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Summary of Significant Accounting Policies - Additional Information (Detail) (USD $)
In Millions, unless otherwise specified
9 Months Ended
Apr. 28, 2012
Apr. 30, 2011
Jul. 30, 2011
Significant Accounting Policies [Line Items]      
Unrecognized tax benefits (including accrued interest and penalties) $ 11.3   $ 21.9
Estimated decrease in unrecognized tax benefits, over the next twelve months (4.8)    
Decrease in liability for uncertain tax position primarily as a result of the settlement of federal income tax audits $ 10.6    
Anti-dilutive options and/or contingent vesting of performance-based and market-based restricted stock units that were excluded from diluted share calculations 3.2 3.6