OTHER NON-CURRENT ASSETS (Changes in Deferred Contract Costs) (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2018 USD ($)
Changes In Capitalized Contract Costs [Roll Forward]
Balance, beginning of period	$ 9,089
Less: amortization recorded in sales and marketing expense	(2,535)
Add: costs deferred on new contracts	3,129
Balance, end of period	$ 9,683