Quarterly Data (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Quarterly Data (Unaudited)
Net Sales	$ 8,583	$ 8,350	$ 7,176	$ 8,075	$ 8,111	$ 7,991	$ 8,171	$ 7,863	$ 32,184	$ 32,136	$ 32,765
Cost of sales	4,388	4,303	3,805	4,109	4,325	4,188	4,313	4,310	16,605	17,136	16,682
Net income including noncontrolling interest	1,390	1,417	1,287	1,294	970	1,588	1,131	893	5,388	4,582	5,363
Net income attributable to 3M	$ 1,389	$ 1,413	$ 1,290	$ 1,292	$ 969	$ 1,583	$ 1,127	$ 891	$ 5,384	$ 4,570	$ 5,349
Earnings per share attributable to 3M common shareholders - basic (in dollars per share)	$ 2.40	$ 2.45	$ 2.24	$ 2.24	$ 1.68	$ 2.75	$ 1.95	$ 1.54	$ 9.32	$ 7.92	$ 9.09
Earnings per share attributable to 3M common shareholders - diluted (in dollars per share)	$ 2.38	$ 2.43	$ 2.22	$ 2.22	$ 1.66	$ 2.72	$ 1.92	$ 1.51	$ 9.25	$ 7.81	$ 8.89