Restructuring Costs - Severance Obligation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Restructuring Reserve [Roll Forward]
Beginning balance of accrued costs	$ 879	$ 1,000
Charges for employee severance, benefits and other	(169)	1,164
Payments	(673)	(1,261)
Foreign currency impact	(9)	(24)
Ending balance of accrued costs	28	879
2019 French Restructuring Obligation
Restructuring Reserve [Roll Forward]
Beginning balance of accrued costs	0
Charges for employee severance, benefits and other	4,855
Payments	(2,441)
Foreign currency impact	24
Ending balance of accrued costs	1,922	0
2019 Corporate Restructuring Obligations
Restructuring Reserve [Roll Forward]
Beginning balance of accrued costs	0
Charges for employee severance, benefits and other	1,755
Payments	(2,326)
Ending balance of accrued costs	1,080	$ 0
Employee Severance | 2019 French Restructuring Obligation
Restructuring Reserve [Roll Forward]
Charges for employee severance, benefits and other costs	4,339
Employee Severance | 2019 Corporate Restructuring Obligations
Restructuring Reserve [Roll Forward]
Charges for employee severance, benefits and other	$ 3,406