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
	Oct. 27, 2012	Oct. 29, 2011
Derivative [Line Items]
Gains (losses) recognized in income	$ 76	$ (70)
Foreign Exchange Contract [Member] | Other Income [Member]
Derivative [Line Items]
Gains (losses) recognized in income	53	(57)
Total Return Swaps-Deferred Compensation [Member] | Operating Expenses [Member]
Derivative [Line Items]
Gains (losses) recognized in income	14	(20)
Equity Derivatives [Member] | Other Income [Member]
Derivative [Line Items]
Gains (losses) recognized in income	$ 9	$ 7