Segment Reporting (Details 1) - USD ($) $ in Thousands		Sep. 30, 2019	Dec. 31, 2018	Sep. 30, 2018
Segment Reporting [Abstract]
Assets, Net	[1]	$ 1,520,442	$ 1,550,671	$ 1,429,100
Cash and cash equivalents		65,319	115,081	$ 104,746
Other assets		103,856	46,748
TOTAL ASSETS		$ 1,689,617	$ 1,712,500

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