Derivative Instruments (Effect Of Derivative Instruments Designated As Cash Flow Hedges And Net Investment Hedging Instruments On Other Comprehensive And Consolidated Statements Of Operations Summary) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Oct. 26, 2013	Oct. 27, 2012
Cash Flow Hedging [Member]
Derivative [Line Items]
Gains (losses) recognized in OCI on derivatives (effective portion)	$ 38	$ 66
Gains (losses) reclassified from AOCI into income (effective portion)	9	(5)
Cash Flow Hedging [Member] | Foreign Currency Derivatives-Cash Flow Hedges [Member]
Derivative [Line Items]
Gains (losses) recognized in OCI on derivatives (effective portion)	38	66
Cash Flow Hedging [Member] | Foreign Currency Derivatives-Cash Flow Hedges [Member] | Operating Expenses [Member]
Derivative [Line Items]
Gains (losses) reclassified from AOCI into income (effective portion)	7	(4)
Cash Flow Hedging [Member] | Foreign Currency Derivatives-Cash Flow Hedges [Member] | Cost Of Sales-Service [Member]
Derivative [Line Items]
Gains (losses) reclassified from AOCI into income (effective portion)	2	(1)
Net Investment Hedging [Member]
Derivative [Line Items]
Gains (losses) recognized in OCI on derivatives (effective portion)	(19)	(24)
Net Investment Hedging [Member] | Other income (loss), net [Member]
Derivative [Line Items]
Gains (losses) reclassified from AOCI into income (effective portion)	$ 0	$ 0