Restructuring Costs - Severance Obligation (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Restructuring Cost and Reserve [Line Items]
Restructuring costs	$ 1,866,000	$ 65,000	$ 4,600,000	$ 268,000
2019 French Restructuring Obligation
Restructuring Cost and Reserve [Line Items]
Restructuring costs	1,259		3,198,000
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance			0
Payments			(1,837,000)
Foreign currency impact			(42,000)
Restructuring reserve, ending balance	895,000		895,000
2019 Corporate Restructuring Obligations
Restructuring Cost and Reserve [Line Items]
Restructuring costs	607,000		1,570,000
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance			0
Payments			(2,113,000)
Restructuring reserve, ending balance	853,000		853,000
Lyon France Workforce Reduction
Restructuring Cost and Reserve [Line Items]
Restructuring costs			168,000	268,000
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance			879,000	1,000,000
Charges for employee severance, benefits and other			(168,000)	268,000
Payments			(663,000)	(668,000)
Foreign currency impact			(10,000)	(19,000)
Restructuring reserve, ending balance	$ 38,000	$ 581,000	$ 38,000	$ 581,000