Segment Information And Major Customers (Summary Of Net Sales For Groups Of Similar Products And Services) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Apr. 28, 2012	Apr. 30, 2011	Apr. 28, 2012	Apr. 30, 2011
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales	$ 11,588	$ 10,866	$ 34,371	$ 32,023
Service [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales	2,482	2,197	7,195	6,418
Sales Revenue, Product Line [Member] | Switching [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales	3,644	3,480	10,926	10,510
Sales Revenue, Product Line [Member] | NGN Routing [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales	2,143	2,150	6,328	6,246
Sales Revenue, Product Line [Member] | Collaboration [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales	1,007	1,008	3,147	2,937
Sales Revenue, Product Line [Member] | Service Provider Video [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales	1,002	898	2,896	2,501
Sales Revenue, Product Line [Member] | Wireless [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales	425	353	1,205	1,022
Sales Revenue, Product Line [Member] | Security [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales	345	316	999	876
Sales Revenue, Product Line [Member] | Data Center [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales	291	173	883	475
Sales Revenue, Product Line [Member] | Other Products [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales	249	291	792	1,038
Sales Revenue, Product Line [Member] | Product [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales	$ 9,106	$ 8,669	$ 27,176	$ 25,605