Significant Accounting Policies (Details) In Millions, except Per Share data, unless otherwise specified	3 Months Ended		12 Months Ended
	Mar. 31, 2015 USD ($)	Mar. 31, 2014 USD ($)	Dec. 31, 2014	Mar. 31, 2015 VEF
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				100
Maximum balance of intercompany receivables due to 3M Company from its Venezuelan subsidiary	20
Exchange rate established by Venezuelan government from bolivars to dollars - CENCOEX	6
Exchange rate established by Venezuelan government from bolivars to dollars - SICAD	12
Exchange rate established by Venezuelan government from bolivars to dollars - SIMADI	190
Earnings per share
Options outstanding not included in computation of diluted earnings per share (in shares)	3.5	2.3
Numerator:
Net income attributable to 3M	$ 1,199	$ 1,207
Denominator:
Denominator for weighted average 3M common shares outstanding - basic (in shares)	636.2	661.5
Dilution associated with the Company's stock-based compensation plans (in shares)	13.0	13.0
Denominator for weighted average 3M common shares outstanding - diluted (in shares)	649.2	674.5
Earnings per share attributable to 3M common shareholders - basic (in dollars per share)	$ 1.88	$ 1.83
Earnings per share attributable to 3M common shareholders - diluted (in dollars per share)	$ 1.85	$ 1.79