LEASES - Components of Lease Expense and Payments (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
LEASES
Operating lease cost	$ 4,047	$ 3,516
Short-term lease cost	543	713
Variable lease cost	803	961
Total operating lease cost	5,393	5,190
Payments for lease liabilities	3,500	3,200
Lease liabilities arising from right-of-use assets	0	200
Finance lease cost:
Amortization of right-of-use asset	571	593
Variable costs	272	296
Total finance lease cost	843	$ 889
Finance leases cost included in property, plant and equipment	$ 26,300		$ 25,900
Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	us-gaap:PropertyPlantAndEquipmentGross		us-gaap:PropertyPlantAndEquipmentGross
Accumulated depreciation related to finance leases	$ 10,000		$ 9,400