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Share-Based Compensation (Schedule Of Weighted-Average Assumptions Used To Estimate Fair Value Of Option Grant) (Details)	0 Months Ended		9 Months Ended
	Apr. 24, 2013	Apr. 17, 2013	Apr. 30, 2013	Apr. 30, 2012
Share-based Compensation [Abstract]
Volatility	140.75%	140.63%	134.80%	81.59%
Risk-free interest rate	0.43%	0.44%	0.85%	1.17%
Dividend yield	0.00%	0.00%	0.00%	0.00%
Expected life			5 years 22 days	4 years 9 months 26 days

The estimated measure of the percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period.

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