Quarterly report pursuant to Section 13 or 15(d)

Stock-based Compensation - Stock-based Compensation Expense (Details)

v3.19.1
Stock-based Compensation - Stock-based Compensation Expense (Details) - USD ($)
$ in Thousands
3 Months Ended
Mar. 31, 2019
Mar. 31, 2018
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]    
Total stock-based compensation expense $ 1,728 $ 1,416
Research and Development [Member]    
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]    
Total stock-based compensation expense 49 104
General and Administrative [Member]    
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]    
Total stock-based compensation expense $ 1,679 $ 1,312