Quarterly report pursuant to Section 13 or 15(d)

Income Taxes - Additional Information (Detail)

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Income Taxes - Additional Information (Detail) (USD $)
In Millions, unless otherwise specified
3 Months Ended
Nov. 30, 2013
Nov. 30, 2012
Aug. 31, 2013
Income Tax Disclosure [Abstract]      
Effective income tax rate 7.70% 16.30%  
Discrete income tax benefit $ 7.3 $ 5.5  
Operating Loss Carryforwards   3.4  
Gross liability for unrecognized tax benefits, excluding interest and penalties 18.7   18.0
Liabilities for payment of interest and penalties related to its unrecognized tax benefits $ 3.1   $ 2.9