Quarterly report pursuant to Section 13 or 15(d)

Share-Based Compensation - Schedule of Assumptions Used to Determine Grant Date Fair Value of Employee and Director Options Granted (Details)

v3.19.1
Share-Based Compensation - Schedule of Assumptions Used to Determine Grant Date Fair Value of Employee and Director Options Granted (Details) - $ / shares
3 Months Ended
Mar. 31, 2019
Mar. 31, 2018
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]    
Volatility   60.00%
Volatility, minimum 69.50%  
Volatility, maximum 70.20%  
Expected term in years 6 years 3 months 6 years 3 months
Dividend rate 0.00% 0.00%
Risk-free interest rate   1.63%
Risk-free interest rate, minimum 2.44%  
Risk-free interest rate, maximum 2.57%  
Minimum    
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]    
Share price $ 5.80  
Fair value of option on grant date 3.74  
Maximum    
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]    
Share price 6.80  
Fair value of option on grant date $ 4.41