Revenue - Disaggregation of Revenue (Details) - USD ($) $ in Millions	12 Months Ended
	Jul. 26, 2025	Jul. 27, 2024	Jul. 29, 2023
Disaggregation of Revenue [Line Items]
Total revenue	$ 56,654	$ 53,803	$ 56,998
Product
Disaggregation of Revenue [Line Items]
Total revenue	41,608	39,253	43,142
Networking
Disaggregation of Revenue [Line Items]
Total revenue	28,304	29,229	34,570
Security
Disaggregation of Revenue [Line Items]
Total revenue	8,094	5,075	3,859
Collaboration
Disaggregation of Revenue [Line Items]
Total revenue	4,154	4,113	4,052
Observability
Disaggregation of Revenue [Line Items]
Total revenue	1,055	837	661
Services
Disaggregation of Revenue [Line Items]
Total revenue	15,046	14,550	13,856
Subscription
Disaggregation of Revenue [Line Items]
Total revenue	31,526	27,380	24,640
Subscription, Product
Disaggregation of Revenue [Line Items]
Total revenue	17,783	14,078	11,931
Subscription, Service
Disaggregation of Revenue [Line Items]
Total revenue	$ 13,743	$ 13,302	$ 12,709