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		6 Months Ended
	Jan. 24, 2015	Jan. 25, 2014	Jan. 24, 2015	Jan. 25, 2014
Derivatives designated as cash flow hedging instruments:
Derivative [Line Items]
GAINS (LOSSES) RECOGNIZED IN OCI ON DERIVATIVES FOR THE THREE MONTHS ENDED (EFFECTIVE PORTION)	$ (75)	$ (4)	$ (131)	$ 34
GAINS (LOSSES) RECLASSIFIED FROM AOCI INTO INCOME FOR THE THREE MONTHS ENDED (EFFECTIVE PORTION)	(26)	19	(30)	28
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)	(75)	(4)	(131)	34
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)	(21)	16	(24)	23
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)	(5)	3	(6)	5
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)	24	16	44	(3)
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	$ 0	$ 0