ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Schedule of Cash, Cash Equivalents, and Restricted Cash (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019	Jun. 30, 2019	Dec. 31, 2018
Cash And Cash Equivalents, Resticted Cash And Restricted Cash Equivalents [Roll Forward]
Cash and cash equivalents	$ 20,712	$ 24,762		$ 21,845
Restricted Cash and Cash Equivalents, Current	943	943		1,514
Restricted Cash and Cash Equivalents, Noncurrent	4,242	5,295		7,225
Cash, cash equivalents and restricted cash	$ 25,897	$ 31,000	$ 31,770	$ 30,584