Accumulated Other Comprehensive Loss - Rollforward of AOCI (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	$ 353,997	$ 351,010	$ 341,599	$ 334,619
Other comprehensive income (loss), before taxes	(19,483)	607	(28,636)	(4,462)
Tax expense	(9)	(8)	(17)	(15)
Total other comprehensive (loss) income, net of taxes	(19,492)	599	(28,653)	(4,477)
Ending balance	471,814	379,744	471,814	379,744
Foreign Currency Translations
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(34,401)	(27,993)	(25,219)	(22,908)
Other comprehensive income (loss), before taxes	(19,513)	582	(28,695)	(4,503)
Tax expense	0	0	0	0
Total other comprehensive (loss) income, net of taxes	(19,513)	582	(28,695)	(4,503)
Ending balance	(53,914)	(27,411)	(53,914)	(27,411)
Accumulated (Loss) Gain on Retirement Plan
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(993)	(1,010)	(1,014)	(1,019)
Other comprehensive income (loss), before taxes	30	25	59	41
Tax expense	(9)	(8)	(17)	(15)
Total other comprehensive (loss) income, net of taxes	21	17	42	26
Ending balance	(972)	(993)	(972)	(993)
Accumulated other comprehensive loss
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(35,394)	(29,003)	(26,233)	(23,927)
Total other comprehensive (loss) income, net of taxes	(19,492)	599	(28,653)	(4,477)
Ending balance	$ (54,886)	$ (28,404)	$ (54,886)	$ (28,404)