Significant Accounting Policies (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Earnings per share
Options outstanding not included in computation of diluted earnings per share (in shares)	3.7	21.3	3.9	20.3
Numerator:
Net income attributable to 3M	$ 1,197	$ 1,167	$ 2,326	$ 2,292
Denominator:
Denominator for weighted average 3M common shares outstanding - basic (in shares)	688.2	694.3	689.6	695.5
Dilution associated with the Company's stock-based compensation plans (in shares)	10.9	8.3	11.0	8.9
Denominator for weighted average 3M common shares outstanding - diluted (in shares)	699.1	702.6	700.6	704.4
Earnings per share attributable to 3M common shareholders - basic (in dollars per share)	$ 1.74	$ 1.68	$ 3.37	$ 3.30
Earnings per share attributable to 3M common shareholders - diluted (in dollars per share)	$ 1.71	$ 1.66	$ 3.32	$ 3.25