Document and Entity Information	3 Months Ended
	Mar. 31, 2015
Document and Entity Information [Abstract]
Entity Registrant Name	3M CO
Trading Symbol	MMM
Entity Central Index Key	0000066740
Document Type	10-Q
Document Period End Date	Mar. 31, 2015
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding	634,340,975
Document Fiscal Year Focus	2015
Document Fiscal Period Focus	Q1