DERIVATIVE INSTRUMENTS (Details) - USD ($) $ in Thousands	1 Months Ended			3 Months Ended			12 Months Ended
	Sep. 30, 2018	Jun. 30, 2018	May 31, 2018	Mar. 31, 2019	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2018	Dec. 31, 2017
Derivative instruments
Derivative warrant liability						$ 2		$ 4
Number of warrants outstanding				7,673,130
Fair value adjustment of warrants						$ (12)
Underwritten Public Offering, June 2018
Derivative instruments
Proceeds allocated to warrant liability		$ 13,200
Amount recorded to permanent equity		287
Derivative warrant liability		25,200			$ 25,200
Derivative loss					$ 12,000
Reclassification of derivative warrant liability to additional paid-in capital		$ 287
2018 Series A Warrant Exercise price $2.00
Derivative instruments
Number of warrants outstanding				7,586,711
2018 Series A Warrant Exercise price $2.00 | Underwritten Public Offering, June 2018
Derivative instruments
Proceeds from exercise of warrants							$ 69
Number of warrants outstanding				0
2018 Series B Warrant Exercise price $.01 | Underwritten Public Offering, June 2018
Derivative instruments
Amount recorded to permanent equity				$ 10,600
Derivative loss				$ 1,200			1,200
Proceeds from exercise of warrants							$ 62
Number of warrants outstanding				0			0
Reclassification of derivative warrant liability to additional paid-in capital				$ 10,600
2014 Warrant Exercise price $11.75
Derivative instruments
Number of warrants outstanding				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
2018 Warrants | Underwritten Public Offering, June 2018
Derivative instruments
Proceeds from exercise of warrants							$ 131
Common Stock | 2018 Series A Warrant Exercise price $2.00 | Underwritten Public Offering, June 2018
Derivative instruments
Issuance of common stock upon exercise of warrants (in shares)							34,500
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)							6,242,811