SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Schedule of Cash) (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
Cash and cash equivalents	$ 100,143	$ 40,087	$ 20,538
Restricted cash	27,781	6,987	2,503
Total cash, cash equivalents, and restricted cash	$ 127,924	$ 47,074	$ 23,041	$ 5,595