Weighted Average Assumptions used in Black-Scholes Option Pricing Model (Detail) (Employee Stock Purchase Plan)	12 Months Ended
	Aug. 31, 2014	Aug. 31, 2013	Aug. 31, 2012
Employee Stock Purchase Plan
Schedule of Weighted Average Assumptions for Fair Values of Stock Options[Line Items]
Expected dividend yield	0.90%	0.80%	0.70%
Risk-free interest rate	0.10%	0.10%	0.10%
Expected volatility	33.80%	34.70%	48.40%
Expected life	6 months	6 months	6 months