Summary of Significant Accounting Policies (Additional Information) (Details) $ in Millions	12 Months Ended
	Jul. 25, 2015 USD ($) Rating	Jul. 26, 2014 USD ($)	Jul. 27, 2013 USD ($)
Summary Of Significant Accounting Policies [Line Items]
Average lease term (in years)	4 years
Investment Credit Risk Ratings Range Lowest (credit risk rating)	1
Investment Credit Risk Ratings Range Highest (credit risk rating)	10
Rating at or higher when receivables deemed impaired (credit risk rating)	8
Threshold for past due receivables (in days)	31 days
Threshold for not accruing interest (in days)	90 days
Depreciation, Depletion and Amortization | $	$ 1,100	$ 1,200	$ 1,200
Advertising costs | $	$ 202	196	$ 218
Minimum
Summary Of Significant Accounting Policies [Line Items]
Financed service contracts term (in years)	1 year
Channel partners revolving short-term financing payment term	60 days
Maximum
Summary Of Significant Accounting Policies [Line Items]
Loan receivables term (in years)	3 years
Financed service contracts term (in years)	3 years
Channel partners revolving short-term financing payment term	90 days
End User Lease And Loan Term	3 years
Technical support services [Member] | Minimum
Summary Of Significant Accounting Policies [Line Items]
Deferred revenue recognition period	1 year
Technical support services [Member] | Maximum
Summary Of Significant Accounting Policies [Line Items]
Deferred revenue recognition period	3 years
Estimated accruals for rebates, cooperative marketing and other programs with distributors and partners [Member]
Summary Of Significant Accounting Policies [Line Items]
Other Accrued Liabilities, Current | $	$ 1,300	$ 1,300