Employee Benefit Plans (Summary Assumptions Related To And Valuation Of Employee Share-Based Awards (Time-Based Restricted Stock Units)) (Detail) (Time Based Restricted Stock Units R S U [Member], USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended
	Oct. 27, 2012	Oct. 29, 2011
Time Based Restricted Stock Units R S U [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share Based Compensation Arrangement By Share Based Payment Award Equivalent Number Of Shares For Full Value Awards	11	11
Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Stock Price	$ 17.65	$ 15.69
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate	2.90%	1.50%