Goodwill and Purchased Intangible Assets (Schedule Of Intangible Assets Acquired Through Business Combinations) (Details) - USD ($) $ in Millions	12 Months Ended
	Jul. 30, 2016	Jul. 25, 2015	Jul. 26, 2014
Schedule of Finite Lived and Indefinite Lived Intangible Assets Acquired Through Business Combinations [Line Items]
Amount	$ 940	$ 99	$ 838
IPR&D
Schedule of Finite Lived and Indefinite Lived Intangible Assets Acquired Through Business Combinations [Line Items]
Amount	223	6
TECHNOLOGY
Schedule of Finite Lived and Indefinite Lived Intangible Assets Acquired Through Business Combinations [Line Items]
Amount	544	72
CUSTOMER RELATIONSHIPS
Schedule of Finite Lived and Indefinite Lived Intangible Assets Acquired Through Business Combinations [Line Items]
Amount	142	15
OTHER
Schedule of Finite Lived and Indefinite Lived Intangible Assets Acquired Through Business Combinations [Line Items]
Amount	31	6
MaintenanceNet
Schedule of Finite Lived and Indefinite Lived Intangible Assets Acquired Through Business Combinations [Line Items]
Amount	65
MaintenanceNet | IPR&D
Schedule of Finite Lived and Indefinite Lived Intangible Assets Acquired Through Business Combinations [Line Items]
Amount	$ 11
MaintenanceNet | TECHNOLOGY
Schedule of Finite Lived and Indefinite Lived Intangible Assets Acquired Through Business Combinations [Line Items]
Weighted- Average Useful Life (in Years)	5 years
Amount	$ 50
MaintenanceNet | CUSTOMER RELATIONSHIPS
Schedule of Finite Lived and Indefinite Lived Intangible Assets Acquired Through Business Combinations [Line Items]
Weighted- Average Useful Life (in Years)	5 years
Amount	$ 2
MaintenanceNet | OTHER
Schedule of Finite Lived and Indefinite Lived Intangible Assets Acquired Through Business Combinations [Line Items]
Weighted- Average Useful Life (in Years)	2 years
Amount	$ 2
OpenDNS
Schedule of Finite Lived and Indefinite Lived Intangible Assets Acquired Through Business Combinations [Line Items]
Amount	61
OpenDNS | IPR&D
Schedule of Finite Lived and Indefinite Lived Intangible Assets Acquired Through Business Combinations [Line Items]
Amount	$ 1
OpenDNS | TECHNOLOGY
Schedule of Finite Lived and Indefinite Lived Intangible Assets Acquired Through Business Combinations [Line Items]
Weighted- Average Useful Life (in Years)	5 years
Amount	$ 43
OpenDNS | CUSTOMER RELATIONSHIPS
Schedule of Finite Lived and Indefinite Lived Intangible Assets Acquired Through Business Combinations [Line Items]
Weighted- Average Useful Life (in Years)	7 years
Amount	$ 15
OpenDNS | OTHER
Schedule of Finite Lived and Indefinite Lived Intangible Assets Acquired Through Business Combinations [Line Items]
Weighted- Average Useful Life (in Years)	1 year
Amount	$ 2
Lancope
Schedule of Finite Lived and Indefinite Lived Intangible Assets Acquired Through Business Combinations [Line Items]
Amount	121
Lancope | IPR&D
Schedule of Finite Lived and Indefinite Lived Intangible Assets Acquired Through Business Combinations [Line Items]
Amount	$ 10
Lancope | TECHNOLOGY
Schedule of Finite Lived and Indefinite Lived Intangible Assets Acquired Through Business Combinations [Line Items]
Weighted- Average Useful Life (in Years)	5 years
Amount	$ 79
Lancope | CUSTOMER RELATIONSHIPS
Schedule of Finite Lived and Indefinite Lived Intangible Assets Acquired Through Business Combinations [Line Items]
Weighted- Average Useful Life (in Years)	6 years
Amount	$ 29
Lancope | OTHER
Schedule of Finite Lived and Indefinite Lived Intangible Assets Acquired Through Business Combinations [Line Items]
Weighted- Average Useful Life (in Years)	3 years
Amount	$ 3
Acano
Schedule of Finite Lived and Indefinite Lived Intangible Assets Acquired Through Business Combinations [Line Items]
Amount	103
Acano | IPR&D
Schedule of Finite Lived and Indefinite Lived Intangible Assets Acquired Through Business Combinations [Line Items]
Amount	$ 82
Acano | TECHNOLOGY
Schedule of Finite Lived and Indefinite Lived Intangible Assets Acquired Through Business Combinations [Line Items]
Weighted- Average Useful Life (in Years)	5 years
Amount	$ 9
Acano | CUSTOMER RELATIONSHIPS
Schedule of Finite Lived and Indefinite Lived Intangible Assets Acquired Through Business Combinations [Line Items]
Weighted- Average Useful Life (in Years)	5 years
Amount	$ 12
Acano | OTHER
Schedule of Finite Lived and Indefinite Lived Intangible Assets Acquired Through Business Combinations [Line Items]
Weighted- Average Useful Life (in Years)	0 years
Amount	$ 0
Leaba
Schedule of Finite Lived and Indefinite Lived Intangible Assets Acquired Through Business Combinations [Line Items]
Amount	96
Leaba | IPR&D
Schedule of Finite Lived and Indefinite Lived Intangible Assets Acquired Through Business Combinations [Line Items]
Amount	$ 96
Leaba | TECHNOLOGY
Schedule of Finite Lived and Indefinite Lived Intangible Assets Acquired Through Business Combinations [Line Items]
Weighted- Average Useful Life (in Years)	0 years
Amount	$ 0
Leaba | CUSTOMER RELATIONSHIPS
Schedule of Finite Lived and Indefinite Lived Intangible Assets Acquired Through Business Combinations [Line Items]
Weighted- Average Useful Life (in Years)	0 years
Amount	$ 0
Leaba | OTHER
Schedule of Finite Lived and Indefinite Lived Intangible Assets Acquired Through Business Combinations [Line Items]
Weighted- Average Useful Life (in Years)	0 years
Amount	$ 0
Jasper
Schedule of Finite Lived and Indefinite Lived Intangible Assets Acquired Through Business Combinations [Line Items]
Amount	361
Jasper | IPR&D
Schedule of Finite Lived and Indefinite Lived Intangible Assets Acquired Through Business Combinations [Line Items]
Amount	$ 23
Jasper | TECHNOLOGY
Schedule of Finite Lived and Indefinite Lived Intangible Assets Acquired Through Business Combinations [Line Items]
Weighted- Average Useful Life (in Years)	6 years
Amount	$ 240
Jasper | CUSTOMER RELATIONSHIPS
Schedule of Finite Lived and Indefinite Lived Intangible Assets Acquired Through Business Combinations [Line Items]
Weighted- Average Useful Life (in Years)	7 years
Amount	$ 75
Jasper | OTHER
Schedule of Finite Lived and Indefinite Lived Intangible Assets Acquired Through Business Combinations [Line Items]
Weighted- Average Useful Life (in Years)	2 years
Amount	$ 23
Cliqr
Schedule of Finite Lived and Indefinite Lived Intangible Assets Acquired Through Business Combinations [Line Items]
Amount	69
Cliqr | IPR&D
Schedule of Finite Lived and Indefinite Lived Intangible Assets Acquired Through Business Combinations [Line Items]
Amount	$ 0
Cliqr | TECHNOLOGY
Schedule of Finite Lived and Indefinite Lived Intangible Assets Acquired Through Business Combinations [Line Items]
Weighted- Average Useful Life (in Years)	6 years
Amount	$ 65
Cliqr | CUSTOMER RELATIONSHIPS
Schedule of Finite Lived and Indefinite Lived Intangible Assets Acquired Through Business Combinations [Line Items]
Weighted- Average Useful Life (in Years)	6 years
Amount	$ 3
Cliqr | OTHER
Schedule of Finite Lived and Indefinite Lived Intangible Assets Acquired Through Business Combinations [Line Items]
Weighted- Average Useful Life (in Years)	2 years
Amount	$ 1
Metacloud
Schedule of Finite Lived and Indefinite Lived Intangible Assets Acquired Through Business Combinations [Line Items]
Amount		29
Metacloud | IPR&D
Schedule of Finite Lived and Indefinite Lived Intangible Assets Acquired Through Business Combinations [Line Items]
Amount		$ 2
Metacloud | TECHNOLOGY
Schedule of Finite Lived and Indefinite Lived Intangible Assets Acquired Through Business Combinations [Line Items]
Weighted- Average Useful Life (in Years)		3 years
Amount		$ 24
Metacloud | CUSTOMER RELATIONSHIPS
Schedule of Finite Lived and Indefinite Lived Intangible Assets Acquired Through Business Combinations [Line Items]
Weighted- Average Useful Life (in Years)		5 years
Amount		$ 3
Metacloud | OTHER
Schedule of Finite Lived and Indefinite Lived Intangible Assets Acquired Through Business Combinations [Line Items]
Weighted- Average Useful Life (in Years)		0 years
Amount		$ 0
All others
Schedule of Finite Lived and Indefinite Lived Intangible Assets Acquired Through Business Combinations [Line Items]
Amount	64	70
All others | IPR&D
Schedule of Finite Lived and Indefinite Lived Intangible Assets Acquired Through Business Combinations [Line Items]
Amount	$ 0	$ 4
All others | TECHNOLOGY
Schedule of Finite Lived and Indefinite Lived Intangible Assets Acquired Through Business Combinations [Line Items]
Weighted- Average Useful Life (in Years)	4 years 1 month 6 days	4 years 8 months 12 days
Amount	$ 58	$ 48
All others | CUSTOMER RELATIONSHIPS
Schedule of Finite Lived and Indefinite Lived Intangible Assets Acquired Through Business Combinations [Line Items]
Weighted- Average Useful Life (in Years)	6 years 3 months 18 days	7 years 9 months 18 days
Amount	$ 6	$ 12
All others | OTHER
Schedule of Finite Lived and Indefinite Lived Intangible Assets Acquired Through Business Combinations [Line Items]
Weighted- Average Useful Life (in Years)	0 years	5 years 9 months 18 days
Amount	$ 0	$ 6
Total
Schedule of Finite Lived and Indefinite Lived Intangible Assets Acquired Through Business Combinations [Line Items]
Amount	$ 940	$ 99