Prepaid Expenses and Other Current Assets (Schedule of Prepaid Expenses and Other Current Assets) (Details) - USD ($) $ in Thousands |
Dec. 31, 2021 |
Dec. 31, 2020 |
|---|---|---|
| Prepaid Expenses and Other Current Assets [Abstract] | ||
| Vendor prepayments | $ 471 | $ 716 |
| Other prepaid expenses | 220 | 227 |
| Total prepaid expenses and other current assets | $ 691 | $ 943 |