Quarterly report pursuant to Section 13 or 15(d)

INVESTMENT IN AMAK (Details)

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INVESTMENT IN AMAK (Details)
$ / shares in Units, $ in Thousands
 3 Months Ended 9 Months Ended
Jul. 31, 2016
$ / shares
shares
Sep. 30, 2017
USD ($)
SAR / $
Sep. 30, 2016
USD ($)
Sep. 30, 2017
USD ($)
SAR / $
Sep. 30, 2016
USD ($)
Dec. 31, 2016
USD ($)
Jul. 31, 2016
SAR / shares
shares
Jun. 30, 2016
Results of Operations [Abstract]                
Loss from operations   $ 3,965 $ 4,128 $ 13,319 $ 16,169      
Equity in Income or Loss of AMAK Reflected on Consolidated Statement Of Operation [Abstract]                
Equity in earnings (loss) of AMAK   $ (897) (2,089) $ (5,161) 2,261      
AMAK [Member]                
Schedule of Equity Method Investments [Line Items]                
Shares issued (in shares) | shares 4,000,000              
Percentage investment in AMAK 35.25% 33.44%   33.44%   33.44% 35.25% 33.44%
Investment in AMAK   $ 44,200   $ 44,200   $ 49,400    
Exchange rate | SAR / $   3.75   3.75        
Results of Operations [Abstract]                
Sales   $ 9,709 318 $ 11,965 9,921      
Gross loss   (1,307) (4,747) (11,515) (7,556)      
General, administrative and other expenses   2,382 2,463 6,942 6,986      
Loss from operations   (3,689) (7,210) (18,457) (14,542)      
Gain on settlements with former operator   0 0 0 17,440      
Net income (loss)   (3,689) (7,210) (18,457) 2,898      
Depreciation and amortization   6,200 3,200 16,900 8,600      
Net income (loss) before depreciation and amortization   2,525 (4,021) (1,577) 11,504      
Financial Position [Abstract]                
Current assets   22,839   22,839   22,860    
Noncurrent assets   247,335   247,335   251,741    
Total assets   270,174   270,174   274,601    
Current liabilities   26,315   26,315   8,005    
Long term liabilities   78,265   78,265   82,546    
Shareholders' equity   165,594   165,594   184,050    
Total liabilities and Shareholders' equity   270,174   270,174   $ 274,601    
Equity in Income or Loss of AMAK Reflected on Consolidated Statement Of Operation [Abstract]                
AMAK Net income (loss)   (3,689) (7,210) (18,457) 2,898      
Zakat tax applicable to Saudi Arabian shareholders only   0 0 0 320      
AMAK Net Income (Loss) before Saudi Arabian shareholders' portion of Zakat   (3,689) (7,210) (18,457) 3,218      
Company's share of income (loss) reported by AMAK   (1,234) (2,426) (6,172) 1,250      
Amortization of difference between Company's investment in AMAK and Company's share of net assets of AMAK   337 337 1,011 1,011      
Equity in earnings (loss) of AMAK   $ (897) $ (2,089) $ (5,161) $ 2,261      
Arab Mining Co [Member]                
Schedule of Equity Method Investments [Line Items]                
Shares issued (in shares) | shares 3,750,000              
Share price (in dollars per share) | (per share) $ 5.33           SAR 20.00  
Shares reserved for future issuance (in shares) | shares 250,000           250,000