Goodwill and Purchased Intangible Assets (Schedule of Intangible Assets Acquired Through Business Combinations) (Details) $ in Millions	12 Months Ended
	Jul. 28, 2018 USD ($) acquisition	Jul. 29, 2017 USD ($) acquisition	Jul. 30, 2016 acquisition
Schedule of Finite Lived and Indefinite Lived Intangible Assets Acquired Through Business Combinations [Line Items]
Finite and indefinite-lived intangible assets acquired (excluding goodwill)	$ 867	$ 878
Number of business combinations (acquisition) | acquisition	8		12
IPR&D
Schedule of Finite Lived and Indefinite Lived Intangible Assets Acquired Through Business Combinations [Line Items]
Indefinite-lived intangible assets acquired	$ 3
TECHNOLOGY
Schedule of Finite Lived and Indefinite Lived Intangible Assets Acquired Through Business Combinations [Line Items]
Finite lived intangible assets acquired	650	614
CUSTOMER RELATIONSHIPS
Schedule of Finite Lived and Indefinite Lived Intangible Assets Acquired Through Business Combinations [Line Items]
Finite lived intangible assets acquired	207	238
OTHER
Schedule of Finite Lived and Indefinite Lived Intangible Assets Acquired Through Business Combinations [Line Items]
Finite lived intangible assets acquired	7	26
Viptela
Schedule of Finite Lived and Indefinite Lived Intangible Assets Acquired Through Business Combinations [Line Items]
Finite and indefinite-lived intangible assets acquired (excluding goodwill)	$ 180
Viptela | TECHNOLOGY
Schedule of Finite Lived and Indefinite Lived Intangible Assets Acquired Through Business Combinations [Line Items]
Weighted- Average Useful Life (in Years)	5 years
Finite lived intangible assets acquired	$ 144
Viptela | 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
Finite lived intangible assets acquired	$ 35
Viptela | OTHER
Schedule of Finite Lived and Indefinite Lived Intangible Assets Acquired Through Business Combinations [Line Items]
Weighted- Average Useful Life (in Years)	1 year
Finite lived intangible assets acquired	$ 1
Springpath
Schedule of Finite Lived and Indefinite Lived Intangible Assets Acquired Through Business Combinations [Line Items]
Finite and indefinite-lived intangible assets acquired (excluding goodwill)	160
Springpath | IPR&D
Schedule of Finite Lived and Indefinite Lived Intangible Assets Acquired Through Business Combinations [Line Items]
Indefinite-lived intangible assets acquired	$ 3
Springpath | TECHNOLOGY
Schedule of Finite Lived and Indefinite Lived Intangible Assets Acquired Through Business Combinations [Line Items]
Weighted- Average Useful Life (in Years)	4 years
Finite lived intangible assets acquired	$ 157
BroadSoft
Schedule of Finite Lived and Indefinite Lived Intangible Assets Acquired Through Business Combinations [Line Items]
Finite and indefinite-lived intangible assets acquired (excluding goodwill)	$ 430
BroadSoft | TECHNOLOGY
Schedule of Finite Lived and Indefinite Lived Intangible Assets Acquired Through Business Combinations [Line Items]
Weighted- Average Useful Life (in Years)	4 years
Finite lived intangible assets acquired	$ 255
BroadSoft | 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
Finite lived intangible assets acquired	$ 169
BroadSoft | OTHER
Schedule of Finite Lived and Indefinite Lived Intangible Assets Acquired Through Business Combinations [Line Items]
Weighted- Average Useful Life (in Years)	2 years
Finite lived intangible assets acquired	$ 6
Accompany
Schedule of Finite Lived and Indefinite Lived Intangible Assets Acquired Through Business Combinations [Line Items]
Finite and indefinite-lived intangible assets acquired (excluding goodwill)	$ 55
Accompany | TECHNOLOGY
Schedule of Finite Lived and Indefinite Lived Intangible Assets Acquired Through Business Combinations [Line Items]
Weighted- Average Useful Life (in Years)	4 years
Finite lived intangible assets acquired	$ 55
CloudLock
Schedule of Finite Lived and Indefinite Lived Intangible Assets Acquired Through Business Combinations [Line Items]
Finite and indefinite-lived intangible assets acquired (excluding goodwill)		$ 36
CloudLock | TECHNOLOGY
Schedule of Finite Lived and Indefinite Lived Intangible Assets Acquired Through Business Combinations [Line Items]
Weighted- Average Useful Life (in Years)		6 years
Finite lived intangible assets acquired		$ 32
CloudLock | CUSTOMER RELATIONSHIPS
Schedule of Finite Lived and Indefinite Lived Intangible Assets Acquired Through Business Combinations [Line Items]
Weighted- Average Useful Life (in Years)		4 years
Finite lived intangible assets acquired		$ 3
CloudLock | OTHER
Schedule of Finite Lived and Indefinite Lived Intangible Assets Acquired Through Business Combinations [Line Items]
Weighted- Average Useful Life (in Years)		1 year 6 months
Finite lived intangible assets acquired		$ 1
AppDynamics
Schedule of Finite Lived and Indefinite Lived Intangible Assets Acquired Through Business Combinations [Line Items]
Finite and indefinite-lived intangible assets acquired (excluding goodwill)		$ 785
AppDynamics | TECHNOLOGY
Schedule of Finite Lived and Indefinite Lived Intangible Assets Acquired Through Business Combinations [Line Items]
Weighted- Average Useful Life (in Years)		4 years
Finite lived intangible assets acquired		$ 525
AppDynamics | 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
Finite lived intangible assets acquired		$ 235
AppDynamics | OTHER
Schedule of Finite Lived and Indefinite Lived Intangible Assets Acquired Through Business Combinations [Line Items]
Weighted- Average Useful Life (in Years)		2 years 3 months 18 days
Finite lived intangible assets acquired		$ 25
MindMeld
Schedule of Finite Lived and Indefinite Lived Intangible Assets Acquired Through Business Combinations [Line Items]
Finite and indefinite-lived intangible assets acquired (excluding goodwill)		$ 51
MindMeld | TECHNOLOGY
Schedule of Finite Lived and Indefinite Lived Intangible Assets Acquired Through Business Combinations [Line Items]
Weighted- Average Useful Life (in Years)		4 years
Finite lived intangible assets acquired		$ 51
MindMeld | CUSTOMER RELATIONSHIPS
Schedule of Finite Lived and Indefinite Lived Intangible Assets Acquired Through Business Combinations [Line Items]
Weighted- Average Useful Life (in Years)		1 year
Finite lived intangible assets acquired		$ 0
Others
Schedule of Finite Lived and Indefinite Lived Intangible Assets Acquired Through Business Combinations [Line Items]
Finite and indefinite-lived intangible assets acquired (excluding goodwill)	$ 42	$ 6
Number of business combinations (acquisition) | acquisition	4	4
Others | TECHNOLOGY
Schedule of Finite Lived and Indefinite Lived Intangible Assets Acquired Through Business Combinations [Line Items]
Weighted- Average Useful Life (in Years)	3 years 10 months 23 days	3 years
Finite lived intangible assets acquired	$ 39	$ 6
Others | CUSTOMER RELATIONSHIPS
Schedule of Finite Lived and Indefinite Lived Intangible Assets Acquired Through Business Combinations [Line Items]
Weighted- Average Useful Life (in Years)	4 years
Finite lived intangible assets acquired	$ 3