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 9 Months Ended
May 31, 2014
May 31, 2013
May 31, 2014
May 31, 2013
Aug. 31, 2013
Income Tax Disclosure [Abstract]          
Discrete item $ 10.5        
Effective income tax rate 3.20% 7.70% 11.30% 12.50%  
Reversal of tax reserves 6.8 9.3      
Gross liability for unrecognized tax benefits, excluding interest and penalties 31.6   31.6   18.0
Liabilities for payment of interest and penalties related to its unrecognized tax benefits $ 1.7   $ 1.7   $ 2.9