SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Significant accounting judgments and estimates (Details) |
12 Months Ended |
|---|---|
Dec. 31, 2020 | |
| Bottom of range | |
| Disclosure of quantitative information about right-of-use assets [line items] | |
| Weighted average lessee's incremental borrowing rate applied to lease liabilities | 9.80% |
| Top of range | |
| Disclosure of quantitative information about right-of-use assets [line items] | |
| Weighted average lessee's incremental borrowing rate applied to lease liabilities | 15.00% |