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	12 Months Ended
	Jul. 28, 2018	Jul. 29, 2017	Jul. 30, 2016
Derivatives designated as cash flow hedging instruments:
Derivative [Line Items]
GAINS (LOSSES) RECOGNIZED IN OCI ON DERIVATIVES FOR THE YEARS ENDED (EFFECTIVE PORTION)	$ 20	$ 22	$ (66)
GAINS (LOSSES) RECLASSIFIED FROM AOCI INTO INCOME FOR THE YEARS ENDED (EFFECTIVE PORTION)	68	(79)	(20)
Derivatives designated as cash flow hedging instruments: | Foreign currency derivatives
Derivative [Line Items]
GAINS (LOSSES) RECOGNIZED IN OCI ON DERIVATIVES FOR THE YEARS ENDED (EFFECTIVE PORTION)	20	22	(66)
Derivatives designated as cash flow hedging instruments: | Foreign currency derivatives | Operating expenses
Derivative [Line Items]
GAINS (LOSSES) RECLASSIFIED FROM AOCI INTO INCOME FOR THE YEARS ENDED (EFFECTIVE PORTION)	52	(59)	(15)
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 YEARS ENDED (EFFECTIVE PORTION)	16	(20)	(5)
Derivatives designated as net investment hedging instruments: | Foreign currency derivatives
Derivative [Line Items]
GAINS (LOSSES) RECOGNIZED IN OCI ON DERIVATIVES FOR THE YEARS ENDED (EFFECTIVE PORTION)	(1)	(15)	16
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 YEARS ENDED (EFFECTIVE PORTION)	$ 0	$ 0	$ 0