Revenue - Disaggregation of Revenue (Details) - USD ($) $ in Millions	3 Months Ended
	Oct. 26, 2024	Oct. 28, 2023
Disaggregation of Revenue [Line Items]
Revenue	$ 13,841	$ 14,668
Product
Disaggregation of Revenue [Line Items]
Revenue	10,114	11,139
Networking
Disaggregation of Revenue [Line Items]
Revenue	6,753	8,822
Security
Disaggregation of Revenue [Line Items]
Revenue	2,017	1,010
Collaboration
Disaggregation of Revenue [Line Items]
Revenue	1,085	1,117
Observability
Disaggregation of Revenue [Line Items]
Revenue	258	190
Services
Disaggregation of Revenue [Line Items]
Revenue	3,727	3,529
Subscription
Disaggregation of Revenue [Line Items]
Revenue	7,844	6,461
Subscription Revenue, Product
Disaggregation of Revenue [Line Items]
Revenue	4,419	3,207
Subscription Revenue, Service
Disaggregation of Revenue [Line Items]
Revenue	$ 3,425	$ 3,254