Significant Accounting Policies - Foreign Currency Translation (Details) - Subsidiary $ in Millions, $ in Millions, in Billions	3 Months Ended	9 Months Ended	12 Months Ended
	Sep. 30, 2018 VEF ( ) item	Sep. 30, 2018 VEF ( )	Dec. 31, 2017	Sep. 30, 2018 ARS ($)	Sep. 30, 2018 USD ($)
Venezuela
Foreign Currency Translation
Accumulated other comprehensive loss that 3M Company has recorded from its Venezuelan subsidiary					$ 145
Denominator used to determine conversion from Venezuelan Bolivar to Sovereign Bolivar. | item	100,000
Foreign currency exchange rate	62	62		62	62
Argentina
Foreign Currency Translation
Threshold percentage used to determine if economic environment is highly inflationary		100.00%
Number of years used to determine if economic environment is highly inflationary		3 years
Foreign currency exchange rate	41	41		41	41
Maximum | Venezuela
Foreign Currency Translation
Balance of the Company's overall net monetary assets valued functional currency |	2	2
Maximum | Argentina
Foreign Currency Translation
Operating income of subsidiaries as percent of consolidated amount high end of range			0.50%
Balance of the Company's overall net monetary assets valued functional currency				$ 300