Stockholders' Equity (Stock-based Compensation Expense) (Details) - USD ($) $ in Thousands |
3 Months Ended | 9 Months Ended | ||
|---|---|---|---|---|
Sep. 30, 2021 |
Sep. 30, 2020 |
Sep. 30, 2021 |
Sep. 30, 2020 |
|
| Share-based Compensation | $ 884 | $ 606 | $ 2,427 | $ 2,368 |
| General and Administrative [Member] | ||||
| Share-based Compensation | 229 | 348 | 793 | 1,213 |
| Research and Development [Member] | ||||
| Share-based Compensation | $ 655 | $ 258 | $ 1,634 | $ 1,155 |
| X | ||||||||||
- Definition Amount of noncash expense for share-based payment arrangement. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
|
| X | ||||||||||
- Details
|
| X | ||||||||||
- Details
|