Stockholders' Equity (Stock-based Compensation Expense) (Details) - USD ($) $ in Thousands |
3 Months Ended | |
|---|---|---|
Mar. 31, 2021 |
Mar. 31, 2020 |
|
| Share-based Compensation | $ 996 | $ 805 |
| General and Administrative [Member] | ||
| Share-based Compensation | 324 | 352 |
| Research and Development [Member] | ||
| Share-based Compensation | $ 672 | $ 453 |
| X | ||||||||||
- Definition Amount of noncash expense for share-based payment arrangement. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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| X | ||||||||||
- Details
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| X | ||||||||||
- Details
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