Stock-based Compensation - Additional Information (Detail) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended		1 Months Ended		3 Months Ended
	Oct. 29, 2011 Year	Oct. 30, 2010	Sep. 23, 2010 The 2010 Stock Plan	Oct. 29, 2011 The 2010 Stock Plan	Oct. 29, 2011 Restricted Equity Awards	Oct. 29, 2011 Service-based Restricted Equity Awards Year	Oct. 29, 2011 Performance-based Restricted Equity Awards Year	Oct. 29, 2011 Market-based Restricted Equity Awards Year
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Aggregate number of share that may be issued under Stock Incentive Plan			18,000,000
Shares available for future grants under stock incentive plan				3,900,000
Total unrecognized compensation cost	$ 33.4					$ 11.0	$ 15.8	$ 3.3
Weighted-average recognition period for unrecognized compensation cost (years)	3.0					3.5	2.1	2.0
Total intrinsic value of options exercised	1.7	1.1
Total fair value of options vested	$ 7.2	$ 14.7
Share based award description					The 2010 Stock Plan also allows for the issuance of shares of restricted stock and restricted stock units ("RSUs"). Any shares of restricted stock or RSUs are counted against the shares available for future grant limit as three shares for every one restricted share or unit granted. In general, if options are cancelled for any reason or expire, the shares covered by such options again become available for grant. If a share of restricted stock or an RSU unit is forfeited for any reason, three shares become available for grant.
Number of shares issuable per vesting of one restricted stock or unit					3
Number of shares available for grant upon forfeiture of a restricted stock or unit					3
Vesting period						4 years	3 years	3 years