ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Loyalty Program Rollforward (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Movement in Deferred Revenue [Roll Forward]
Loyalty program deferred revenue, beginning balance	$ 4,231	$ 6,406
Loyalty points forfeited or expired	(4,348)	(4,332)
Loyalty points used	(9,127)	(11,398)
Loyalty points vested	11,320	12,469
Loyalty points unvested	1,051	1,086
Loyalty program deferred revenue, ending balance	$ 3,127	$ 4,231