FAIR VALUE DISCLOSURES - Warrant Liabilities (Details) - $ / shares |
Dec. 31, 2020 |
Dec. 31, 2019 |
|---|---|---|
| Class of Warrant or Right [Line Items] | ||
| Exercise price of warrants | $ 11.50 | |
| Warrants term | 4 years | |
| Series D preferred warrants | ||
| Class of Warrant or Right [Line Items] | ||
| Exercise price of warrants | $ 0.01 | $ 6.58 |
| Outstanding warrants | ||
| Class of Warrant or Right [Line Items] | ||
| Exercise price of warrants | $ 6.58 |