Summary of Significant Accounting Policies - The Balances in the Company's Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	$ 189,100	$ 166,682
Total other comprehensive income (loss)	411	(2,755)
Ending balance	194,253	176,223
Foreign Currency [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(13,974)	(14,602)
Other comprehensive income (loss) before reclassifications	411	(2,755)
Total other comprehensive income (loss)	411	(2,755)
Ending balance	(13,563)	(17,357)
Defined Benefit Pension Plans [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(1,799)	(1,747)
Other comprehensive income (loss) before reclassifications	0	0
Total other comprehensive income (loss)	0	0
Ending balance	(1,799)	(1,747)
Accumulated Other Comprehensive Income (Loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(15,773)	(16,349)
Other comprehensive income (loss) before reclassifications	411	(2,755)
Total other comprehensive income (loss)	411	(2,755)
Ending balance	$ (15,362)	$ (19,104)