Cover Page - USD ($)	12 Months Ended
	Oct. 02, 2020	Nov. 13, 2020	Apr. 03, 2020
Cover [Abstract]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Oct. 02, 2020
Current Fiscal Year End Date	--10-02
Document Transition Report	false
Entity File Number	1-7598
Entity Registrant Name	VARIAN MEDICAL SYSTEMS, INC.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	94-2359345
Entity Address, Address Line One	3100 Hansen Way
Entity Address, City or Town	Palo Alto
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94304-1038
City Area Code	(650)
Local Phone Number	493-4000
Title of 12(b) Security	Common Stock, $1 par value
Trading Symbol	VAR
Security Exchange Name	NYSE
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Amendment Flag	false
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	FY
Entity Central Index Key	0000203527
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	true
Entity Shell Company	false
Entity Public Float			$ 6,905,810,423
Entity Common Stock, Shares Outstanding		91,355,469
Documents Incorporated by Reference	Definitive Proxy Statement for the Company’s 2021 Annual Meeting of Stockholders — Part III of this Form 10-K