Investments (Realized Net Gains (Losses) Related To Available-For-Sale Investments) (Details) - USD ($) $ in Millions	12 Months Ended
	Jul. 29, 2017	Jul. 30, 2016	Jul. 25, 2015
Schedule of Available-for-sale Securities [Line Items]
Total	$ (87)	$ (1)	$ 157
Net gains/(losses) on investments in publicly traded equity securities
Schedule of Available-for-sale Securities [Line Items]
Total	(45)	33	116
Net gains/(losses) on investments in fixed income securities
Schedule of Available-for-sale Securities [Line Items]
Total	$ (42)	$ (34)	$ 41