Segment Information And Major Customers (Net Sales For Groups Of Similar Products And Services) (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Oct. 26, 2013	Oct. 27, 2012
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	$ 12,085	$ 11,876
Switching
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	3,754	3,629
NGN Routing
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	2,043	2,055
Collaboration
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	1,027	1,020
Service Provider Video
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	987	1,149
Data Center [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	601	417
Wireless [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	540	499
Security [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	365	338
Other Products [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	80	190
Product [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	9,397	9,297
Service [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	$ 2,688	$ 2,579