Quarterly report pursuant to Section 13 or 15(d)

Stock-based Compensation - Schedule of Share Based Payment Assumptions (Details)

v3.19.1
Stock-based Compensation - Schedule of Share Based Payment Assumptions (Details)
3 Months Ended
Mar. 31, 2019
Mar. 31, 2018
Share-based Payment Arrangement [Abstract]    
Volatility, minimum 110.85% 105.85%
Volatility, maximum 111.34% 107.95%
Risk-free interest rate, minimum 2.46% 2.29%
Risk-free interest rate, maximum 2.65% 2.71%
Dividend yield 0.00% 0.00%
Expected life 6 years 6 years