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, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	$ 162,410	$ 181,261	$ 154,638	$ 93,752
Total other comprehensive income (loss)	(466)	649	1,069	(1,308)
Ending balance	163,820	159,057	163,820	159,057
Foreign Currency [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance			(16,251)
Other comprehensive income (loss) before reclassifications			1,069
Total other comprehensive income (loss)			1,069
Ending balance	(15,182)		(15,182)
Defined Benefit Pension Plans [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance			(2,029)
Other comprehensive income (loss) before reclassifications			0
Total other comprehensive income (loss)			0
Ending balance	(2,029)		(2,029)
Accumulated Other Comprehensive Income (Loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(16,745)	(16,498)	(18,280)	(14,541)
Other comprehensive income (loss) before reclassifications			1,069
Total other comprehensive income (loss)			1,069
Ending balance	$ (17,211)	$ (15,849)	$ (17,211)	$ (15,849)