ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Sales Returns (Details) - Allowance for Sales Returns - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Sales reserves, beginning balance	$ 71	$ 68
Provision related to sales made in current period	262	1,028
Adjustment related to sales made in prior periods	(14)	5
Actual returns or credits related to current period	(179)	(959)
Actual returns or credits related to prior periods	(54)	(71)
Sales reserves, ending balance	$ 86	$ 71