Share-Based Compensation (Details 2) (USD $) In Millions, except Share data in Thousands, unless otherwise specified	3 Months Ended	9 Months Ended
	May 31, 2013	May 31, 2013
Stock options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized shared-based compensation cost	$ 8.7	$ 8.7
Weighted average period unrecognized share-based compensation expected to be recognized		1 year 6 months
Restricted stock units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized shared-based compensation cost	52.3	52.3
Performance share awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized shared-based compensation cost	$ 2.7	$ 2.7
Restricted stock units and performance share awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards granted	14	133
Weighted average fair value of granted awards	$ 17.70	$ 20.70
Weighted average period unrecognized share-based compensation expected to be recognized		2 years