Restructuring Expenses (Details) $ in Millions		3 Months Ended	12 Months Ended
	Feb. 15, 2017 Employee	Jun. 30, 2016 Employee	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Restructuring Cost and Reserve [Line Items]
Restructuring payments				$ 4.2
2017 Restructuring Plan [Member]
Restructuring Cost and Reserve [Line Items]
Number of positions eliminated | Employee	100
Employee severance I Restructuring Cost and Reserve
Restructuring Cost and Reserve [Line Items]
Restructuring expenses				3.7
Facility Closing I Restructuring Cost and Reserve
Restructuring Cost and Reserve [Line Items]
Restructuring expenses				$ 0.6
2016 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring expenses					$ 1.7
Number of positions eliminated | Employee		36
Restructuring payments					$ 1.7
Q4 2018 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring expenses			$ 1.3
Q1 2018 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring expenses			3.0
Restructuring payments			$ 3.0