Goodwill and Purchased Intangible Assets (Schedule of Intangible Assets Acquired Through Business Combinations) (Details) $ in Millions	9 Months Ended
	Apr. 28, 2018 USD ($) acquisition
Intangible Assets Acquired Through Business Combinations
Total, Amount	$ 812
Number of business combinations (acquisition) | acquisition	7
Viptela
Intangible Assets Acquired Through Business Combinations
Total, Amount	$ 180
Springpath
Intangible Assets Acquired Through Business Combinations
Total, Amount	160
BroadSoft
Intangible Assets Acquired Through Business Combinations
Total, Amount	430
Others (four in total)
Intangible Assets Acquired Through Business Combinations
Total, Amount	$ 42
Number of business combinations (acquisition) | acquisition	4
IPR&D
Intangible Assets Acquired Through Business Combinations
Indefinite Lives, Amount	$ 3
IPR&D | Viptela
Intangible Assets Acquired Through Business Combinations
Indefinite Lives, Amount	0
IPR&D | Springpath
Intangible Assets Acquired Through Business Combinations
Indefinite Lives, Amount	3
IPR&D | BroadSoft
Intangible Assets Acquired Through Business Combinations
Indefinite Lives, Amount	0
IPR&D | Others (four in total)
Intangible Assets Acquired Through Business Combinations
Indefinite Lives, Amount	0
TECHNOLOGY
Intangible Assets Acquired Through Business Combinations
Finite Lives, Amount	$ 595
TECHNOLOGY | Viptela
Intangible Assets Acquired Through Business Combinations
Weighted- Average Useful Life (in Years)	5 years
Finite Lives, Amount	$ 144
TECHNOLOGY | Springpath
Intangible Assets Acquired Through Business Combinations
Weighted- Average Useful Life (in Years)	4 years
Finite Lives, Amount	$ 157
TECHNOLOGY | BroadSoft
Intangible Assets Acquired Through Business Combinations
Weighted- Average Useful Life (in Years)	4 years
Finite Lives, Amount	$ 255
TECHNOLOGY | Others (four in total)
Intangible Assets Acquired Through Business Combinations
Weighted- Average Useful Life (in Years)	3 years 10 months 24 days
Finite Lives, Amount	$ 39
CUSTOMER RELATIONSHIPS
Intangible Assets Acquired Through Business Combinations
Finite Lives, Amount	$ 207
CUSTOMER RELATIONSHIPS | Viptela
Intangible Assets Acquired Through Business Combinations
Weighted- Average Useful Life (in Years)	6 years
Finite Lives, Amount	$ 35
CUSTOMER RELATIONSHIPS | Springpath
Intangible Assets Acquired Through Business Combinations
Weighted- Average Useful Life (in Years)	0 years
Finite Lives, Amount	$ 0
CUSTOMER RELATIONSHIPS | BroadSoft
Intangible Assets Acquired Through Business Combinations
Weighted- Average Useful Life (in Years)	6 years
Finite Lives, Amount	$ 169
CUSTOMER RELATIONSHIPS | Others (four in total)
Intangible Assets Acquired Through Business Combinations
Weighted- Average Useful Life (in Years)	4 years
Finite Lives, Amount	$ 3
OTHER
Intangible Assets Acquired Through Business Combinations
Finite Lives, Amount	$ 7
OTHER | Viptela
Intangible Assets Acquired Through Business Combinations
Weighted- Average Useful Life (in Years)	1 year
Finite Lives, Amount	$ 1
OTHER | Springpath
Intangible Assets Acquired Through Business Combinations
Weighted- Average Useful Life (in Years)	0 years
Finite Lives, Amount	$ 0
OTHER | BroadSoft
Intangible Assets Acquired Through Business Combinations
Weighted- Average Useful Life (in Years)	2 years
Finite Lives, Amount	$ 6
OTHER | Others (four in total)
Intangible Assets Acquired Through Business Combinations
Weighted- Average Useful Life (in Years)	0 years
Finite Lives, Amount	$ 0