Segment Information and Major Customers (Summary of Net Revenue for Groups of Similar Products and Services) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Jul. 29, 2017	Apr. 29, 2017	Jan. 28, 2017	Oct. 29, 2016	Jul. 30, 2016	Apr. 30, 2016	Jan. 23, 2016	Oct. 24, 2015	Jul. 29, 2017	Jul. 30, 2016	Jul. 25, 2015
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue	$ 12,133	$ 11,940	$ 11,580	$ 12,352	$ 12,638	$ 12,000	$ 11,927	$ 12,682	$ 48,005	$ 49,247	$ 49,161
Switching
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue									13,949	14,700	14,712
NGN Routing
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue									7,831	8,133	8,343
Collaboration
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue									4,278	4,352	4,004
Data Center
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue									3,228	3,365	3,219
Wireless
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue									2,766	2,640	2,551
Security
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue									2,153	1,969	1,747
Service Provider Video
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue									946	1,734	2,941
Other
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue									554	361	233
Product:
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue									35,705	37,254	37,750
Service
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue									$ 12,300	11,993	11,411
SP Video CPE Business
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue										$ 504	$ 1,846