Quarterly report pursuant to Section 13 or 15(d)

Stock Based Compensation - Schedule of Stock-Based Compensation Expense (Details)

v3.8.0.1
Stock Based Compensation - Schedule of Stock-Based Compensation Expense (Details) - USD ($)
$ in Thousands
3 Months Ended
Mar. 31, 2018
Mar. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]    
Share-based compensation expense $ 1,748 $ 1,372
Research and Development [Member]    
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]    
Share-based compensation expense 573 435
General and Administrative [Member]    
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]    
Share-based compensation expense $ 1,175 $ 937