Document and Entity Information - USD ($) shares in Millions, $ in Billions	12 Months Ended
	Dec. 31, 2017	Jan. 31, 2018	Jun. 30, 2017
Document and Entity Information
Entity Registrant Name	3M Company
Trading Symbol	mmm
Entity Central Index Key	0000066740
Document Type	10-K
Document Period End Date	Dec. 31, 2017
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Well Known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Public Float		$ 149.2	$ 124.2
Entity Common Stock, Shares Outstanding		595.5
Document Fiscal Year Focus	2017
Document Fiscal Period Focus	FY