ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Loyalty Program Rollforward (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Movement in Deferred Revenue [Roll Forward]
Loyalty program deferred revenue, beginning balance	$ 3,127	$ 4,231
Loyalty points forfeited or expired	(3,249)	(4,348)
Loyalty points used	(9,385)	(9,127)
Loyalty points vested	12,771	11,320
Loyalty points unvested	1,223	1,051
Loyalty program deferred revenue, ending balance	$ 4,487	$ 3,127