Stockholders' Equity (Stock-Based Compensation Expense Allocation) (Details) - USD ($) $ in Thousands |
3 Months Ended | 9 Months Ended | ||
|---|---|---|---|---|
Sep. 30, 2022 |
Sep. 30, 2021 |
Sep. 30, 2022 |
Sep. 30, 2021 |
|
| Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items] | ||||
| Stock-based compensation expenses | $ 360 | $ 807 | $ 1,780 | $ 2,252 |
| Research and development | ||||
| Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items] | ||||
| Stock-based compensation expenses | 56 | 277 | 425 | 687 |
| General and administrative | ||||
| Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items] | ||||
| Stock-based compensation expenses | $ 304 | $ 530 | $ 1,355 | $ 1,565 |