Acquisitions and Divestitures (Additional Information) (Details) $ in Millions	12 Months Ended
	Jul. 30, 2016 USD ($)	Jul. 25, 2015 USD ($)	Jul. 26, 2014 USD ($)
Business Acquisition [Line Items]
Number of business combinations (in numbers)	12
Acquired Cash and Cash Equivalents	$ 44	$ 5	$ 134
General and Administrative Expense [Member]
Business Acquisition [Line Items]
Business Acquisition, Transaction Costs	$ 32	$ 10	$ 7
MaintenanceNet
Business Acquisition [Line Items]
Business Acquisition, Effective Date of Acquisition	Aug. 06, 2015
OpenDNS
Business Acquisition [Line Items]
Business Acquisition, Effective Date of Acquisition	Aug. 26, 2015
Lancope
Business Acquisition [Line Items]
Business Acquisition, Effective Date of Acquisition	Dec. 21, 2015
Acano
Business Acquisition [Line Items]
Business Acquisition, Effective Date of Acquisition	Jan. 29, 2016
Leaba
Business Acquisition [Line Items]
Business Acquisition, Effective Date of Acquisition	Mar. 03, 2016
Jasper
Business Acquisition [Line Items]
Business Acquisition, Effective Date of Acquisition	Mar. 18, 2016
Cliqr
Business Acquisition [Line Items]
Business Acquisition, Effective Date of Acquisition	Apr. 15, 2016