Restructuring Costs - Severance Obligation (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2021 USD ($)
2019 French Restructuring Obligation
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance	$ 248
Payments	(1)
Foreign currency impact	(8)
Restructuring reserve, ending balance	117
2019 French Restructuring Obligation | Employee Severance
Restructuring Reserve [Roll Forward]
Charges (income) for employee severance, benefits and other costs	(122)
2019 Corporate Restructuring Obligations
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance	272
Payments	(102)
Restructuring reserve, ending balance	170
2019 Corporate Restructuring Obligations | Employee Severance
Restructuring Reserve [Roll Forward]
Charges (income) for employee severance, benefits and other costs	$ 0