DEFERRED REVENUE AND COSTS (DEFERRED COSTS CLASSIFICATION TABLE) (DETAILS) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
DEFERRED REVENUE AND COSTS [ABSTRACT]
Deferred costs - current	$ 13,649	$ 14,755
Deferred costs - long-term	9,654	8,124
Total deferred costs	$ 23,303	$ 22,879