Goodwill and Purchased Intangible Assets (Schedule Of Intangible Assets Acquired Through Business Combinations) (Details) $ in Millions	9 Months Ended
	Apr. 30, 2016 USD ($)
Intangible Assets Acquired Through Business Combinations
Amount	$ 940
MaintenanceNet
Intangible Assets Acquired Through Business Combinations
Amount	65
OpenDNS
Intangible Assets Acquired Through Business Combinations
Amount	61
Lancope
Intangible Assets Acquired Through Business Combinations
Amount	121
Acano
Intangible Assets Acquired Through Business Combinations
Amount	103
Leaba
Intangible Assets Acquired Through Business Combinations
Amount	96
Jasper
Intangible Assets Acquired Through Business Combinations
Amount	361
CliQr
Intangible Assets Acquired Through Business Combinations
Amount	69
Others (five in total)
Intangible Assets Acquired Through Business Combinations
Amount	64
Total
Intangible Assets Acquired Through Business Combinations
Amount	940
IPR&D
Intangible Assets Acquired Through Business Combinations
Amount	223
IPR&D | MaintenanceNet
Intangible Assets Acquired Through Business Combinations
Amount	11
IPR&D | OpenDNS
Intangible Assets Acquired Through Business Combinations
Amount	1
IPR&D | Lancope
Intangible Assets Acquired Through Business Combinations
Amount	10
IPR&D | Acano
Intangible Assets Acquired Through Business Combinations
Amount	82
IPR&D | Leaba
Intangible Assets Acquired Through Business Combinations
Amount	96
IPR&D | Jasper
Intangible Assets Acquired Through Business Combinations
Amount	23
IPR&D | CliQr
Intangible Assets Acquired Through Business Combinations
Amount	0
IPR&D | Others (five in total)
Intangible Assets Acquired Through Business Combinations
Amount	0
TECHNOLOGY
Intangible Assets Acquired Through Business Combinations
Amount	$ 544
TECHNOLOGY | MaintenanceNet
Intangible Assets Acquired Through Business Combinations
Weighted- Average Useful Life (in Years)	5 years
Amount	$ 50
TECHNOLOGY | OpenDNS
Intangible Assets Acquired Through Business Combinations
Weighted- Average Useful Life (in Years)	5 years
Amount	$ 43
TECHNOLOGY | Lancope
Intangible Assets Acquired Through Business Combinations
Weighted- Average Useful Life (in Years)	5 years
Amount	$ 79
TECHNOLOGY | Acano
Intangible Assets Acquired Through Business Combinations
Weighted- Average Useful Life (in Years)	5 years
Amount	$ 9
TECHNOLOGY | Leaba
Intangible Assets Acquired Through Business Combinations
Weighted- Average Useful Life (in Years)	0 years
Amount	$ 0
TECHNOLOGY | Jasper
Intangible Assets Acquired Through Business Combinations
Weighted- Average Useful Life (in Years)	6 years
Amount	$ 240
TECHNOLOGY | CliQr
Intangible Assets Acquired Through Business Combinations
Weighted- Average Useful Life (in Years)	6 years
Amount	$ 65
TECHNOLOGY | Others (five in total)
Intangible Assets Acquired Through Business Combinations
Weighted- Average Useful Life (in Years)	4 years 1 month 6 days
Amount	$ 58
CUSTOMER RELATIONSHIPS
Intangible Assets Acquired Through Business Combinations
Amount	$ 142
CUSTOMER RELATIONSHIPS | MaintenanceNet
Intangible Assets Acquired Through Business Combinations
Weighted- Average Useful Life (in Years)	5 years
Amount	$ 2
CUSTOMER RELATIONSHIPS | OpenDNS
Intangible Assets Acquired Through Business Combinations
Weighted- Average Useful Life (in Years)	7 years
Amount	$ 15
CUSTOMER RELATIONSHIPS | Lancope
Intangible Assets Acquired Through Business Combinations
Weighted- Average Useful Life (in Years)	6 years
Amount	$ 29
CUSTOMER RELATIONSHIPS | Acano
Intangible Assets Acquired Through Business Combinations
Weighted- Average Useful Life (in Years)	5 years
Amount	$ 12
CUSTOMER RELATIONSHIPS | Leaba
Intangible Assets Acquired Through Business Combinations
Weighted- Average Useful Life (in Years)	0 years
Amount	$ 0
CUSTOMER RELATIONSHIPS | Jasper
Intangible Assets Acquired Through Business Combinations
Weighted- Average Useful Life (in Years)	7 years
Amount	$ 75
CUSTOMER RELATIONSHIPS | CliQr
Intangible Assets Acquired Through Business Combinations
Weighted- Average Useful Life (in Years)	6 years
Amount	$ 3
CUSTOMER RELATIONSHIPS | Others (five in total)
Intangible Assets Acquired Through Business Combinations
Weighted- Average Useful Life (in Years)	6 years 3 months 18 days
Amount	$ 6
OTHER
Intangible Assets Acquired Through Business Combinations
Amount	$ 31
OTHER | MaintenanceNet
Intangible Assets Acquired Through Business Combinations
Weighted- Average Useful Life (in Years)	2 years
Amount	$ 2
OTHER | OpenDNS
Intangible Assets Acquired Through Business Combinations
Weighted- Average Useful Life (in Years)	1 year
Amount	$ 2
OTHER | Lancope
Intangible Assets Acquired Through Business Combinations
Weighted- Average Useful Life (in Years)	3 years
Amount	$ 3
OTHER | Acano
Intangible Assets Acquired Through Business Combinations
Weighted- Average Useful Life (in Years)	0 years
Amount	$ 0
OTHER | Leaba
Intangible Assets Acquired Through Business Combinations
Weighted- Average Useful Life (in Years)	0 years
Amount	$ 0
OTHER | Jasper
Intangible Assets Acquired Through Business Combinations
Weighted- Average Useful Life (in Years)	2 years
Amount	$ 23
OTHER | CliQr
Intangible Assets Acquired Through Business Combinations
Weighted- Average Useful Life (in Years)	2 years
Amount	$ 1
OTHER | Others (five in total)
Intangible Assets Acquired Through Business Combinations
Weighted- Average Useful Life (in Years)	0 years
Amount	$ 0