Common Stock and Stock Purchase Warrants (Details Textual) - USD ($)			1 Months Ended			12 Months Ended
	Mar. 11, 2015	Dec. 01, 2014	Feb. 28, 2015	Jan. 28, 2013	Mar. 24, 2011	Apr. 30, 2015	Apr. 30, 2014
Stock Issued During Period, Shares, Acquisitions				18,600,000	12,533,333
Common Stock Purchase Price				$ 0.50	$ 0.75
Stock Issued During Period, Value, Share-based Compensation, Gross				$ 9,300,000	$ 9,400,000
Stock Issued During Period, Value, Share-based Compensation, Net of Forfeitures				500,000	$ 500,000
Issuance of Additional Common Shares to Investors						17,617,929
Proceeds from Issuance of Common Stock and Warrants				$ 9,100,000
Estimated Fair Value of Warrants	$ 1,600,000						$ 2,000,000
Repurchase Of Stock In Put Option						$ 0.40
Common Stock, Shares Authorized						200,000,000	125,000,000
Warrant Modification Charge						$ 586,000	$ 0
Securities Purchase Agreement 2011 [Member]
Warrants Exercise Price Per Share					$ 0.40
Stock Issued During Period, Shares, New Issues					2,264,450
Additional Warrants Issued To Investors					1,583,335
Warrant Modification Charge					$ 413,521
Securities Purchase Agreement 2013 [Member]
Warrants Exercise Price Per Share				$ 0.40
Additional Warrants Issued To Investors				1,209,001
Warrant Modification Charge				$ 172,344
Securities Purchase Agreement 2015 [Member]
Debt Conversion, Original Debt, Amount	$ 100,000
Unit Description	each unit consisting of one share of the Company's Common Stock, par value $0.001 per share (the "Common Stock") and a warrant to buy 0.55 shares of Common Stock at $0.48 per share (the "Warrants"), at a purchase price of $0.40 per unit, for an aggregate of $14,000,000.
Debt Instrument, Increase, Accrued Interest	$ 60,000
Debt Conversion Converted Instrument Discount Rate	5.00%
Convertible Promissory Notes [Member]
Debt Conversion, Original Debt, Amount		$ 1,000,000
Short-term Debt, Percentage Bearing Fixed Interest Rate		12.00%
Short-term Debt, Terms		90 days
Debt Instrument, Maturity Date			Apr. 01, 2015
Term Of Warrants		5 years
Convertible Debt [Member]
Debt Instrument, Increase, Accrued Interest	$ 60,000
Debt Conversion Converted Instrument Discount Rate	5.00%
January 2013 Private Placement [Member]
Common Stock Purchase Price						$ 0.50
Warrants Issued During Period for Common Stock						1,860,000
Warrants Exercise Price Per Share						$ 0.66
Percentage of Common Stock Purchased						25.00%
Issuance of Additional Common Shares to Investors						1,064,658
Net Shares Reclassified to Mandatorily Redeemable Capital Stock, Value						$ 8,800,000
Proceeds from Issuance of Common Stock and Warrants						9,300,000
Proceeds from Issuance of Warrants						400,000
Incremental Compensation Cost						$ 200,000
April 2011 Private Placement [Member]
Common Stock Purchase Price						$ 0.75
Warrants Issued During Period for Common Stock						1,266,667
Warrants Exercise Price Per Share						$ 0.90
Percentage of Common Stock Purchased						25.00%
Net Shares Reclassified to Mandatorily Redeemable Capital Stock, Value						$ 8,200,000
Proceeds from Issuance of Common Stock and Warrants						9,400,000
Proceeds from Issuance of Warrants						900,000
Incremental Compensation Cost						$ 300,000
April 2011 Private Placement [Member] | Minimum [Member]
Warrants Exercise Price Per Share						$ 0.50
April 2011 Private Placement [Member] | Maximum [Member]
Warrants Exercise Price Per Share						$ 0.90
March 2015 Private Placement [Member]
Net Shares Reclassified to Mandatorily Redeemable Capital Stock, Value						$ 8,000,000
Proceeds from Issuance of Common Stock and Warrants						14,000,000
Proceeds from Issuance of Warrants						5,100,000
Incremental Compensation Cost						880,000
Warrants and Rights Outstanding						$ 1,600,000