DEFERRED REVENUE AND COSTS (DEFERRED REVENUE CLASSIFICATION TABLE) (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
DEFERRED REVENUE AND COSTS [ABSTRACT]
Deferred revenue - current	$ 39,447	$ 44,926
Deferred revenue - long-term	23,142	33,247
Total deferred revenue	$ 62,589	$ 78,173