XML 37 R27.htm IDEA: XBRL DOCUMENT v3.19.2
Summary of Significant Accounting Policies - Stock-Based Compensation (Details) - USD ($)
$ in Thousands
3 Months Ended 6 Months Ended
Jun. 30, 2019
Jun. 30, 2018
Jun. 30, 2019
Jun. 30, 2018
Stock-Based Compensation        
Stock-based compensation expense $ 441 $ 446 $ 849 $ 924
Research and development        
Stock-Based Compensation        
Stock-based compensation expense 165 164 300 337
General and administrative        
Stock-Based Compensation        
Stock-based compensation expense $ 276 $ 282 $ 549 $ 587