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, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	$ 181,695	$ 162,410	$ 166,682	$ 154,638
Total other comprehensive income (loss)	611	(466)	(924)	1,069
Ending balance	187,598	163,820	187,598	163,820
Foreign Currency [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(16,137)	(14,716)	(14,602)	(16,251)
Other comprehensive income (loss) before reclassifications	611	(466)	(924)	1,069
Total other comprehensive income (loss)	611	(466)	(924)	1,069
Ending balance	(15,526)	(15,182)	(15,526)	(15,182)
Defined Benefit Pension Plans [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(1,747)	(2,029)	(1,747)	(2,029)
Other comprehensive income (loss) before reclassifications	0	0	0	0
Total other comprehensive income (loss)	0	0	0	0
Ending balance	(1,747)	(2,029)	(1,747)	(2,029)
Accumulated Other Comprehensive Income (Loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(17,884)	(16,745)	(16,349)	(18,280)
Other comprehensive income (loss) before reclassifications	611	(466)	(924)	1,069
Total other comprehensive income (loss)	611	(466)	(924)	1,069
Ending balance	$ (17,273)	$ (17,211)	$ (17,273)	$ (17,211)