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CONCENTRATION OF RISK - Additional Information (Details) - supplier
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Supplier Concentration Risk [Member]      
Concentration Risk [Line Items]      
Number of suppliers from which chemical materials were purchased 1    
Excluding North America [Member] | Total Revenue [Member] | Customer Concentration Risk [Member]      
Concentration Risk [Line Items]      
Concentration risk, percentage (less than 1% for contracts with U.S. government agencies) 97.00% 98.00% 99.00%