Segment Information and Major Customers (Summary Of Net Revenue For Groups Of Similar Products And Services) (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Apr. 30, 2016	Apr. 25, 2015	Apr. 30, 2016	Apr. 25, 2015
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue		$ 12,000	$ 12,137	$ 36,609	$ 36,318
Switching
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue		3,447	3,560	10,952	11,021
NGN Routing
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue		1,894	1,999	5,532	5,712
Collaboration
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue		1,069	974	3,203	2,915
Data Center
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue		811	801	2,492	2,339
Service Provider Video (1)
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue	[1]	468	914	1,980	2,561
Wireless
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue		615	611	1,873	1,827
Security
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue		482	412	1,429	1,283
Other
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue		89	55	241	181
Product
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue		8,875	9,326	27,702	27,839
Service
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue		$ 3,125	$ 2,811	$ 8,907	$ 8,479

[1] SP Video CPE Business revenue of zero and $519 million for the third quarters of fiscal 2016 and 2015, respectively and $504 million and $1,359 million for the first nine months of fiscal 2016 and 2015, respectively.