Employee Benefit Plans (Summary of Share-Based Awards available for Grant) (Details) - shares	6 Months Ended	12 Months Ended
	Jan. 27, 2018	Jul. 29, 2017
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding [Roll Forward]
Balance, beginning of period (in shares)	272,000,000	242,000,000
Restricted stock, stock units, and other share-based awards granted (in shares)	(46,000,000)	(76,000,000)
Share-based awards canceled/forfeited/expired (in shares)	10,000,000	78,000,000
Shares withheld for taxes and not issued (in shares)	18,000,000	28,000,000
Balance, end of period (in shares)	254,000,000	272,000,000