Commitments and Contingencies (Additional Information) (Details) $ in Millions									3 Months Ended		12 Months Ended
	Aug. 20, 2018 USD ($)	May 30, 2017 USD ($)	May 25, 2017 USD ($)	Mar. 14, 2017 USD ($)	Mar. 03, 2017 USD ($) patent	May 12, 2016 USD ($)	Jan. 15, 2016 patent claim	Sep. 04, 2013 patent	Oct. 27, 2018 USD ($)	Jan. 28, 2017 USD ($)	Jul. 28, 2018 USD ($)	Jul. 29, 2017 USD ($)	Jul. 30, 2016 USD ($)	Jul. 25, 2015 USD ($)	Jul. 26, 2014 USD ($)	Jul. 28, 2012 USD ($)
Site Contingency [Line Items]
Rent expense											$ 442.0	$ 403.0	$ 385.0
Liability for purchase commitments											159.0	162.0
Future compensation expense & contingent consideration (maximum)											352.0
Commitments and contingencies
Volume of channel partner financing											28,200.0	27,000.0	26,900.0
Balance of the channel partner financing subject to guarantees											953.0	1,000.0
Financing provided by third parties for leases and loans related to End Users on which the Company has provided guarantees											35.0	51.0	63.0
Total cost of sales											18,724.0	17,781.0	18,287.0
Brazilian authority claim of import tax evasion by importer tax portion											218.0
Brazilian authority claim of import tax evasion by importer interest portion											1,400.0
Brazilian authority claim of import tax evasion by importer penalties portion											1,000.0
SRI International
Site Contingency [Line Items]
Damages awarded, value						$ 23.7
Arista Networks, Inc Vs. Company | Subsequent Event
Site Contingency [Line Items]
Proceeds from Legal Settlements	$ 400.0
Arista Networks, Inc Vs. Company | Forecast
Site Contingency [Line Items]
Claims for patent infringement resolved by arbitration process, period									3 years
No actions brought for patent or copyright infringement for products currently on the market, period									5 years
Arista Networks, Inc Vs. Company | Arista Networks, Inc. | Forecast
Site Contingency [Line Items]
Payments for Legal Settlements									$ 400.0
Pending Litigation | SRI International
Site Contingency [Line Items]
Damages awarded, value			$ 57.0
Number of allegedly infringed patents (patent) | patent								2
Percentage of royalty awarded			3.50%
Damages from Product Defects
Site Contingency [Line Items]
Charge for expected remediation										$ 125.0
Patent Infringement | Pending Litigation | Sprint Communications Company L.P. Vs. Time Warner Cable Inc.
Site Contingency [Line Items]
Number of patents found infringed (patent) | patent					5
Damages awarded, value				$ 139.8	$ 139.8
Percentage of post-judgment interest awarded				1.06%
Pre-judgment interest requested		$ 20.3
Patent Infringement | Pending Litigation | Huawei Technologies Co. Ltd. Vs. T-Mobile US, Inc.
Site Contingency [Line Items]
Number of patent infringement actions filed (claim) | claim							4
Number of allegedly infringed patents (patent) | patent							12
Patent Indemnification
Site Contingency [Line Items]
Legal and indemnification settlement											127.0
Product
Site Contingency [Line Items]
Total cost of sales											$ 14,427.0	13,699.0	14,161.0
Minimum
Site Contingency [Line Items]
Warranty period for products, in days											90 days
Channel partners revolving short-term financing payment term											60 days
Maximum
Site Contingency [Line Items]
Warranty period for products, in years											5 years
Channel partners revolving short-term financing payment term											90 days
End user lease and loan term											3 years
Insieme Networks Inc
Site Contingency [Line Items]
Initial funding																$ 100.0
Payments to acquire additional interest in subsidiaries												441.0
Compensation expense												47.0	160.0
Investments in privately held companies (impaired)
Site Contingency [Line Items]
Commitments and contingencies											$ 223.0	216.0
Supplier Component Remediation Liability
Site Contingency [Line Items]
Loss contingency accrual											44.0	174.0
Supplier Component Remediation Liability | Cost of Goods, Product Line
Site Contingency [Line Items]
Adjustments to product cost of sales											$ 58.0	$ 141.0	$ 74.0	$ 164.0
Supplier Component Remediation Liability | Product
Site Contingency [Line Items]
Total cost of sales															$ 655.0