Quarterly report pursuant to Section 13 or 15(d)

INVESTMENT IN AMAK - Additional Information (Details)

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INVESTMENT IN AMAK - Additional Information (Details)
$ in Thousands
3 Months Ended
Mar. 31, 2018
shares
Jun. 30, 2018
USD ($)
ر.س / $
Mar. 30, 2018
Dec. 31, 2017
USD ($)
Treasury Stock [Member]        
Schedule of Equity Method Investments [Line Items]        
Number of stock exchanged (in shares) | shares 65,000      
AMAK [Member]        
Schedule of Equity Method Investments [Line Items]        
Number of stock exchanged (in shares) | shares 24,489      
Percentage investment in equity method investment 33.41% 33.40% 33.44% 33.40%
Investment in equity method investment | $   $ 45,500   $ 45,100
Exchange rate | ر.س / $   3.75    
Amount receivable for unreimbursed travel expenses | $   $ 204   $ 121