Share-Based Payments - Stock Option Activity (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Aug. 31, 2013
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Outstanding, Beginning balance, Number of Shares	2,262,679
Granted, Number of Shares	364,160
Exercised, Number of Shares	(773,942)
Cancelled, Number of Shares	(56,909)
Outstanding, Ending balance, Number of Shares	1,795,988
Exercisable, Number of Shares	899,079
Expected to vest, Number of Shares	896,909
Available for future grants, Number of Shares	2,085,615
Outstanding, Beginning balance, Weighted Average Exercise Price	$ 173.01
Granted, Weighted Average Exercise Price	$ 371.76
Exercised, Weighted Average Exercise Price	$ 128.68
Cancelled, Weighted Average Exercise Price	$ 282.28
Outstanding, Ending balance, Weighted Average Exercise Price	$ 228.95
Exercisable, Weighted Average Exercise Price	$ 152.35
Expected to vest, Weighted Average Exercise Price	$ 305.74
Outstanding , Weighted-Average Remaining Contractual Term	6 years 6 months 22 days
Exercisable, Weighted-Average Remaining Contractual Term	5 years 18 days
Expected to vest, Weighted-Average Remaining Contractual Term	8 years 26 days
Outstanding, Aggregate Intrinsic Value	$ 343,015
Exercisable, Aggregate Intrinsic Value	240,584
Expected to vest, Aggregate Intrinsic Value	$ 92,187