REVENUES (Reconciliation of Deferred Revenue Balances) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
REVENUES [Abstract]
Balance at beginning of year	$ 185,339	$ 192,783
Revenue recognized from deferred revenue	(1,342)	(1,652)
Balance at end of period	$ 183,997	$ 191,131