Stock-Based Awards - Valuation of Stock Options and Restricted Share Units (Details) (USD $)	3 Months Ended
	Oct. 26, 2013
Stock Options
Stock Options, Outstanding [Roll Forward]
Outstanding beginning period	2,769,132
Options Exercised	(454,216)
Outstanding ending period	2,314,916
Exercisable options beginning period	1,424,099
Stock Options, Outstanding, Weighted Average Exercise Price [Roll Forward]
Outstanding beginning period	$ 18.27
Options Exercised	$ 22.29
Outstanding ending period	$ 17.48
Exercisable options beginning period	$ 19.70
Restricted Share Units (RSUs)
Share Based Compensation Arrangement By Share Based Payment Award Non Option Equity Instruments Outstanding [Roll Forward]
Outstanding beginning period	463,318
Share Units Vested	(1,035)
Forfeited or cancelled	0
Outstanding ending period	463,318.000
Performance Restricted Share Units
Share Based Compensation Arrangement By Share Based Payment Award Non Option Equity Instruments Outstanding [Roll Forward]
Outstanding beginning period	1,315,138
Share Units Vested	(43,979)
Forfeited or cancelled	(265,461)
Outstanding ending period	1,070,852.000