Document and Entity Information - Jun. 30, 2015 - shares	Total
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	Jun. 30, 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	624,745,409
Document Fiscal Year Focus	2015
Document Fiscal Period Focus	Q2