Share-Based Compensation (Details 2) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended	9 Months Ended
	May 31, 2012	May 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Increase in shares reserved for issuance		3,500,000
Stock options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized shared-based compensation cost	$ 17.9	$ 17.9
Weighted average period unrecognized share-based compensation expected to be recognized		1.45
Restricted stock units and performance share awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized shared-based compensation cost	$ 80.0	$ 80.0
Awards other than options granted	161,000	247,000
Weighted average grant date fair value other than options	$ 38.71	$ 40.86
Weighted average period unrecognized share-based compensation expected to be recognized		1.87