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Employee Stock Options (Details) - Employee Stock Option [Member]
12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Summary of assumptions used to estimate fair value of stock options granted    
Expected dividend yield 0.00% 0.00%
Expected life of options 4 years  
Minimum [Member]    
Summary of assumptions used to estimate fair value of stock options granted    
Expected volatility 80.00% 82.00%
Risk-free interest rate 2.41% 1.50%
Expected life of options   2 years 6 months
Maximum [Member]    
Summary of assumptions used to estimate fair value of stock options granted    
Expected volatility 96.00% 101.00%
Risk-free interest rate 2.93% 2.62%
Expected life of options   4 years