Other Comprehensive Loss (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Foreign currency translation gain	$ (8,567)	$ (22,370)
Changes in defined benefit plan liabilities	(3,627)	(3,716)
Unrealized holding gains on available-for-sale securities	2,174	926
Total accumulated other comprehensive loss	$ (10,020)	$ (25,160)