Document and Entity Information - shares	6 Months Ended
	Jun. 29, 2019	Jul. 22, 2019
Cover page.
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Jun. 29, 2019
Document Transition Report	false
Entity File Number	001-32598
Entity Incorporation, State or Country Code	DE
Entity Address, Address Line One	129 Concord Road,
Entity Address, City or Town	Billerica,
Entity Address, State or Province	MA
Entity Tax Identification Number	41-1941551
Entity Address, Postal Zip Code	01821
City Area Code	978
Local Phone Number	436-6500
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Title of 12(b) Security	Common stock, $0.01 par value per share
Trading Symbol	ENTG
Security Exchange Name	NASDAQ
Entity Common Stock, Shares Outstanding		135,173,392
Amendment Flag	false
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q2
Entity Registrant Name	ENTEGRIS INC
Entity Central Index Key	0001101302
Current Fiscal Year End Date	--12-31