Common Stock - Summary of Share-Based Compensation Expense for Stock Options and Restricted Stock (Detail) - USD ($) $ in Thousands |
3 Months Ended | 9 Months Ended | ||
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Sep. 30, 2019 |
Sep. 30, 2018 |
Sep. 30, 2019 |
Sep. 30, 2018 |
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| Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items] | ||||
| Total stock-based compensation | $ 310 | $ 210 | $ 917 | $ 588 |
| Research and development [Member] | ||||
| Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items] | ||||
| Total stock-based compensation | 89 | 70 | 275 | 190 |
| General and administrative [Member] | ||||
| Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items] | ||||
| Total stock-based compensation | $ 221 | $ 140 | $ 642 | $ 398 |
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. No definition available.
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- Definition Amount of noncash expense for share-based payment arrangement. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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