Accumulated Other Comprehensive Loss (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2018 USD ($)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Accumulated other comprehensive loss at December 31, 2017	$ 30,806
Net current-period other comprehensive income	(755)
Accumulated other comprehensive loss at June 30, 2018	33,921
Foreign currency translation adjustments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Accumulated other comprehensive loss at December 31, 2017	(18,879)
Net current-period other comprehensive income	(755)
Accumulated other comprehensive loss at June 30, 2018	(19,634)
AOCI attributable to parent
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Accumulated other comprehensive loss at December 31, 2017	(18,879)
Accumulated other comprehensive loss at June 30, 2018	$ (19,634)