Acquisitions and Divestitures (Summary Of Allocation Of Total Purchase Consideration) (Details) $ in Millions	3 Months Ended
	Oct. 28, 2017 USD ($)
Business Acquisition [Line Items]
Purchase Consideration	$ 761
Net Tangible Assets Acquired (Liabilities Assumed)	(28)
Purchased Intangible Assets	346
Goodwill	443
Viptela
Business Acquisition [Line Items]
Purchase Consideration	497
Net Tangible Assets Acquired (Liabilities Assumed)	(18)
Purchased Intangible Assets	180
Goodwill	335
Springpath
Business Acquisition [Line Items]
Purchase Consideration	248
Net Tangible Assets Acquired (Liabilities Assumed)	(11)
Purchased Intangible Assets	160
Goodwill	99
Other
Business Acquisition [Line Items]
Purchase Consideration	16
Net Tangible Assets Acquired (Liabilities Assumed)	1
Purchased Intangible Assets	6
Goodwill	$ 9