Consolidated statements of comprehensive income (loss) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ (58,351)	$ 19,808	$ (7,230)
Other comprehensive income (loss), net of tax :
Change in foreign currency translation adjustments	302	(85)	(304)
Pension benefit plan	361	(980)	(1,063)
Total comprehensive income (loss)	$ (57,688)	$ 18,743	$ (8,597)