Derivative Instruments (Effect Of Derivative Instruments Designated As Cash Flow Hedges On Other Comprehensive And Consolidated Statements Of Operations Summary) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Oct. 27, 2012	Oct. 29, 2011
Cash Flow Hedging [Member]
Derivative [Line Items]
Gains (losses) recognized in OCI on derivatives (effective portion)	$ 66	$ (50)
Gains (losses) reclassified from AOCI into income (effective portion)	(5)	0
Cash Flow Hedging [Member] | Foreign Currency Derivatives-Cash Flow Hedges [Member]
Derivative [Line Items]
Gains (losses) recognized in OCI on derivatives (effective portion)	66	(50)
Cash Flow Hedging [Member] | Operating Expenses [Member] | Foreign Currency Derivatives-Cash Flow Hedges [Member]
Derivative [Line Items]
Gains (losses) reclassified from AOCI into income (effective portion)	(4)	0
Cash Flow Hedging [Member] | Cost Of Sales-Service [Member] | Foreign Currency Derivatives-Cash Flow Hedges [Member]
Derivative [Line Items]
Gains (losses) reclassified from AOCI into income (effective portion)	(1)	0
Net Investment Hedging [Member]
Derivative [Line Items]
Gains (losses) recognized in OCI on derivatives (effective portion)	(24)	(4)
Net Investment Hedging [Member] | Other income (loss), net [Member]
Derivative [Line Items]
Gains (losses) reclassified from AOCI into income (effective portion)	$ 0	$ 0