CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ (14,641)	$ 1,655	$ (18,769)	$ 5,607	$ 19,808
Other comprehensive income (loss), net of tax:
Change in foreign currency translation adjustments	413	84	145	(117)	(85)
Pension benefit plan	416	13	2,568	(648)	(980)
Total comprehensive income (loss)	$ (13,812)	$ 1,752	$ (16,056)	$ 4,842	$ 18,743