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Schedule of ESPP Weighted-Average Assumptions (Detail)	3 Months Ended	9 Months Ended
Schedule of ESPP Weighted-Average Assumptions (Detail)	Mar. 31, 2013	Mar. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term (years)	6 months 4 days	7 months 24 days
Expected stock price volatility	29.81%	32.54%
Risk-free interest rate	0.12%	0.15%

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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