Supplemental Equity and Comprehensive Income Information - Impact of NCI (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Supplemental Equity and Comprehensive Income Information
Net income attributable to 3M	$ 1,296	$ 1,303	$ 3,795	$ 3,777
Impact of purchase of subsidiary shares		(408)		(409)
Change in 3M Company shareholder's equity from net income attributable to 3M and impact of purchase of subsidiary shares		$ 895		$ 3,368