Segment Information and Major Customers (Summary Of Net Revenue For Groups Of Similar Products And Services) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jan. 24, 2015	Jan. 25, 2014	Jan. 24, 2015	Jan. 25, 2014
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue	$ 11,936	$ 11,155	$ 24,181	$ 23,240
Switching
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue	3,616	3,258	7,462	6,998
NGN Routing
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue	1,764	1,730	3,713	3,756
Collaboration
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue	990	899	1,939	1,950
Service Provider Video
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue	776	957	1,647	1,944
Data Center
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue	846	605	1,539	1,206
Wireless
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue	611	517	1,216	1,064
Security
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue	416	393	871	758
Other
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue	59	64	126	144
Product:
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue	9,078	8,423	18,513	17,820
Service
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue	$ 2,858	$ 2,732	$ 5,668	$ 5,420