LEASES AND RIGHT OF USE ASSETS - Supplemental Balance Sheet Information (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Operating leases:
Operating leases - right of use assets	$ 12,077
Current operating lease obligations	7,556
Long-term operating lease obligations	4,568
Total operating lease liabilities	12,124
Finance leases:
Property and equipment, at cost	358,738	$ 341,151
Accumulated amortization	(116,698)	(115,766)
Property and equipment, net	242,040	$ 225,385
Current finance lease obligations	19,469
Long-term finance lease obligations	68,610
Total lease obligations	$ 88,079
Weighted average remaining lease term:
Operating leases	41 months
Finance leases	45 months
Weighted average discount rate:
Operating leases	4.07%
Finance leases	3.37%
Equipment finance leases
Finance leases:
Property and equipment, at cost	$ 127,798
Accumulated amortization	(27,851)
Property and equipment, net	$ 99,947