Segment Information and Major Customers - Summary of Net Revenue for Groups of Similar Products and Services (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Apr. 25, 2020	Apr. 27, 2019	Apr. 25, 2020	Apr. 27, 2019
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue, total	$ 11,983	$ 12,958	$ 37,147	$ 38,476
Discontinued operations, held-for-sale | Service Provider Video
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue, total				168
Total Product
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue, total	8,597	9,722	27,146	28,885
Infrastructure Platforms
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue, total	6,429	7,523	20,496	22,247
Applications
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue, total	1,363	1,431	4,211	4,315
Security
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue, total	776	729	2,340	2,083
Other Products
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue, total	28	39	100	239
Service
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue, total	$ 3,386	$ 3,236	$ 10,001	$ 9,591