Quarterly Data (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Quarterly Data (Unaudited)
Net Sales	$ 8,111	$ 7,991	$ 8,171	$ 7,863	$ 7,945	$ 8,152	$ 8,390	$ 8,278	$ 32,136	$ 32,765
Cost of sales	4,325	4,188	4,313	4,310	4,060	4,159	4,227	4,236	17,136	16,682	$ 16,055
Net income including noncontrolling interest	970	1,588	1,131	893	1,349	1,546	1,862	606	4,582	5,363	4,869
Net income attributable to 3M	$ 969	$ 1,583	$ 1,127	$ 891	$ 1,347	$ 1,543	$ 1,857	$ 602	$ 4,570	$ 5,349	$ 4,858
Earnings per share attributable to 3M common shareholders - basic (in dollars per share)	$ 1.68	$ 2.75	$ 1.95	$ 1.54	$ 2.32	$ 2.64	$ 3.14	$ 1.01	$ 7.92	$ 9.09	$ 8.13
Earnings per share attributable to 3M common shareholders - diluted (in dollars per share)	$ 1.66	$ 2.72	$ 1.92	$ 1.51	$ 2.27	$ 2.58	$ 3.07	$ 0.98	$ 7.81	$ 8.89	$ 7.93