Inventories (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Inventory Disclosure [Abstract]
Raw materials	$ 52,480	$ 60,697
Finished goods	109,270	111,600
Spare parts	13,294	12,324
Inventory, Net	175,044	184,621
Inventory Valuation Reserves	$ 12,736	$ 12,626