STOCKHOLDERS' EQUITY, STOCK-BASED COMPENSATION AND NET LOSS PER SHARE - Unrecognized Share-based Compensation (Details) $ in Thousands |
12 Months Ended |
|---|---|
|
Dec. 31, 2019
USD ($)
| |
| Stock options | |
| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | |
| Unrecognized share-based compensation cost for non-vested awards (in thousands): | $ 191 |
| Weighted-average years over which unrecognized share-based compensation expense will be recognized: | 1 year 1 month 6 days |
| China | |
| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | |
| Unrecognized share-based compensation cost for non-vested awards (in thousands): | $ 5 |
| Weighted-average years over which unrecognized share-based compensation expense will be recognized: | 6 days |