ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Schedule of Cash, Cash Equivalents, and Restricted Cash (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020	Jun. 30, 2020	Dec. 31, 2019
Cash And Cash Equivalents, Resticted Cash And Restricted Cash Equivalents [Roll Forward]
Cash and cash equivalents	$ 25,967	$ 22,207		$ 24,762
Restricted Cash and Cash Equivalents, Current	944	944		943
Restricted Cash and Cash Equivalents, Noncurrent	1,179	4,346		5,295
Cash, cash equivalents and restricted cash	$ 28,090	$ 27,497	$ 25,897	$ 31,000