Annual report pursuant to Section 13 and 15(d)

Weighted-Average Assumptions (Detail)

v2.4.0.6
Weighted-Average Assumptions (Detail)
12 Months Ended
Aug. 31, 2012
Aug. 31, 2011
Aug. 31, 2010
Schedule of Weighted Average Assumptions for Fair Values of Stock Options[Line Items]      
Dividend yield 0.18% 0.15% 0.23%
Expected volatility 39.97% 39.62% 40.01%
Risk-free rate of return 1.19% 2.53% 2.76%
Expected forfeiture rate 15.00% 15.00% 15.00%
Expected life 6 years 1 month 6 days 6 years 1 month 6 days 6 years 1 month 6 days