Restructuring Activities - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Restructuring Cost and Reserve [Line Items]
Restructuring expenses	$ 2,206	$ 2,292
2015 California manufacturing operations restructuring plan
Restructuring Cost and Reserve [Line Items]
Restructuring expenses		400
Employee severance | Severance liability and post employment benefits in connection with Globus transaction
Restructuring Cost and Reserve [Line Items]
Restructuring expenses	$ 2,200	$ 1,900