Inventories, Net - Schedule of Inventories (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Inventory Disclosure [Abstract]
Raw materials	$ 52,019	$ 43,744
Work in process	28,283	25,957
Finished goods	2,023	14,251
Stores and spares	7,669	7,437
Packing material	999	540
Total Inventories	90,993	91,929
Less: Inventory allowance	(87)	(80)
Total inventories, net	$ 90,906	$ 91,849