Common Stock - Narrative (Details) - USD ($)					1 Months Ended	12 Months Ended
	Mar. 11, 2015	Dec. 01, 2014	Jan. 28, 2013	Mar. 24, 2011	Feb. 28, 2015	Apr. 30, 2016	Apr. 30, 2015	Apr. 24, 2015	Apr. 23, 2015
Class of Stock [Line Items]
Common stock, par value (in dollars per share)	$ 0.001					$ 0.001	$ 0.001
Percentage of share to be purchased by warrant	0.55%
Exercise price of warrant (in usd per share)	$ 5.76
Repurchase of stock in put option (in usd per share)	$ 4.80
Term of warrant						5 years
Modification of warrant liability						$ 0	$ 586,000
Common stock, shares authorized (in shares)						200,000,000	125,000,000	200,000,000	125,000,000
Securities Purchase Agreement 2011 [Member]
Class of Stock [Line Items]
Issuance of share under anti-dilution provisions (in shares)				188,704
Additional warrants issued to investors (in shares)				131,945
Warrants exercise price per share (in dollars per share)				$ 4.8
Modification of warrant liability				$ 413,521
Securities Purchase Agreement 2013 [Member]
Class of Stock [Line Items]
Additional warrants issued to investors (in shares)			100,750
Warrants exercise price per share (in dollars per share)			$ 4.8
Modification of warrant liability			$ 172,344
Securities Purchase Agreement 2015 [Member]
Class of Stock [Line Items]
Debt conversion, original amount	$ 100,000
Debt instrument, increase, accrued interest	$ 60,000
Debt conversion, converted instrument, discount rate	5.00%
Convertible Promissory Notes [Member]
Class of Stock [Line Items]
Debt conversion, original amount		$ 1,000,000
Short-term debt, percentage bearing fixed interest rate		12.00%
Short-term debt, terms		90 days
Term of short-term debt		90 days
Debt instrument, maturity date					Apr. 01, 2015
Convertible Debt [Member]
Class of Stock [Line Items]
Debt instrument, increase, accrued interest	$ 60,000
Debt conversion, converted instrument, discount rate	5.00%
March 2015 Private Placement [Member]
Class of Stock [Line Items]
Proceeds from issuance of common stock and warrants	$ 14,000,000
Net shares reclassified to mandatory redeemable capital stock, value	8,000,000
Proceeds from issuance of warrants	5,100,000
Incremental compensation cost	$ 880,000
Warrants and rights outstanding						$ 1,600,000