Segment Reporting (Details 1) - USD ($) $ in Thousands		Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019
Segment Reporting [Abstract]
Assets, Net	[1]	$ 1,203,594	$ 1,215,783	$ 1,548,399
Cash and cash equivalents		52,895	55,645	$ 69,033
Other assets		92,608	107,208
TOTAL ASSETS		$ 1,349,097	$ 1,378,636

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