REVENUES (Contract Balances) (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2018	Dec. 31, 2017
Schedule of Contract Balances [Line Items]
Unbilled revenues	$ 18,393	$ 18,393	$ 7,901
Change in Contract with Customer, Liability [Abstract]
Revenue recognized that was previously included in deferred revenues	1,808	3,432
Revenues from performance obligations satisfied in previous periods	5,452	6,618
Accrued expenses and other current liabilities
Schedule of Contract Balances [Line Items]
Deferred revenues	$ 5,398	$ 5,398	$ 4,498