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Summary of Weighted-Average Assumptions (Detail)	3 Months Ended	9 Months Ended
Summary of Weighted-Average Assumptions (Detail)	Mar. 31, 2013	Mar. 31, 2013	Mar. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Dividend rate
Price volatility	92.00%	89.00%	62.00%
Risk-free interest rate	0.80%	0.86%
Expected life	5 years 2 months 12 days	5 years 8 months 12 days	6 years
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate			1.00%
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate			1.30%

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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