Stock-Based Compensation (Stock-Based Compensation Expense) (Details) (USD $)	12 Months Ended
	Aug. 31, 2011		Aug. 31, 2010	Aug. 31, 2009
Stock-based compensation	$ 25,773,000	[1]	$ 14,065,000	$ 13,623,000
Tax impact of stock-based compensation	(7,990,000)		(4,627,000)	(4,550,000)
Stock-based compensation, net of tax	17,783,000		9,438,000	9,073,000
Unrecognized stock-based compensation expense	44,300,000
Weighted-average period of recognition (years)	3.2
Stock-based compensation capitalized amount	0
Performance-Based Options [Member]
Stock-based compensation	7,900,000
Stock-based compensation, net of tax	$ 5,400,000

[1] Included in fiscal 2011 was a pre-tax stock-based compensation charge of $7.9 million ($5.4 million after-tax) from an increase in the estimated number of performance-based options that will vest due to accelerating levels of ASV and diluted EPS than previously expected. The revised estimate reflects a higher performance level than previously estimated and accordingly, increased the number of performance-based options that will vest and be expensed.