Goodwill and Other Intangible Assets - Additional Information (Detail) (USD $)	3 Months Ended
	Nov. 30, 2012	Nov. 30, 2011
Finite-Lived Intangible Assets [Line Items]
Amortization expense of intangible assets	$ 7,854,000	$ 7,218,000
Future amortization expense, 2013	22,000,000
Future amortization expense, 2014	28,100,000
Future amortization expense, 2015	28,000,000
Future amortization expense, 2016	27,900,000
Future amortization expense, 2017	26,700,000
Future amortization expense, 2018	26,300,000
Future amortization expense, thereafter	$ 143,200,000