Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance		$ 258,870
Other comprehensive income (loss)		8,790	$ (9,611)	$ (3,249)
Amounts reclassified from accumulated other comprehensive income (loss)	[1]	1,045	726	875
Ending Balance		311,545	258,870
Total Accumulated Other Foreign Currency Comprehensive Translation Pension Income (Loss)
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance		(27,715)	(18,830)	(16,456)
Ending Balance		(17,880)	(27,715)	(18,830)
Cumulative Translation Adjustments
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance		(17,222)	(9,698)	(5,615)
Other comprehensive income (loss)		8,909	(7,524)	(4,083)
Ending Balance		(8,313)	(17,222)	(9,698)
Pension Liability Adjustments
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance		(10,493)	(9,132)	(10,841)
Other comprehensive income (loss)		(119)	(2,087)	834
Amounts reclassified from accumulated other comprehensive income (loss)	[1]	1,045	726	875
Ending Balance		$ (9,567)	$ (10,493)	$ (9,132)

[1] The amounts reclassified from accumulated other comprehensive income (loss) were included in selling, general and administrative expenses in the consolidated statements of operations.