SUBSEQUENT EVENT - Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands		1 Months Ended	3 Months Ended				9 Months Ended
	Oct. 28, 2019	Oct. 31, 2019	Jun. 30, 2019	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2019	Sep. 30, 2018	Oct. 27, 2019	Dec. 31, 2018	Nov. 30, 2017
Subsequent Event [Line Items]
Number of warrants issued (in shares)			20,400,000			8,000,000
Exercise price per warrant (in dollars per share)			$ 1.47			$ 1.20
Warrants remaining outstanding (in shares)							26,307,000			9,258,000
Proceeds from exercises of common stock warrants							$ 3,434	$ 7,315
Exercise of stock warrants (in shares)							3,361,000
2017 Warrants
Subsequent Event [Line Items]
Exercise price per warrant (in dollars per share)							$ 0.80
Warrants remaining outstanding (in shares)							492,000			1,992,000
Exercise of stock warrants (in shares)							1,500,000
2018 Warrants
Subsequent Event [Line Items]
Exercise price per warrant (in dollars per share)							$ 1.20
Warrants remaining outstanding (in shares)							5,350,000			7,211,000
Exercise of stock warrants (in shares)							1,861,000
Common Stock
Subsequent Event [Line Items]
Exercise of stock warrants (in shares)			3,361,115	50,000	8,294,718	420,778	3,400,000	8,700,000
Common Stock | 2017 Warrants
Subsequent Event [Line Items]
Number of warrants issued (in shares)											10,000,000
Exercise price per warrant (in dollars per share)											$ 0.80
Warrants remaining outstanding (in shares)											500,000
Subsequent Event
Subsequent Event [Line Items]
Warrants remaining outstanding (in shares)		22,895,000
Exercise of stock warrants (in shares)		3,412,000
Subsequent Event | 2017 Warrants
Subsequent Event [Line Items]
Exercise price per warrant (in dollars per share)		$ 0.55
Warrants remaining outstanding (in shares)		487,000
Exercise of stock warrants (in shares)		5,000
Subsequent Event | 2018 Warrants
Subsequent Event [Line Items]
Exercise price per warrant (in dollars per share)		$ 0.95
Warrants remaining outstanding (in shares)		1,943,000
Exercise of stock warrants (in shares)		3,407,000
Subsequent Event | 2018 Warrant Amendment, Amendment to Securities Purchase Agreement
Subsequent Event [Line Items]
Minimum percentage of securities issued	50.10%
Subsequent Event | Common Stock | 2017 Warrants
Subsequent Event [Line Items]
Exercise price per warrant (in dollars per share)	$ 0.55	$ 0.55							$ 0.80
Subsequent Event | Common Stock | 2018 Warrants
Subsequent Event [Line Items]
Exercise price per warrant (in dollars per share)	$ 0.60	$ 0.95							$ 1.20
Proceeds from exercises of common stock warrants	$ 2,000
Exercise of stock warrants (in shares)	3,400,000