Segment Information and Major Customers (Summary Of Net Revenue For Groups Of Similar Products And Services) (Details) - USD ($) $ in Millions	3 Months Ended
	Oct. 29, 2016	Oct. 24, 2015
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue	$ 12,352	$ 12,682
Switching
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue	3,716	4,009
NGN Routing
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue	2,089	1,969
Collaboration
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue	1,081	1,115
Data Center
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue	834	859
Wireless
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue	632	646
Security
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue	540	485
Service Provider Video
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue	271	687
Other
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue	139	74
Product
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue	9,302	9,844
Service
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue	$ 3,050	2,838
SP Video CPE Business
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue		$ 411