ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Cash and Cash Equivalents (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents	$ 24,185	$ 22,207	$ 24,762
Credit card receivables	1,200	2,400
Cash and cash equivalents held in bank accounts in foreign countries	22,600	18,600
Restricted Cash, Current	944	944	943
Restricted Cash, Noncurrent	503	4,346	5,295
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	25,632	$ 27,497	$ 31,000
South Korea
Cash and Cash Equivalents [Line Items]
Net assets	$ 20,100