Weighted Average Assumptions used in Black-Scholes Option Pricing Model (Detail) (Employee Stock Purchase Plan)	12 Months Ended
	Aug. 31, 2012	Aug. 31, 2011	Aug. 31, 2010
Employee Stock Purchase Plan
Schedule of Weighted Average Assumptions for Fair Values of Stock Options[Line Items]
Expected dividend yield	0.70%	0.90%	1.50%
Risk-free interest rate	0.10%	0.20%	0.30%
Expected volatility	48.40%	47.30%	79.70%
Expected life	6 months	6 months	6 months