Stock Compensation Information (Summary Of Fair Value Assumptions) (Details) (USD $)	6 Months Ended
Oct. 31, 2012	Oct. 31, 2011
Stock Compensation Information [Abstract]
Expected term (in years)	4 years	4 years
Risk-free interest rate	0.50%	0.80%
Volatility	80.00%	89.00%
Dividend yield
Weighted-average fair value of stock options granted during the year	$ 1.02	$ 2.39

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The estimated dividend rate (a percentage of the share price) to be paid (expected dividends) to holders of the underlying shares over the option's term.

+ References

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- Definition

Expected term of share-based compensation awards, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

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

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-Name Staff Accounting Bulletin (SAB)

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-Section D

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- Definition

The risk-free interest rate assumption that is used in valuing an option on its own shares.

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- Definition

The range of expected volatilities used and the weighted-average expected volatility for an entity using a valuation technique with different volatilities during the contractual term.

+ References

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- Definition

The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology.

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