Inventory and Ore on Leach Pads (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Inventory Disclosure [Abstract]
Inventory, Finished Goods, Net of Reserves	$ 6,831	$ 17,994
Other Inventory, Net of Reserves	18,803	41,955
Inventory, Supplies, Net of Reserves	32,596	33,487
Inventory	58,230	93,436
Ore on Leach Pad, Current	73,752	64,167
Ore on leach pads, noncurrent	65,393	67,231
Inventory, Ore Stockpiles on Leach Pads, Gross	139,145	131,398
Inventory and Ore on Leach Pads	$ 197,375	$ 224,834