Derivative Instruments (Effect Of Derivative Instruments Not Designated As Fair Value Hedges On Consolidated Statement Of Operations Summary) (Details) (Derivatives Not Designated As Hedging Instruments [Member], USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jan. 26, 2013	Jan. 28, 2012	Jan. 26, 2013	Jan. 28, 2012
Derivative [Line Items]
Gains (losses) recognized in income	$ (19)	$ (93)	$ 57	$ (163)
Foreign Exchange Contract [Member] | Other Income [Member]
Derivative [Line Items]
Gains (losses) recognized in income	(41)	(88)	12	(145)
Total Return Swaps-Deferred Compensation [Member] | Cost of Sales [Member]
Derivative [Line Items]
Gains (losses) recognized in income	0	3	0	3
Total Return Swaps-Deferred Compensation [Member] | Operating Expenses [Member]
Derivative [Line Items]
Gains (losses) recognized in income	19	10	33	(10)
Equity Derivatives [Member] | Other Income [Member]
Derivative [Line Items]
Gains (losses) recognized in income	$ 3	$ (18)	$ 12	$ (11)