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BASIS OF PRESENTATION AND CERTAIN SIGNIFICANT ACCOUNTING POLICIES, Short Term Investments (Details) - USD ($)
$ in Thousands
6 Months Ended 12 Months Ended
Jun. 30, 2020
Jun. 30, 2019
Dec. 31, 2019
Short-term Investments [Abstract]      
Payments to acquire short-term investments $ 1,697 $ 10,679  
US Treasuries [Member]      
Short-term Investments [Abstract]      
Payments to acquire short-term investments $ 4,600   $ 9,200