ORGANIZATION AND BUSINESS (Details) - USD ($)			3 Months Ended		6 Months Ended
	Sep. 18, 2017	Nov. 09, 2016	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017	Sep. 20, 2016	Sep. 24, 2015
Debt Instrument [Line Items]
Accumulated deficit			$ 310,329,000		$ 310,329,000		$ 299,848,000
Cash and cash equivalents			7,008,000		7,008,000		22,632,000
Working capital			35,800,000		35,800,000
Revenue			20,713,000	$ 17,256,000	37,437,000	$ 32,555,000
Loans Payable
Debt Instrument [Line Items]
Original principal amount			35,500,000		$ 35,500,000		$ 35,500,000	$ 35,500,000	$ 27,500,000
Common Stock
Debt Instrument [Line Items]
Common stock issuances (in shares)					0	382,308
Common stock issuances					$ 0	$ 1,300,000
Common Stock | Common Stock Purchase Agreement with Aspire Capital Fund, LLC
Debt Instrument [Line Items]
Stock purchase obligation		$ 20,000,000.0
Period of purchase stock		30 months
Common Stock | First Amendment to Common Stock Purchase Agreement with Aspire Capital Fund, LLC
Debt Instrument [Line Items]
Increase in number of shares to be purchased (in shares)	2,000,000
Value of shares purchased to date			$ 12,800,000		$ 12,800,000