ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Other Long-Term Liabilities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Other long-term liabilities	$ 7,245	$ 6,214
Uncertain income tax positions recorded in noncurrent liabilities	200	200
Accrued lease restoration costs	300	300
Severance Costs	500	400
Accrued benefit liability	370	319
Operating Lease, Liability, Noncurrent	6,100	5,300
Foreign Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Accrued benefit liability	$ 400	$ 300