DEFERRED REVENUE AND COSTS (DEFERRED COSTS CLASSIFICATION TABLE) (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
DEFERRED REVENUE AND COSTS [ABSTRACT]
Deferred Costs - Current	$ 25,669	$ 26,092
Deferred Costs - Long-term	18,015	25,436
Total Deferred Costs	$ 43,684	$ 51,528