CONVERTIBLE REDEEMABLE PREFERRED STOCK AND STOCKHOLDERS' EQUITY - Common Stock (Details) - USD ($)				1 Months Ended								3 Months Ended		12 Months Ended
	Nov. 28, 2016	Aug. 17, 2016	Oct. 24, 2014	Apr. 30, 2017	Dec. 31, 2016	Nov. 30, 2016	Sep. 30, 2016	Aug. 31, 2016	Apr. 30, 2016	Dec. 31, 2015	Jun. 30, 2015	Apr. 30, 2017	Apr. 30, 2016	Jan. 31, 2017
Conversion of convertible notes payable to common stock (in shares)	1,926,711
Shares issued				74,129,835								74,129,835		67,719,577
Net proceeds from issuance of common stock, preferred stock and warrants												$ 4,444,000	$ 3,583,000
Conversion price (in dollars per share)		$ 0.80
Beneficial conversion feature														$ 88,000
Debt issuance costs		$ 16,000
Secured Convertible Notes Payable
Conversion of convertible notes payable to common stock (in shares)											182,266
Convertible notes payable, net		$ 1,000,000
Maturity term (in months)		36 months
Interest rate (as a percentage)		10.00%
Warrant
Warrants exercise price						$ 0.44
Warrant | Maximum
Warrants exercise price						$ 0.33
Warrants, expiration term						7 years
Warrant | Minimum
Warrants, expiration term						5 years
Unsecured Convertible Notes Payable
Convertible notes payable, net		$ 500,000
Maturity term (in months)		6 months
Interest rate (as a percentage)		10.00%
Public Offering
Issuance of stock (in shares)									3,600,000		3,636,384
Net proceeds from the sale of common stock											$ 7,800,000
Share price (in dollars per share)									$ 1.195				$ 1.195
Net proceeds from issuance of common stock and warrants									$ 3,600,000
Net proceeds from issuance of common stock, preferred stock and warrants						$ 10,600,000
Number of shares of common stock subject to warrant						31,499,725			1,952,000				1,952,000
Warrants exercise price									$ 1.20				$ 1.20
Public Offering | Common Stock
Issuance of stock (in shares)						31,489,429
Share price (in dollars per share)						$ 0.35
Public Offering | Preferred Stock
Issuance of stock (in shares)						1,515
Public Offering | Warrant
Number of shares of common stock subject to warrant						3,246,429			1,952,000				1,952,000
Warrants exercise price						$ 0.35			$ 1.20				$ 1.20
Public Offering | Series A Convertible Preferred Stock
Share price (in dollars per share)						$ 1,000
Private Placement
Issuance of stock (in shares)				6,410,258			1,550,000	2,423,077
Net proceeds from the sale of common stock				$ 4,400,000			$ 800,000	$ 1,300,000
Shares issued				0.78								0.78
Share price (in dollars per share)							$ 0.60	$ 0.65
Number of shares of common stock subject to warrant				3,365,385			1,286,501					3,365,385
Warrants exercise price				$ 0.90			$ 0.80					$ 0.90
Warrants, expiration term				5 years			5 years
Private Placement | Warrant
Number of shares of common stock subject to warrant							1,286,501
Warrants exercise price							$ 0.80
Over-Allotment Option
Net proceeds from the sale of common stock					$ 400,000
Shares issued					1,390,676
Korea Investment Partners
Shares issued			290,000
Stock vested			96,667
Stock not expected to vest			193,333
Korea Investment Partners | Subscription Agreement | Common Stock
Shares issued			1,081,081
Share price (in dollars per share)			$ 1.85
Revenue from Violet			$ 2,000,000
Subscription agreement receivable			$ 2,000,000
Korea Investment Partners | Subscription Agreement | Common Stock | Minimum
Share price (in dollars per share)			$ 3.70
Franklin Advisers | Private Placement
Issuance of stock (in shares)										4,100,000
Net proceeds from the sale of common stock										$ 5,500,000
Share price (in dollars per share)										$ 1.43
Period within which securities can be purchased										5 years
Franklin Advisers | Private Placement | Maximum
Percentage of securities offered by entity										20.00%