Inventories, Net (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Inventory Disclosure [Abstract]
Finished goods	$ 84,523	$ 79,226
Work in process	13,633	15,447
Raw materials and supplies	94,807	88,895
Inventories, net	192,963	183,568
Inventory valuation reserves	$ 33,100	$ 34,400