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		6 Months Ended
	Jan. 25, 2014	Jan. 26, 2013	Jan. 25, 2014	Jan. 26, 2013
Cash Flow Hedging
Derivative [Line Items]
Gains (losses) recognized in OCI on derivatives (effective portion)	$ (4)	$ 3	$ 34	$ 69
Gains (losses) reclassified from AOCI into income (effective portion)	19	8	28	3
Cash Flow Hedging | Foreign Currency Derivatives
Derivative [Line Items]
Gains (losses) recognized in OCI on derivatives (effective portion)	(4)	3	34	69
Cash Flow Hedging | Foreign Currency Derivatives | Operating Expenses
Derivative [Line Items]
Gains (losses) reclassified from AOCI into income (effective portion)	16	6	23	2
Cash Flow Hedging | Foreign Currency Derivatives | Cost Of Sales-Service
Derivative [Line Items]
Gains (losses) reclassified from AOCI into income (effective portion)	3	2	5	1
Net Investment Hedging
Derivative [Line Items]
Gains (losses) recognized in OCI on derivatives (effective portion)	16	0	(3)	(24)
Net Investment Hedging | Other income (loss), net
Derivative [Line Items]
Gains (losses) reclassified from AOCI into income (effective portion)	$ 0	$ 0	$ 0	$ 0