Significant Accounting Policies (Details) $ / shares in Units, shares in Millions, VEF in Millions, $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2016 USD ($) $ / shares shares	Mar. 31, 2015 USD ($) $ / shares shares	Dec. 31, 2015	Mar. 31, 2016 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%
Maximum balance of company's net monetary assets in Venezuelan bolivars | VEF				VEF 500
Exchange rate established by Venezuelan government from bolivars to dollars - DIPRO				10
Exchange rate established by Venezuelan government from bolivars to dollars - DICOM				260
Earnings per share
Options outstanding not included in computation of diluted earnings per share (in shares)	9.0	3.5
Numerator:
Net income attributable to 3M | $	$ 1,275	$ 1,199
Denominator:
Denominator for weighted average 3M common shares outstanding - basic (in shares)	607.4	636.2
Dilution associated with the Company's stock-based compensation plans (in shares)	13.9	13.0
Denominator for weighted average 3M common shares outstanding - diluted (in shares)	621.3	649.2
Earnings per share attributable to 3M common shareholders - basic (in dollars per share) | $ / shares	$ 2.10	$ 1.88
Earnings per share attributable to 3M common shareholders - diluted (in dollars per share) | $ / shares	$ 2.05	$ 1.85