Share Repurchases (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended
	May 03, 2015	Apr. 27, 2014
Statement [Line Items]
Shares repurchased, value	$ (192)	$ (76)
June 2011 Program [Member]
Statement [Line Items]
Authorized amount for shares repurchase	1,000
Stock Repurchase Program, Remaining Authorized Repurchase Amount	600
Treasury Stock [Member]
Statement [Line Items]
Treasury stock purchased, shares	4	2
Shares repurchased, value	(192)	(76)
Treasury Stock [Member] | June 2011 Program [Member]
Statement [Line Items]
Shares repurchased, value	(150)
Treasury Stock [Member] | Shares Repurchased To Offset The Impact Of Dilution [Member]
Statement [Line Items]
Treasury stock purchased, shares		2
Shares repurchased, value		$ (76)