Document and Entity Information	9 Months Ended
	Sep. 30, 2017 shares
Document and Entity Information [Abstract]
Entity Registrant Name	Thermo Fisher Scientific Inc.
Entity Central Index Key	0000097745
Document Type	10-Q
Document Period End Date	Sep. 30, 2017
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2017
Document Fiscal Period Focus	Q3
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding	400,995,357
Entity Stock Trading Symbol	TMO