Revenue - Disaggregation of Revenue (Details) - USD ($) $ in Millions	12 Months Ended
	Jul. 27, 2024	Jul. 29, 2023	Jul. 30, 2022
Disaggregation of Revenue [Line Items]
Total revenue	$ 53,803	$ 56,998	$ 51,557
Product
Disaggregation of Revenue [Line Items]
Total revenue	39,253	43,142	38,018
Networking
Disaggregation of Revenue [Line Items]
Total revenue	29,229	34,570	29,265
Security
Disaggregation of Revenue [Line Items]
Total revenue	5,075	3,859	3,699
Collaboration
Disaggregation of Revenue [Line Items]
Total revenue	4,113	4,052	4,472
Observability
Disaggregation of Revenue [Line Items]
Total revenue	837	661	581
Services
Disaggregation of Revenue [Line Items]
Total revenue	14,550	13,856	13,539
Subscription
Disaggregation of Revenue [Line Items]
Total revenue	27,380	24,640	22,393
Subscription, Product
Disaggregation of Revenue [Line Items]
Total revenue	14,078	11,931	10,030
Subscription, Service
Disaggregation of Revenue [Line Items]
Total revenue	$ 13,302	$ 12,709	$ 12,363