Significant Accounting Policies (Details) In Millions, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2014 USD ($)	Jun. 30, 2013 USD ($)	Jun. 30, 2014 USD ($)	Jun. 30, 2013 USD ($)	Dec. 31, 2013	Jun. 30, 2014 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 liabilities in Venezuelan bolivars						115
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)	3.1	3.7	2.7	3.9
Numerator:
Net income attributable to 3M	$ 1,267	$ 1,197	$ 2,474	$ 2,326
Denominator:
Denominator for weighted average 3M common shares outstanding - basic (in shares)	652.0	688.2	656.7	689.6
Dilution associated with the Company's stock-based compensation plans (in shares)	12.6	10.9	12.9	11.0
Denominator for weighted average 3M common shares outstanding - diluted (in shares)	664.6	699.1	669.6	700.6
Earnings per share attributable to 3M common shareholders - basic (in dollars per share)	$ 1.94	$ 1.74	$ 3.77	$ 3.37
Earnings per share attributable to 3M common shareholders - diluted (in dollars per share)	$ 1.91	$ 1.71	$ 3.70	$ 3.32