Annual report pursuant to Section 13 and 15(d)

Goodwill and Other Intangible Assets - Additional Information (Detail)

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Goodwill and Other Intangible Assets - Additional Information (Detail) (USD $)
 12 Months Ended
Aug. 31, 2012
Aug. 31, 2011
Aug. 31, 2010
Goodwill [Line Items]      
Cumulative goodwill impairment charges $ 58,800,000 $ 22,200,000  
Amortization expense of intangible assets 29,274,000 27,467,000 22,017,000
Future amortization expense, 2013 29,700,000    
Future amortization expense, 2014 28,100,000    
Future amortization expense, 2015 28,000,000    
Future amortization expense, 2016 27,800,000    
Future amortization expense, 2017 26,600,000    
Future amortization expense, thereafter $ 168,300,000