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		6 Months Ended
	Jan. 26, 2013	Jan. 28, 2012	Jan. 26, 2013	Jan. 28, 2012
Cash Flow Hedging [Member]
Derivative [Line Items]
Gains (losses) recognized in OCI on derivatives (effective portion)	$ 3	$ (44)	$ 69	$ (94)
Gains (losses) reclassified from AOCI into income (effective portion)	8	(26)	3	(26)
Cash Flow Hedging [Member] | Foreign Currency Derivatives-Cash Flow Hedges [Member]
Derivative [Line Items]
Gains (losses) recognized in OCI on derivatives (effective portion)	3	(44)	69	(94)
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)	6	(22)	2	(22)
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)	2	(4)	1	(4)
Net Investment Hedging [Member]
Derivative [Line Items]
Gains (losses) recognized in OCI on derivatives (effective portion)	0	(2)	(24)	(6)
Net Investment Hedging [Member] | Other income (loss), net [Member]
Derivative [Line Items]
Gains (losses) reclassified from AOCI into income (effective portion)	$ 0	$ 0	$ 0	$ 0