Investments (Realized Net Gains (Losses) Related To Available-For-Sale Investments) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Apr. 25, 2015	Apr. 26, 2014	Apr. 25, 2015	Apr. 26, 2014
Schedule of Available-for-sale Securities [Line Items]
Total	$ 44	$ 69	$ 120	$ 234
Net gains on investments in publicly traded equity securities
Schedule of Available-for-sale Securities [Line Items]
Total	38	55	94	199
Net gains on investments in fixed income securities
Schedule of Available-for-sale Securities [Line Items]
Total	$ 6	$ 14	$ 26	$ 35