Share Repurchases (Details) - USD ($) shares in Millions, $ in Millions	9 Months Ended
	Apr. 30, 2017	May 01, 2016
Statement [Line Items]
Shares repurchased, value	$ 305	$ 118
June 2011 Program [Member]
Statement [Line Items]
Authorized amount for shares repurchase	1,000
March 2017 Program [Domain]
Statement [Line Items]
Authorized amount for shares repurchase	$ 1,500
Treasury Stock [Member]
Statement [Line Items]
Treasury stock purchased, shares	5	2
Shares repurchased, value	$ 305	$ 118
Treasury Stock [Member] | June 2011 Program [Member]
Statement [Line Items]
Shares repurchased, value	$ 271