Inventories, Net (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Inventory Disclosure [Abstract]
Finished goods	$ 86,541	$ 76,981
Work in process	8,196	13,870
Raw materials and supplies	72,964	82,794
Inventories, net	167,701	173,645
Inventory valuation reserves	$ 46,900	$ 46,500