Significant Accounting Policies (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Earnings per share
Options outstanding not included in computation of diluted earnings per share (in shares)	4.1	19.2
Numerator:
Net income attributable to 3M	$ 1,129	$ 1,125
Denominator:
Denominator for weighted average 3M common shares outstanding - basic (in shares)	691.1	696.8
Dilution associated with the Company's stock-based compensation plans (in shares)	11.0	9.3
Denominator for weighted average 3M common shares outstanding - diluted (in shares)	702.1	706.1
Earnings per share attributable to 3M common shareholders - basic (in dollars per share)	$ 1.63	$ 1.61
Earnings per share attributable to 3M common shareholders - diluted (in dollars per share)	$ 1.61	$ 1.59