XML 17 R51.htm IDEA: XBRL DOCUMENT v3.19.3
Stock-Based Compensation - Schedule of Assumptions Used to Determine Fair Value of Options Granted (Details)
9 Months Ended
Sep. 30, 2019
Sep. 30, 2018
Risk-free interest rate, minimum 1.69% 2.82%
Risk-free interest rate, maximum 2.65% 3.02%
Expected volatility, minimum 101.30% 99.90%
Expected volatility, maximum 106.20% 102.10%
Expected dividend yield 0.00% 0.00%
Minimum [Member]    
Expected life (in years) 6 years 6 months 8 years
Maximum [Member]    
Expected life (in years) 9 years 2 months 12 days 10 years