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. 26, 2013	Jan. 28, 2012	Jan. 26, 2013	Jan. 28, 2012
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	$ 12,098	$ 11,527	$ 23,974	$ 22,783
Service [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	2,661	2,409	5,240	4,713
Sales Revenue, Product Line [Member] | Switching [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	3,724	3,621	7,340	7,308
Sales Revenue, Product Line [Member] | Next Generation Networks [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	1,946	2,068	3,998	4,162
Sales Revenue, Product Line [Member] | Service Provider Video [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	1,220	1,014	2,368	1,897
Sales Revenue, Product Line [Member] | Collaboration [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	945	1,060	1,965	2,168
Sales Revenue, Product Line [Member] | Data Center [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	548	333	965	592
Sales Revenue, Product Line [Member] | Wireless [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	520	409	1,006	762
Sales Revenue, Product Line [Member] | Security [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	336	333	674	652
Sales Revenue, Product Line [Member] | Other Products [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	198	280	418	529
Sales Revenue, Product Line [Member] | Product [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	$ 9,437	$ 9,118	$ 18,734	$ 18,070