Intangibles and Other Assets, net - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Aug. 31, 2012	Aug. 31, 2011	Aug. 31, 2010
Schedule of Intangible Assets Disclosure [Line Items]
Amortization expense	$ 5.6	$ 4.7	$ 4.8
Future amortization expense, 2013	4.2
Future amortization expense, 2014	4.1
Future amortization expense, 2015	4.1
Future amortization expense, 2016	4.1
Future amortization expense, 2017	$ 3.9