DERIVATIVE INSTRUMENTS (Details) - USD ($) $ in Thousands	1 Months Ended			3 Months Ended			9 Months Ended
	Sep. 30, 2018	Jun. 30, 2018	May 31, 2018	Sep. 30, 2019	Sep. 30, 2018	Jun. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018	Dec. 31, 2017
Derivative instruments
Derivative warrant liability		$ 21,469				$ 21,469				$ 4
Proceeds from exercise of warrants								$ 55
Number of warrants outstanding				7,673,130			7,673,130
Fair value adjustment of warrants					$ (1,967)			(12,165)
Warrant reclassified to equity					(14,706)			(14,707)
Underwritten Public Offering, June 2018
Derivative instruments
Proceeds allocated to warrant liability		13,200
Amount recorded to permanent equity		286
Derivative warrant liability		25,200				25,200
Derivative loss						$ 12,000
Reclassification of derivative warrant liability to additional paid-in capital		$ 286
2018 Series A Warrant Exercise price $2.00
Derivative instruments
Number of warrants outstanding				7,586,711			7,586,711
2018 Series B Warrant Exercise price $.01 | Underwritten Public Offering, June 2018
Derivative instruments
Amount recorded to permanent equity					8,700			10,600
Derivative loss					1,200			1,200
Proceeds from exercise of warrants					44			55
Number of warrants outstanding				0			0		0
Reclassification of derivative warrant liability to additional paid-in capital					$ 8,700			$ 10,600
2014 Warrant Exercise price $11.75
Derivative instruments
Number of warrants outstanding				307			307
Fair value adjustment of warrants			$ 1
Warrant reclassified to equity			$ 1
2018 Warrants
Derivative instruments
Fair value adjustment of warrants	$ 764
Warrant reclassified to equity	$ 14,700
Common Stock | 2018 Series B Warrant Exercise price $.01 | Underwritten Public Offering, June 2018
Derivative instruments
Issuance of common stock upon exercise of warrants (in shares)				0	4,427,084		0	5,478,002