LEASES - Components of expense and supplemental cash flow information (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2019 USD ($)
Operating
Fixed operating lease expense	$ 6,857
Variable operating lease expense	3,052
Total operating lease expense	9,909
Cash paid for amounts included in the measurement of operating lease liabilities	3,881
ROU assets obtained in exchange for operating lease obligations	0
Finance
Amortization of right of use assets	3,914
Interest expense	555
Total finance lease expense	$ 4,469
Weighted average remaining lease term (in years)	2 years 22 days
Weighted average discount rate	5.38%