REVENUES (Reconciliation of Deferred Revenue Balances) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
REVENUES [Abstract]
Balance at beginning of period	$ 181,963	$ 189,052	$ 185,339	$ 192,783
Revenue recognized from deferred revenue	(2,046)	(2,125)	(5,422)	(5,856)
Balance at end of period	$ 179,917	$ 186,927	$ 179,917	$ 186,927