Share Repurchases (Details) - USD ($) shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jan. 27, 2019	Jan. 28, 2018	Jan. 27, 2019	Jan. 28, 2018
Statement [Line Items]
Shares repurchased, value	$ 0	$ 0	$ 0	$ 86
March 2017 Program [Member]
Statement [Line Items]
Authorized amount for shares repurchase	1,500		1,500
Stock Repurchase Program, Remaining Authorized Repurchase Amount	$ 1,296		$ 1,296
Treasury Stock [Member]
Statement [Line Items]
Treasury stock purchased, shares	0	0	0	2
Shares repurchased, value	$ 0	$ 0	$ 0	$ 86