Revenue - Disaggregation of Revenue (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jan. 25, 2025	Jan. 27, 2024	Jan. 25, 2025	Jan. 27, 2024
Disaggregation of Revenue [Line Items]
Revenue	$ 13,991	$ 12,791	$ 27,832	$ 27,459
Product
Disaggregation of Revenue [Line Items]
Revenue	10,234	9,232	20,348	20,371
Networking
Disaggregation of Revenue [Line Items]
Revenue	6,850	7,081	13,603	15,904
Security
Disaggregation of Revenue [Line Items]
Revenue	2,111	973	4,129	1,984
Collaboration
Disaggregation of Revenue [Line Items]
Revenue	996	989	2,081	2,106
Observability
Disaggregation of Revenue [Line Items]
Revenue	277	188	535	378
Services
Disaggregation of Revenue [Line Items]
Revenue	3,757	3,559	7,484	7,088
Subscription
Disaggregation of Revenue [Line Items]
Revenue	7,862	6,390	15,706	12,851
Subscription Revenue, Product
Disaggregation of Revenue [Line Items]
Revenue	4,432	3,110	8,851	6,317
Subscription Revenue, Service
Disaggregation of Revenue [Line Items]
Revenue	$ 3,430	$ 3,280	$ 6,855	$ 6,534