INVESTMENT IN AMAK - Summary of Operating Results (Details) - AMAK [Member] - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Schedule of Equity Method Investments [Line Items]
Sales	$ 19,494	$ 0	$ 33,581	$ 2,256
Cost of sales	16,555	8,901	29,061	12,463
Gross profit (loss)	2,939	(8,901)	4,520	(10,207)
General, administrative and other expenses	3,265	1,971	5,166	4,559
Net Loss	(326)	(10,872)	(646)	(14,766)
Depreciation and amortization	8,281	7,609	15,982	10,664
Net income (loss) before depreciation and amortization	$ 7,955	$ (3,263)	$ 15,336	$ (4,102)