Significant Accounting Policies - Foreign Currency Translation (Details) - Subsidiary $ in Millions, $ in Millions, in Billions	3 Months Ended			12 Months Ended
	Mar. 31, 2019 VEF ( )	Sep. 30, 2018 item	Jun. 30, 2018	Dec. 31, 2018	Mar. 31, 2019 ARS ($)	Mar. 31, 2019 USD ($)
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	3,333				3,333	3,333
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	43				43	43
Maximum | Venezuela
Foreign Currency Translation
Balance of the Company's overall net monetary assets valued functional currency |	60
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					$ 190