Stock Plans - Stock-based compensation expense and impact (Details) - USD ($) $ in Thousands |
12 Months Ended | |
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Dec. 31, 2019 |
Dec. 31, 2018 |
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| Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost | ||
| Total stock-based compensation expense | $ 572 | $ 1,557 |
| Research and development | ||
| Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost | ||
| Total stock-based compensation expense | 91 | 575 |
| General and administrative | ||
| Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost | ||
| Total stock-based compensation expense | $ 481 | $ 982 |
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- Definition Amount of expense for award under share-based payment arrangement. Excludes amount capitalized. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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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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