LEASES - Lease Costs (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Leases [Abstract]
Operating lease expense	$ 4,134		$ 11,064
Short-term lease expense	119		765
Sublease income	(192)		(734)
Operating lease expense	4,061	$ 8,000	11,095	$ 14,000
Operating cash outflows from operating leases	6,384		12,920
Right-of-use assets obtained in exchange for new operating lease liabilities	$ 0		$ 0
Weighted-average remaining lease term - operating leases	8 years 8 months 12 days		8 years 8 months 12 days
Weighted-average discount rate - operating lease	4.70%		4.70%