CONVERTIBLE REDEEMABLE PREFERRED STOCK AND STOCKHOLDERS' EQUITY - Series A Preferred Stock, Convertible Preferred Stock & Warrants (Details) - USD ($)					1 Months Ended						3 Months Ended		12 Months Ended
	Jan. 31, 2017	Nov. 28, 2016	May 15, 2014	May 14, 2014	Apr. 30, 2017	Nov. 30, 2016	Sep. 30, 2016	Aug. 31, 2016	Apr. 30, 2016	Jun. 30, 2015	Apr. 30, 2017	Apr. 30, 2015	Dec. 31, 2014	Mar. 31, 2015
Equity
Conversion of convertible notes payable to common stock (in shares)		1,926,711
Series A convertible preferred stock, shares issued	1,515				1,515	1,515					1,515
Series A convertible preferred stock, shares authorized	10,000,000				10,000,000						10,000,000
Public Offering
Equity
Share price (in dollars per share)									$ 1.195
Number of shares of common stock subject to warrant						31,499,725			1,952,000
Warrants exercise price									$ 1.20
Issuance of common stock (in shares)									3,600,000	3,636,384
Private Placement
Equity
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
Issuance of common stock (in shares)					6,410,258		1,550,000	2,423,077
Warrant
Equity
Warrants exercise price						$ 0.44
Dividend rate							0.00%
Risk-free rate							1.10%
Contractual term							5 years
Expected volatility							95.80%
Warrant liability					$ 767,000		$ 566,000				$ 767,000
Warrant | Minimum
Equity
Warrants, expiration term						5 years
Warrant | Maximum
Equity
Warrants exercise price						$ 0.33
Warrants, expiration term						7 years
Warrant | Public Offering
Equity
Number of shares of common stock subject to warrant						3,246,429			1,952,000
Warrants exercise price						$ 0.35			$ 1.20
Warrant | Public Offering | Underwriters
Equity
Number of shares of common stock subject to warrant										109,091
Warrants exercise price										$ 2.75
Warrants, expiration term										5 years
Warrant | Private Placement
Equity
Number of shares of common stock subject to warrant							1,286,501
Warrants exercise price							$ 0.80
Series A Warrant | Warrant
Equity
Number of shares of common stock subject to warrant													2,042,589
Warrants exercise price													$ 3.70
Series A Convertible Redeemable Preferred Stock | Public Offering
Equity
Number of common shares into which a share is convertible										4,319,426
Series A Convertible Redeemable Preferred Stock | Subscription Agreement
Equity
Number of shares sold													4,207,987
Series A Convertible Redeemable Preferred Stock | Series A Warrant
Equity
Number of shares of common stock subject to warrant	564,662
Warrants exercise price									$ 2.50			$ 2.50		$ 3.70
Proceeds from warrant exercises	$ 1,411,655
Incremental fair value of warrants												$ 436,000
Series A Convertible Redeemable Preferred Stock | Series A Warrant | Public Offering
Equity
Offering price per share that triggers the issuance of additional shares related to the public offering										$ 3.125
Percentage of public offering price										80.00%
Issuance of common stock (in shares)										77,006
Series A Convertible Redeemable Preferred Stock | Series A Warrant | Warrant
Equity
Number of shares of common stock subject to warrant					1,661,055						1,661,055
Dividend rate												0.00%
Risk-free rate												1.60%
Expected volatility												85.90%
Series A Convertible Redeemable Preferred Stock | Series A Warrant | Warrant | Minimum
Equity
Contractual term												4 years
Series A Convertible Redeemable Preferred Stock | Series A Warrant | Warrant | Maximum
Equity
Contractual term												5 years
Series A Convertible Redeemable Preferred Stock | Service Provider Warrant | Warrant
Equity
Number of shares of common stock subject to warrant			316,395
Warrants exercise price			$ 2.035
Warrant expense			$ 99,000
Series A Convertible Redeemable Preferred Stock | Convertible Debt Warrant | Warrant
Equity
Conversion of convertible notes payable to common stock (in shares)										54,054
Number of shares of common stock subject to warrant				343,559	289,505						289,505
Fair value of warrants issued				$ 105,000
Warrants exercise price				$ 1.85
Contractual term			5 years
Series A Convertible Preferred Stock
Equity
Conversion of preferred stock percentage						19.99%
Deemed dividend related to the beneficial conversion feature											$ 100,000
Series A Convertible Preferred Stock | Public Offering
Equity
Share price (in dollars per share)						$ 1,000