Derivative Instruments (Effect Of Derivative Instruments Designated As Cash Flow Hedges On Other Comprehensive Income And Consolidated Statements Of Operations Summary) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Oct. 25, 2014	Oct. 26, 2013
Derivatives designated as cash flow hedging instruments:
Derivative [Line Items]
GAINS (LOSSES) RECOGNIZED IN OCI ON DERIVATIVES FOR THE THREE MONTHS ENDED (EFFECTIVE PORTION)	$ (56)	$ 38
GAINS (LOSSES) RECLASSIFIED FROM AOCI INTO INCOME FOR THE THREE MONTHS ENDED (EFFECTIVE PORTION)	(4)	9
Derivatives designated as cash flow hedging instruments: | Foreign currency derivatives
Derivative [Line Items]
GAINS (LOSSES) RECOGNIZED IN OCI ON DERIVATIVES FOR THE THREE MONTHS ENDED (EFFECTIVE PORTION)	(56)	38
Derivatives designated as cash flow hedging instruments: | Foreign currency derivatives | Operating expenses
Derivative [Line Items]
GAINS (LOSSES) RECLASSIFIED FROM AOCI INTO INCOME FOR THE THREE MONTHS ENDED (EFFECTIVE PORTION)	(3)	7
Derivatives designated as cash flow hedging instruments: | Foreign currency derivatives | Cost of sales—service
Derivative [Line Items]
GAINS (LOSSES) RECLASSIFIED FROM AOCI INTO INCOME FOR THE THREE MONTHS ENDED (EFFECTIVE PORTION)	(1)	2
Derivatives designated as net investment hedging instruments: | Foreign currency derivatives
Derivative [Line Items]
GAINS (LOSSES) RECOGNIZED IN OCI ON DERIVATIVES FOR THE THREE MONTHS ENDED (EFFECTIVE PORTION)	20	(19)
Derivatives designated as net investment hedging instruments: | Foreign currency derivatives | Other income (loss), net
Derivative [Line Items]
GAINS (LOSSES) RECLASSIFIED FROM AOCI INTO INCOME FOR THE THREE MONTHS ENDED (EFFECTIVE PORTION)	$ 0	$ 0