Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130543-203045

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130539-203045

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130545-203045

Name:	us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Revenue (Disaggregation of Revenue) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jan. 26, 2019	Jan. 27, 2018	Jan. 26, 2019	Jan. 27, 2018
Disaggregation of Revenue [Line Items]
Revenue	$ 12,446	$ 11,887	$ 25,518	$ 24,023
Product
Disaggregation of Revenue [Line Items]
Revenue	9,273	8,709	19,163	17,763
Infrastructure Platforms
Disaggregation of Revenue [Line Items]
Revenue	7,128	6,710	14,770	13,690
Applications
Disaggregation of Revenue [Line Items]
Revenue	1,465	1,184	2,884	2,387
Security
Disaggregation of Revenue [Line Items]
Revenue	658	557	1,308	1,142
Other Products
Disaggregation of Revenue [Line Items]
Revenue	22	258	200	544
Other Products \| Discontinued operations, held-for-sale \| Service Provider Video
Disaggregation of Revenue [Line Items]
Revenue	0	230	168	478
Service
Disaggregation of Revenue [Line Items]
Revenue	$ 3,173	$ 3,178	$ 6,355	$ 6,260