SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES AND ESTIMATES - Summary of accrued liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Accounting Policies [Abstract]
Accrued drilling, completion and facilities costs	$ 2,163	$ 5,021
Drilling advances	1,372	1,328
Accrued production expenses	2,037	3,326
Other accrued liabilities	4,409	3,885
Short-term operating lease liabilities	829	412
Total accrued liabilities	$ 10,810	$ 13,972