Restructuring Costs - Severance Obligation (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Restructuring Reserve [Roll Forward]
Restructuring costs	$ 1,228	$ 153
2019 Corporate Restructuring Obligations
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance	0
Restructuring costs	1,398
Payments	(754)
Restructuring reserve, ending balance	644
Lyon France Workforce Reduction
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance	879	1,000
Charges for employee severance, benefits and other	(170)	153
Restructuring costs	170
Payments	(638)	(359)
Foreign currency impact	(8)	30
Restructuring reserve, ending balance	$ 63	$ 824