LEASES - Components of lease costs and other information (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2020 USD ($)
Lease, Cost [Abstract]
Fixed lease costs	$ 265
Short-term lease costs	218
Variable lease costs	84
Sublease income	(22)
Total lease costs	545
Lessee, Lease, Description [Line Items]
Total lease costs	545
Cash paid for amounts included in the measurement of operating lease liabilities:
Operating cash flows from operating leases	262
Investing cash flows from operating leases	$ 0
Lease term and discount rate
Weighted-average remaining lease term (years)	3 years 6 months 11 days
Weighted-average discount rate	5.31%
General and administrative
Lease, Cost [Abstract]
Total lease costs	$ 175
Lessee, Lease, Description [Line Items]
Total lease costs	175
Total lease costs expensed
Lease, Cost [Abstract]
Total lease costs	545
Lessee, Lease, Description [Line Items]
Total lease costs	545
Sublease income
Lease, Cost [Abstract]
Total lease costs	22
Lessee, Lease, Description [Line Items]
Total lease costs	22
Oil sales | Production costs
Lease, Cost [Abstract]
Total lease costs	370
Lessee, Lease, Description [Line Items]
Total lease costs	$ 370