Revenue - Disaggregation of Revenue (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jan. 29, 2022	Jan. 23, 2021	Jan. 29, 2022	Jan. 23, 2021
Disaggregation of Revenue [Line Items]
Revenue	$ 12,720	$ 11,960	$ 25,620	$ 23,889
Product
Disaggregation of Revenue [Line Items]
Revenue	9,353	8,572	18,882	17,159
Secure, Agile Networks
Disaggregation of Revenue [Line Items]
Revenue	5,898	5,489	11,866	10,923
Hybrid Work
Disaggregation of Revenue [Line Items]
Revenue	1,067	1,167	2,176	2,360
End-to-End Security
Disaggregation of Revenue [Line Items]
Revenue	883	822	1,778	1,684
Internet for the Future
Disaggregation of Revenue [Line Items]
Revenue	1,322	931	2,697	1,872
Optimized Application Experiences
Disaggregation of Revenue [Line Items]
Revenue	180	161	361	314
Other Products
Disaggregation of Revenue [Line Items]
Revenue	2	3	5	6
Services
Disaggregation of Revenue [Line Items]
Revenue	$ 3,367	$ 3,388	$ 6,738	$ 6,730