Significant Accounting Policies (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Earnings per share
Options outstanding not included in computation of diluted earnings per share (in shares)	0	6.3	2.6	15.6
Numerator:
Net income attributable to 3M	$ 1,230	$ 1,161	$ 3,556	$ 3,453
Denominator:
Denominator for weighted average 3M common shares outstanding - basic (in shares)	679.8	693.0	686.4	694.7
Dilution associated with the Company's stock-based compensation plans (in shares)	12.0	10.1	11.3	9.2
Denominator for weighted average 3M common shares outstanding - diluted (in shares)	691.8	703.1	697.7	703.9
Earnings per share attributable to 3M common shareholders - basic (in dollars per share)	$ 1.81	$ 1.68	$ 5.18	$ 4.97
Earnings per share attributable to 3M common shareholders - diluted (in dollars per share)	$ 1.78	$ 1.65	$ 5.10	$ 4.91