Investments (Realized Net Gains (Losses) Related To Available-For-Sale Investments) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jan. 24, 2015	Jan. 25, 2014	Jan. 24, 2015	Jan. 25, 2014
Schedule of Available-for-sale Securities [Line Items]
Total	$ 69	$ 82	$ 76	$ 165
Net gains (losses) on investments in publicly traded equity securities
Schedule of Available-for-sale Securities [Line Items]
Total	60	69	56	144
Net gains on investments in fixed income securities
Schedule of Available-for-sale Securities [Line Items]
Total	$ 9	$ 13	$ 20	$ 21