Restructuring Costs - Severance Obligation (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
2019 Corporate Restructuring Obligations
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance			$ 1,080	$ 0
Payments	$ (440)	$ (2,016)
Restructuring reserve, ending balance	746	343	746	343
2019 French Restructuring Obligation
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance			1,922	0
Payments			(1,784)	(1,332)
Foreign currency impact			(48)	20
Restructuring reserve, ending balance	263	1,102	263	1,102
Employee Severance | 2019 Corporate Restructuring Obligations
Restructuring Reserve [Roll Forward]
Restructuring costs	$ 106	$ 2,359
Employee Severance | 2019 French Restructuring Obligation
Restructuring Reserve [Roll Forward]
Restructuring costs			$ 173	$ 2,414