24.0
Severance Costs | Director | Executive Leadership and Board of Directors Restructuring
Restructuring Cost and Reserve [Line Items]
Reorganization and restructuring costs		1.8			4.3
Positions eliminated across the global workforce | director	2
Severance Costs | Executive Officer | Executive Leadership and Board of Directors Restructuring
Restructuring Reserve [Roll Forward]
Restructuring Reserve, ending balance					1.4
Contract Terminations | 2015 Reorganization and Restructuring
Restructuring Reserve [Roll Forward]
Restructuring Reserve, beginining balance	$ 0.0				0.0
Expense (benefit)					0.8
Payments and utilization					(0.2)
Foreign currency exchange effects					0.0
Restructuring Reserve, ending balance		0.0			0.6		0.0
Lease Terminations | 2015 Reorganization and Restructuring
Restructuring Reserve [Roll Forward]
Restructuring Reserve, beginining balance	$ 0.0				0.0
Expense (benefit)					1.5
Payments and utilization					(1.2)
Foreign currency exchange effects					0.0
Restructuring Reserve, ending balance		$ 0.0			0.3		$ 0.0
Minimum | 2015 Reorganization and Restructuring
Restructuring Cost and Reserve [Line Items]
Expected cost savings					20.0
Maximum | 2015 Reorganization and Restructuring
Restructuring Cost and Reserve [Line Items]
Expected cost savings					$ 25.0