LEASES - Components of expense and supplemental cash flow information (Details) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)
Operating
Fixed operating lease expense	$ 6,439	$ 13,296
Variable operating lease expense	3,299	6,351
Total operating lease expense	9,738	19,647
Cash paid for amounts included in the measurement of operating lease liabilities		7,820
ROU assets obtained in exchange for operating lease obligations		0
Finance
Amortization of right of use assets	3,920	7,834
Interest expense	495	1,050
Total finance lease expense	$ 4,415	$ 8,884
Weighted average remaining lease term (in years)	1 year 9 months 25 days	1 year 9 months 25 days
Weighted average discount rate	5.38%	5.38%