Employee Benefit Plans (Summary of Share-Based Awards available for Grant) (Details) - shares shares in Millions	6 Months Ended	12 Months Ended
	Jan. 28, 2017	Jul. 30, 2016
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding [Roll Forward]
Balance, beginning of period (in shares)	242	276
Restricted stock, stock units, and other share-based awards granted (in shares)	(43)	(96)
Share-based awards canceled/forfeited/expired (in shares)	69	30
Shares withheld for taxes and not issued (in shares)	20	30
Other (in shares)		2
Balance, end of period (in shares)	288	242