REVENUE RECOGNITION - Schedule of Effect of New Accounting Pronouncements (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Jan. 01, 2018	Dec. 31, 2017
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Prepaid expenses and other current assets	$ 548,000		$ 548,000		$ 603,000	$ 536,000
Deferred revenue, current	240,000		240,000		146,000	143,000
Accumulated deficit	(79,416,000)		(79,416,000)		$ (67,748,000)	(67,812,000)
Revenue	124,000	$ 220,000	281,000	$ 376,000
Net loss	(5,952,000)	$ (4,263,000)	(11,668,000)	$ (9,157,000)
Calculated under Revenue Guidance in Effect before Topic 606
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Prepaid expenses and other current assets	521,000		521,000			536,000
Deferred revenue, current	229,000		229,000			143,000
Accumulated deficit	(79,432,000)		(79,432,000)			(67,812,000)
Revenue	125,000		330,000
Net loss	(5,951,000)		(11,619,000)
Accounting Standards Update 2014-09 | Difference between Revenue Guidance in Effect before and after Topic 606
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Prepaid expenses and other current assets	27,000		27,000			67,000
Deferred revenue, current	11,000		11,000			3,000
Accumulated deficit	16,000		16,000			$ 64,000
Revenue	(1,000)		(49,000)
Net loss	$ 1,000		$ 49,000