Revenue (Disaggregation of Revenue) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Apr. 27, 2019	Apr. 28, 2018	Apr. 27, 2019	Apr. 28, 2018
Disaggregation of Revenue [Line Items]
Revenue	$ 12,958	$ 12,463	$ 38,476	$ 36,486
Product
Disaggregation of Revenue [Line Items]
Revenue	9,722	9,304	28,885	27,067
Infrastructure Platforms
Disaggregation of Revenue [Line Items]
Revenue	7,545	7,180	22,315	20,870
Applications
Disaggregation of Revenue [Line Items]
Revenue	1,431	1,310	4,315	3,697
Security
Disaggregation of Revenue [Line Items]
Revenue	707	583	2,016	1,725
Other Products
Disaggregation of Revenue [Line Items]
Revenue	39	231	239	775
Other Products | Discontinued operations, held-for-sale | Service Provider Video
Disaggregation of Revenue [Line Items]
Revenue	0	219	168	697
Service
Disaggregation of Revenue [Line Items]
Revenue	$ 3,236	$ 3,159	$ 9,591	$ 9,419