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STOCK OPTIONS, ASSUMPTIONS USED IN DETERMINING THE FAIR VALUE (Details) - Stock Options
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Assumptions used principally in determining the fair value of options granted      
Expected dividend yield (as a percent) 0.00% 0.00% 0.00%
Expected term (employee grants) 6 years 2 months 19 days 5 years 11 months 27 days 6 years
Expected volatility (as a percent) 104.00% 111.00% 116.00%
Minimum      
Assumptions used principally in determining the fair value of options granted      
Risk-free interest rate (as a percent) 1.69% 1.20% 1.53%
Maximum      
Assumptions used principally in determining the fair value of options granted      
Risk-free interest rate (as a percent) 2.36% 1.52% 1.89%