Revenue - Disaggregation of Revenue (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Apr. 26, 2025	Apr. 27, 2024	Apr. 26, 2025	Apr. 27, 2024
Disaggregation of Revenue [Line Items]
Revenue	$ 14,149	$ 12,702	$ 41,981	$ 40,161
Product
Disaggregation of Revenue [Line Items]
Revenue	10,374	9,024	30,722	29,395
Networking
Disaggregation of Revenue [Line Items]
Revenue	7,068	6,522	20,671	22,425
Security
Disaggregation of Revenue [Line Items]
Revenue	2,013	1,304	6,142	3,288
Collaboration
Disaggregation of Revenue [Line Items]
Revenue	1,031	987	3,112	3,093
Observability
Disaggregation of Revenue [Line Items]
Revenue	261	211	796	589
Services
Disaggregation of Revenue [Line Items]
Revenue	3,775	3,678	11,259	10,766
Subscription
Disaggregation of Revenue [Line Items]
Revenue	7,916	6,854	23,622	19,705
Subscription Revenue, Product
Disaggregation of Revenue [Line Items]
Revenue	4,483	3,510	13,334	9,827
Subscription Revenue, Service
Disaggregation of Revenue [Line Items]
Revenue	$ 3,433	$ 3,344	$ 10,288	$ 9,878