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, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance			$ 93,033
Net current-period other comprehensive income	$ 210	$ 1,917	1,111	$ 6,832
Ending balance	94,812		94,812
Foreign Currency [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance			(32,342)
Other comprehensive income before reclassifications			1,111
Net current-period other comprehensive income			1,111
Ending balance	(31,231)		(31,231)
Defined Benefit Pension Plans [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance			(1,832)
Other comprehensive income before reclassifications			0
Net current-period other comprehensive income			0
Ending balance	(1,832)		(1,832)
Accumulated Other Comprehensive Income (Loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance			(34,174)
Other comprehensive income before reclassifications			1,111
Net current-period other comprehensive income			1,111
Ending balance	$ (33,063)		$ (33,063)