Acquisitions and Divestitures (Summary Of Allocation Of Total Purchase Consideration) (Details) $ in Millions	6 Months Ended
	Jan. 23, 2016 USD ($) acquisitions
Business Acquisition [Line Items]
Number of business combinations (in numbers) | acquisitions	7
Purchase Consideration	$ 1,168
Net Liabilities Assumed	(81)
Purchased Intangible Assets	309
Goodwill	940
MaintenanceNet
Business Acquisition [Line Items]
Purchase Consideration	105
Net Liabilities Assumed	(21)
Purchased Intangible Assets	65
Goodwill	61
OpenDNS
Business Acquisition [Line Items]
Purchase Consideration	545
Net Liabilities Assumed	(9)
Purchased Intangible Assets	61
Goodwill	493
Lancope
Business Acquisition [Line Items]
Purchase Consideration	410
Net Liabilities Assumed	(34)
Purchased Intangible Assets	121
Goodwill	$ 323
Others (four in total)
Business Acquisition [Line Items]
Number of business combinations (in numbers)	4
Purchase Consideration	$ 108
Net Liabilities Assumed	(17)
Purchased Intangible Assets	62
Goodwill	$ 63