FAIR VALUE OF FINANCIAL INSTRUMENTS - Continuous Loss Position (Details)
$ in Thousands
Jun. 30, 2019
USD ($)
Fair Value of marketable securities  
Fair value of marketable securities, continuous unrealized losses, less than 12 months $ 8,072
Fair value of marketable securities, continuous unrealized losses, 12 months or greater 0
Fair value of marketable securities, continuous unrealized losses 8,072
Unrealized Loss  
Unrealized loss, continuous unrealized losses, less than 12 months (3)
Unrealized loss, continuous unrealized losses, 12 months or greater 0
Unrealized loss, continuous unrealized losses $ (3)