ACCOUNTING FOR LEASES - Lease costs (Details) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2019 USD ($)	Sep. 30, 2019 USD ($)
ACCOUNTING FOR LEASES
Short-term lease costs	$ 82	$ 258
Long-term lease costs	372	1,114
Total lease costs	$ 454	$ 1,372
Weighted-average incremental borrowing rate of operating leases	4.33%	4.33%