LEASES - Components of lease costs and other information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Lessee Lease Description [Line Items]
Fixed lease costs	$ 76	$ 1,249	$ 519	$ 4,085
Short-term lease costs	47	120	382	329
Variable lease costs	12	508	180	626
Sublease income	(4)		(49)
Total lease costs	131	1,877	1,032	5,040
Total lease costs	$ 131	$ 1,877	1,032	$ 5,040
Cash paid for amounts included in the measurement of operating lease liabilities:
Operating cash flows from operating leases			$ 906
Lease term and discount rate
Weighted-average remaining lease term (years)	2 years 9 months 29 days		2 years 9 months 29 days
Weighted-average discount rate	6.69%		6.69%
General and Administrative Expense
Lessee Lease Description [Line Items]
Total lease costs			$ 459
Total lease costs			459
Operating Expense
Lessee Lease Description [Line Items]
Total lease costs			1,081
Total lease costs			1,081
Sublease Income
Lessee Lease Description [Line Items]
Sublease income			(49)
Oil Sales [Member] | Production costs
Lessee Lease Description [Line Items]
Total lease costs			622
Total lease costs			$ 622