Business Combinations (Summary Of Allocation Of Total Purchase Consideration) (Detail) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Apr. 26, 2014
Business Acquisition [Line Items]
Purchase consideration	$ 2,970
Net Tangible Assets Acquired (Liabilities Assumed)	35
Purchased Intangible Assets	763
Goodwill	2,172
Composite Software, Inc.
Business Acquisition [Line Items]
Purchase consideration	160
Net Tangible Assets Acquired (Liabilities Assumed)	(10)
Purchased Intangible Assets	75
Goodwill	95
Sourcefire, Inc.
Business Acquisition [Line Items]
Purchase consideration	2,449
Net Tangible Assets Acquired (Liabilities Assumed)	81
Purchased Intangible Assets	577
Goodwill	1,791
WhipTail Technologies, Inc.
Business Acquisition [Line Items]
Purchase consideration	351
Net Tangible Assets Acquired (Liabilities Assumed)	(34)
Purchased Intangible Assets	105
Goodwill	280
Other Acquisitions
Business Acquisition [Line Items]
Purchase consideration	10
Net Tangible Assets Acquired (Liabilities Assumed)	(2)
Purchased Intangible Assets	6
Goodwill	$ 6