Summary of Significant Accounting Policies - The Balances in the Company's Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	$ 201,981	$ 181,695	$ 189,100	$ 166,682
Total other comprehensive income (loss)	(874)	611	7	(924)
Ending balance	205,525	187,598	205,525	187,598
Foreign Currency [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(13,093)	(16,137)	(13,974)	(14,602)
Other comprehensive income (loss) before reclassifications	(874)	611	7	(924)
Total other comprehensive income (loss)	(874)	611	7	(924)
Ending balance	(13,967)	(15,526)	(13,967)	(15,526)
Defined Benefit Pension Plans [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(1,799)	(1,747)	(1,799)	(1,747)
Other comprehensive income (loss) before reclassifications	0	0	0	0
Total other comprehensive income (loss)	0	0	0	0
Ending balance	(1,799)	(1,747)	(1,799)	(1,747)
Accumulated Other Comprehensive Income (Loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(14,892)	(17,884)	(15,773)	(16,349)
Other comprehensive income (loss) before reclassifications	(874)	611	7	(924)
Total other comprehensive income (loss)	(874)	611	7	(924)
Ending balance	$ (15,766)	$ (17,273)	$ (15,766)	$ (17,273)