LEASES - Supplemental Balance Sheet Information (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Operating leases:
Operating leases - right of use assets	$ 9,830	$ 11,775
Current operating lease obligations	4,602	6,050
Long-term operating lease obligations	5,347	5,812
Total operating lease liabilities	9,949	11,862
Finance leases:
Property and equipment, at cost	381,717	372,885
Accumulated amortization	(133,808)	(124,216)
Property and equipment, net	247,909	248,669
Current finance lease obligations	29,363	30,779
Long-term finance lease obligations	56,847	58,397
Total lease obligations	$ 86,210	$ 89,176
Weighted average remaining lease term:
Operating leases	47 months	45 months
Finance leases	41 months	44 months
Weighted average discount rate:
Operating leases	4.02%	4.03%
Finance leases	3.34%	3.34%
Equipment finance leases
Finance leases:
Property and equipment, at cost	$ 121,421	$ 120,236
Accumulated amortization	(35,464)	(30,990)
Property and equipment, net	$ 85,957	$ 89,246