REVENUES (Contract Balances) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Change in Contract with Customer, Asset and Liability [Abstract]
Revenues from performance obligations satisfied in previous period	$ 4,915	$ 3,610	$ 7,039	$ 6,627
Change in Contract with Customer, Liability [Abstract]
Revenue recognized	140		3,801
Unbilled revenues	24,870		24,870		$ 13,522
Accrued expenses and other current liabilities
Change in Contract with Customer, Liability [Abstract]
Deferred revenues	4,954		4,954		4,558
Other noncurrent liabilities
Change in Contract with Customer, Liability [Abstract]
Deferred revenues	$ 1		$ 1		$ 224