Share Repurchases (Details) (USD $) In Millions, except Share data in Thousands, unless otherwise specified	3 Months Ended		28 Months Ended	3 Months Ended
	Oct. 27, 2013	Oct. 28, 2012	Oct. 27, 2013 June 2011 Program [Member]	Oct. 27, 2013 Treasury Stock [Member]	Oct. 28, 2012 Treasury Stock [Member]	Oct. 27, 2013 Treasury Stock [Member] Shares Repurchased To Offset The Impact Of Dilution [Member]	Oct. 28, 2012 Treasury Stock [Member] Shares Repurchased To Offset The Impact Of Dilution [Member]
Statement [Line Items]
Authorized amount for shares repurchase			$ 1,000
Stock Repurchase Program, Remaining Authorized Repurchase Amount			750
Shares repurchased, shares				0	0	43	480
Shares repurchased, value	$ 2	$ 17		$ 2	$ 17