Inventories, net (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Inventory Disclosure [Abstract]
Raw materials and supplies	$ 61,404	$ 70,188
Work in progress	56,196	65,382
Finished goods	226,624	239,083
Inventory, gross, total	344,224	374,653
Less: allowance for obsolete and excess inventory	(80,128)	(83,566)
Total inventory	$ 264,096	$ 291,087