Segment Reporting (Details 1) - USD ($) $ in Thousands	Jun. 30, 2016		Mar. 31, 2016	Dec. 31, 2015	Jun. 30, 2015		Mar. 31, 2015	Dec. 31, 2014
Segment Reporting [Abstract]
Assets, Net	$ 1,113,959	[1]		$ 1,103,310	$ 1,485,125	[2]
Cash and cash equivalents	257,591		$ 173,389	200,714	$ 205,868		$ 179,587	$ 270,861
Other assets	40,305			28,465
TOTAL ASSETS	$ 1,411,855			$ 1,332,489

[1] Segment assets include receivables, prepaids, inventories, property, plant and equipment, and mineral interest

[2] Segment assets include receivables, prepaids, inventories, property, plant and equipment, and mineral interests