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Stock-Based Compensation - Schedule of Assumptions Used to Determine Fair Value of Options Granted (Details)
3 Months Ended
Mar. 31, 2019
Mar. 31, 2018
Risk-free interest rate 2.65% 2.82%
Expected volatility   99.90%
Expected life (in years)   10 years
Expected dividend yield 0.00% 0.00%
Minimum [Member]    
Expected volatility 101.30%  
Expected life (in years) 7 years 6 months  
Maximum [Member]    
Expected volatility 106.20%  
Expected life (in years) 9 years 3 months 19 days