REVENUES (Contract Balances) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Change in Contract with Customer, Asset and Liability [Abstract]
Revenues from performance obligations satisfied in previous period	$ 7,693	$ 5,452	$ 4,119	$ 6,618
Change in Contract with Customer, Liability [Abstract]
Revenue recognized	610		3,661
Unbilled revenues	23,381		23,381		$ 13,522
Accrued expenses and other current liabilities
Change in Contract with Customer, Liability [Abstract]
Deferred revenues	6,321		6,321		4,558
Other noncurrent liabilities
Change in Contract with Customer, Liability [Abstract]
Deferred revenues	$ 3		$ 3		$ 224