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Stock Compensation - Estimated Fair Value of Each Option Grant (Detail) (USD $)	3 Months Ended
	Sep. 30, 2012	Sep. 30, 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility (based on historical data)	33.30%	29.00%
Expected life in years	4 years	4 years 9 months
Risk-free interest rate	0.71%	1.15%
Fair value per award	$ 2.34	$ 1.82

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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