Segment Information and Major Customers (Summary Of Net Revenue For Groups Of Similar Products And Services) (Details) - USD ($) $ in Millions	3 Months Ended
	Oct. 24, 2015	Oct. 25, 2014
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue	$ 12,682	$ 12,245
Switching
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue	4,022	3,846
NGN Routing
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue	1,793	1,949
Collaboration
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue	1,115	950
Data Center
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue	859	692
Service Provider Video
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue	850	871
Wireless
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue	645	605
Security
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue	485	455
Other
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue	75	67
Product
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue	9,844	9,435
Service
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue	$ 2,838	$ 2,810