Revenue - Disaggregation of Revenue (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jan. 24, 2026	Jan. 25, 2025	Jan. 24, 2026	Jan. 25, 2025
Disaggregation of Revenue [Line Items]
Revenue	$ 15,349	$ 13,991	$ 30,232	$ 27,832
Product
Disaggregation of Revenue [Line Items]
Revenue	11,642	10,234	22,719	20,348
Networking
Disaggregation of Revenue [Line Items]
Revenue	8,294	6,850	16,061	13,603
Security
Disaggregation of Revenue [Line Items]
Revenue	2,018	2,111	3,998	4,129
Collaboration
Disaggregation of Revenue [Line Items]
Revenue	1,054	996	2,109	2,081
Observability
Disaggregation of Revenue [Line Items]
Revenue	277	277	550	535
Services
Disaggregation of Revenue [Line Items]
Revenue	3,707	3,757	7,513	7,484
Subscription
Disaggregation of Revenue [Line Items]
Revenue	7,836	7,862	15,836	15,706
Subscription Revenue, Product
Disaggregation of Revenue [Line Items]
Revenue	4,474	4,432	8,974	8,851
Subscription Revenue, Service
Disaggregation of Revenue [Line Items]
Revenue	$ 3,362	$ 3,430	$ 6,862	$ 6,855