Redeemable Common Stock and Stock Purchase Warrants (Details) (Warrant [Member])	6 Months Ended	12 Months Ended
Oct. 31, 2013	Apr. 30, 2013
Minimum [Member]
Expected term in years	2 years 4 months 24 days	2 years 10 months 24 days
Risk-free interest rates	0.50%
Volatility	91.00%	95.00%
Dividend yield		0.00%
Maximum [Member]
Expected term in years	4 years 2 months 12 days	4 years 8 months 12 days
Risk-free interest rates	1.10%	0.30%
Volatility	107.00%	98.00%
Dividend yield		0.00%

Expected dividends to be paid to holders of the underlying shares or financial instruments (expressed as a percentage of the share or instrument's price).

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (e)

-URI http://asc.fasb.org/extlink&oid=25499696&loc=d3e19207-110258

+ Details

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- Definition

Period the instrument, asset or liability is expected to be outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

+ Details

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- Definition

Measure of dispersion, in percentage terms (for instance, the standard deviation or variance), for a given stock price.

+ References

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- Definition

Risk-free interest rate assumption used in valuing an instrument.

+ References

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