Intangibles and Other Assets, Net - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	May 31, 2013	May 31, 2012	May 31, 2013	May 31, 2012
Schedule of Intangible Assets Disclosure [Line Items]
Amortization expense	$ 1.0	$ 1.1	$ 3.3	$ 3.4
Future amortization expense, 2013	4.2		4.2
Future amortization expense, 2014	4.0		4.0
Future amortization expense, 2015	4.0		4.0
Future amortization expense, 2016	4.0		4.0
Future amortization expense, 2017	$ 3.8		$ 3.8