Common Stock - Summary of Share-Based Compensation Expense for Stock Options and Restricted Stock (Detail) - USD ($) $ in Thousands |
3 Months Ended | 9 Months Ended | ||
---|---|---|---|---|
Sep. 30, 2018 |
Sep. 30, 2017 |
Sep. 30, 2018 |
Sep. 30, 2017 |
|
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items] | ||||
Total stock-based compensation | $ 210 | $ 152 | $ 588 | $ 152 |
Research and development [Member] | ||||
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items] | ||||
Total stock-based compensation | 70 | 43 | 190 | 43 |
General and administrative [Member] | ||||
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items] | ||||
Total stock-based compensation | $ 140 | $ 109 | $ 398 | $ 109 |