Significant Accounting Policies (Details) In Millions, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended		12 Months Ended		3 Months Ended
	Sep. 30, 2014 USD ($)	Sep. 30, 2013 USD ($)	Sep. 30, 2014 USD ($)	Sep. 30, 2013 USD ($)	Dec. 31, 2013	Sep. 30, 2014 VEF	Jun. 30, 2014 Business Segments Electronics and Energy Divisions
Basis Of Presentation
Number of existing divisions prior to division combination							3
Number of divisions that exist after the division combination							2
Foreign Currency Translation
Threshold percentage used to determine if economic environment is highly inflationary			100.00%
Number of years used to determine if economic environment is highly inflationary			3 years
Operating income of Venezuelan subsidiary as percent of consolidated amount high end of range					1.00%
Cumulative inflation rate of Venezuela in November 2009 and since, low end of range			100.00%
Maximum balance of company's net monetary assets in Venezuelan bolivars						125
Exchange rate established by Venezuelan government from bolivars to dollars - SICAD1						10
Exchange rate established by Venezuelan government from bolivars to dollars - SICAD2						50
Earnings per share
Options outstanding not included in computation of diluted earnings per share (in shares)			1.8	2.6
Numerator:
Net income attributable to 3M	$ 1,303	$ 1,230	$ 3,777	$ 3,556
Denominator:
Denominator for weighted average 3M common shares outstanding - basic (in shares)	645.3	679.8	652.9	686.4
Dilution associated with the Company's stock-based compensation plans (in shares)	12.6	12.0	12.8	11.3
Denominator for weighted average 3M common shares outstanding - diluted (in shares)	657.9	691.8	665.7	697.7
Earnings per share attributable to 3M common shareholders - basic (in dollars per share)	$ 2.02	$ 1.81	$ 5.78	$ 5.18
Earnings per share attributable to 3M common shareholders - diluted (in dollars per share)	$ 1.98	$ 1.78	$ 5.67	$ 5.10