Cover Page - shares	9 Months Ended
	Sep. 30, 2020	Oct. 27, 2020
Cover [Abstract]
Amendment Flag	false
Document Type	10-Q
Document Quarterly Report	true
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q3
Document Transition Report	false
Current Fiscal Year End Date	--12-31
Document Period End Date	Sep. 30, 2020
Entity Interactive Data Current	Yes
Entity Current Reporting Status	Yes
Entity Registrant Name	MKS INSTRUMENTS, INC.
Entity Central Index Key	0001049502
Trading Symbol	MKSI
Entity Filer Category	Large Accelerated Filer
Entity Shell Company	false
Entity Emerging Growth Company	false
Entity Small Business	false
Entity Common Stock, Shares Outstanding		55,137,088
Entity File Number	0-23621
Entity Tax Identification Number	04-2277512
Entity Address, Address Line One	2 Tech Drive, Suite 201,
Entity Address, City or Town	Andover
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	01810
Entity Incorporation, State or Country Code	MA
City Area Code	978
Local Phone Number	645-5500
Security Exchange Name	NASDAQ
Title of 12(b) Security	Common Stock