Revenue - Disaggregation of Revenue (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Jul. 25, 2020	Apr. 25, 2020	Jan. 25, 2020	Oct. 26, 2019	Jul. 27, 2019	Apr. 27, 2019	Jan. 26, 2019	Oct. 27, 2018	Jul. 25, 2020	Jul. 27, 2019	Jul. 28, 2018
Disaggregation of Revenue [Line Items]
Revenue	$ 12,154	$ 11,983	$ 12,005	$ 13,159	$ 13,428	$ 12,958	$ 12,446	$ 13,072	$ 49,301	$ 51,904	$ 49,330
Disposed of by sale | SPVSS Business
Disaggregation of Revenue [Line Items]
Revenue										168	903
Product
Disaggregation of Revenue [Line Items]
Revenue									35,978	39,005	36,709
Infrastructure Platforms
Disaggregation of Revenue [Line Items]
Revenue									27,122	30,099	28,286
Applications
Disaggregation of Revenue [Line Items]
Revenue									5,568	5,803	5,036
Security
Disaggregation of Revenue [Line Items]
Revenue									3,154	2,821	2,388
Other Products
Disaggregation of Revenue [Line Items]
Revenue									135	281	999
Service
Disaggregation of Revenue [Line Items]
Revenue									$ 13,323	$ 12,899	$ 12,621