Goodwill and Intangible Assets (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	May 31, 2012	May 31, 2011	May 31, 2012	May 31, 2011
Goodwill and Intangible Assets Disclosure [Abstract]
Increases in gross carrying amounts for acquired intangible assets, including goodwill			$ 2.6
Amortization expense of finite-lived intangible assets	2.7	3.0	8.5	7.7
Finite-Lived Intangible Assets, Future Amortization Expense [Abstract]
Amortization expense in fiscal 2012			11.1
Amortization expense in fiscal 2013			10.0
Amortization expense in fiscal 2014			10.0
Amortization expense in fiscal 2015			9.7
Amortization expense in fiscal 2016			$ 9.1