Segment Information And Major Customers (Net Sales For Groups Of Similar Products And Services) (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jan. 25, 2014	Jan. 26, 2013	Jan. 25, 2014	Jan. 26, 2013
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	$ 11,155	$ 12,098	$ 23,240	$ 23,974
Switching
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	3,271	3,732	7,025	7,361
NGN Routing
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	1,741	1,947	3,784	4,002
Service Provider Video
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	957	1,222	1,944	2,371
Collaboration
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	881	945	1,908	1,965
Data Center
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	605	548	1,206	965
Wireless
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	511	535	1,051	1,034
Security
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	393	337	758	675
Other Products
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	64	171	144	361
Product
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	8,423	9,437	17,820	18,734
Service
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	$ 2,732	$ 2,661	$ 5,420	$ 5,240