Supplemental Equity and Comprehensive Income Information - AOCI rf (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
AOCI Attributable to 3M, Net of Tax Roll Forward
Stockholders' Equity Attributable to 3M, Beginning Balance			$ 11,563
Other comprehensive income (loss), before tax:
Stockholders' Equity Attributable to 3M, Ending Balance	$ 10,248		10,248
Accumulated Other Comprehensive Income (Loss)
AOCI Attributable to 3M, Net of Tax Roll Forward
Stockholders' Equity Attributable to 3M, Beginning Balance	(7,019)	$ (6,989)	(7,026)	$ (7,245)
Other comprehensive income (loss), before tax:
Amounts before reclassifications	(88)	(109)	(270)	(225)
Amounts reclassified out	187	121	551	336
Total other comprehensive income (loss), before tax	99	12	281	111
Tax effect	(48)	64	(223)	221
Total other comprehensive income (loss), net of tax	51	76	58	332
Stockholders' Equity Attributable to 3M, Ending Balance	(6,968)	(6,913)	(6,968)	(6,913)
Cumulative Translation Adjustment
AOCI Attributable to 3M, Net of Tax Roll Forward
Stockholders' Equity Attributable to 3M, Beginning Balance	(1,962)	(1,786)	(1,638)	(2,008)
Other comprehensive income (loss), before tax:
Amounts before reclassifications	(110)	(29)	(392)	30
Total other comprehensive income (loss), before tax	(110)	(29)	(392)	30
Tax effect	1	74	(41)	237
Total other comprehensive income (loss), net of tax	(109)	45	(433)	267
Stockholders' Equity Attributable to 3M, Ending Balance	(2,071)	(1,741)	(2,071)	(1,741)
Gains (losses) associated with defined benefit pension and postretirement plans amortization
AOCI Attributable to 3M, Net of Tax Roll Forward
Stockholders' Equity Attributable to 3M, Beginning Balance	(5,046)	(5,167)	(5,276)	(5,328)
Other comprehensive income (loss), before tax:
Amounts reclassified out	150	119	452	357
Total other comprehensive income (loss), before tax	150	119	452	357
Tax effect	(36)	(39)	(108)	(116)
Total other comprehensive income (loss), net of tax	114	80	344	241
Stockholders' Equity Attributable to 3M, Ending Balance	(4,932)	(5,087)	(4,932)	(5,087)
Cash flow hedging instruments gains (losses)
AOCI Attributable to 3M, Net of Tax Roll Forward
Stockholders' Equity Attributable to 3M, Beginning Balance	(11)	(36)	(112)	91
Other comprehensive income (loss), before tax:
Amounts before reclassifications	22	(80)	122	(255)
Amounts reclassified out	37	2	99	(21)
Total other comprehensive income (loss), before tax	59	(78)	221	(276)
Tax effect	(13)	29	(74)	100
Total other comprehensive income (loss), net of tax	46	(49)	147	(176)
Stockholders' Equity Attributable to 3M, Ending Balance	$ 35	$ (85)	$ 35	$ (85)