OPERATING LEASE - Operating lease costs (Details) $ in Thousands		6 Months Ended
	Mar. 13, 2019 USD ($) ft²	Jun. 30, 2020 USD ($)	Dec. 31, 2019 USD ($)
Operating Lease
Operating lease right-of-use assets		$ 2,558	$ 1,694
Total lease liability		$ 2,553
Operating lease terms		3 years
Vehicles lease prepaid period		3 months
Lien on marketable securities to secure lease agreements		$ 700
Building [Member] | Redwood City, California
Operating Lease
Monthly base rent		$ 60
Original Space | Bridgewater, New Jersey
Operating Lease
Facility space leased | ft²	10,000
Operating lease right-of-use assets	$ 700
Additional Space | Bridgewater, New Jersey
Operating Lease
Facility space leased | ft²	4,639
Operating lease right-of-use assets	$ 300