Quarterly report pursuant to Section 13 or 15(d)

Income Taxes (Details)

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Income Taxes (Details) (USD $)
In Millions, unless otherwise specified
3 Months Ended
Nov. 30, 2011
Nov. 30, 2010
Aug. 31, 2011
Income Taxes [Abstract]      
Effective income tax rate 23.10% 20.60%  
Gross liability for unrecognized tax benefits, excluding interest and penalties $ 27.2   $ 26.2
Liabilities for the payment of interest and penalties related to its unrecognized tax benefits $ 5.3   $ 5.1