Summary of Significant Accounting Policies - The Balances in the Company's Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	$ 176,223	$ 158,426	$ 166,682	$ 154,638
Total other comprehensive income (loss)	1,220	758	(1,535)	1,535
Ending balance	181,695	162,410	181,695	162,410
Foreign Currency [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance			(14,602)
Other comprehensive income (loss) before reclassifications			(1,535)
Total other comprehensive income (loss)			(1,535)
Ending balance	(16,137)		(16,137)
Defined Benefit Pension Plans [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance			(1,747)
Other comprehensive income (loss) before reclassifications			0
Total other comprehensive income (loss)			0
Ending balance	(1,747)		(1,747)
Accumulated Other Comprehensive Income (Loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(19,104)	(17,503)	(16,349)	(18,280)
Other comprehensive income (loss) before reclassifications			(1,535)
Total other comprehensive income (loss)			(1,535)
Ending balance	$ (17,884)	$ (16,745)	$ (17,884)	$ (16,745)