Supplemental Equity and Comprehensive Income Information - AOCI rf (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 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	$ 10,365		10,365
Accumulated Other Comprehensive Income (Loss)
AOCI Attributable to 3M, Net of Tax Roll Forward
Stockholders' Equity Attributable to 3M, Beginning Balance	(6,803)	$ (6,949)	(7,026)	$ (7,245)
Other comprehensive income (loss), before tax:
Amounts before reclassifications	(229)	(241)	(182)	(116)
Amounts reclassified out	179	114	364	215
Total other comprehensive income (loss), before tax	(50)	(127)	182	99
Tax effect	(166)	87	(175)	157
Total other comprehensive income (loss), net of tax	(216)	(40)	7	256
Stockholders' Equity Attributable to 3M, Ending Balance	(7,019)	(6,989)	(7,019)	(6,989)
Cumulative Translation Adjustment
AOCI Attributable to 3M, Net of Tax Roll Forward
Stockholders' Equity Attributable to 3M, Beginning Balance	(1,470)	(1,719)	(1,638)	(2,008)
Other comprehensive income (loss), before tax:
Amounts before reclassifications	(411)	(167)	(282)	59
Total other comprehensive income (loss), before tax	(411)	(167)	(282)	59
Tax effect	(81)	100	(42)	163
Total other comprehensive income (loss), net of tax	(492)	(67)	(324)	222
Stockholders' Equity Attributable to 3M, Ending Balance	(1,962)	(1,786)	(1,962)	(1,786)
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	(5,160)	(5,245)	(5,276)	(5,328)
Other comprehensive income (loss), before tax:
Amounts reclassified out	151	119	302	238
Total other comprehensive income (loss), before tax	151	119	302	238
Tax effect	(37)	(41)	(72)	(77)
Total other comprehensive income (loss), net of tax	114	78	230	161
Stockholders' Equity Attributable to 3M, Ending Balance	(5,046)	(5,167)	(5,046)	(5,167)
Cash flow hedging instruments gains (losses)
AOCI Attributable to 3M, Net of Tax Roll Forward
Stockholders' Equity Attributable to 3M, Beginning Balance	(173)	15	(112)	91
Other comprehensive income (loss), before tax:
Amounts before reclassifications	182	(74)	100	(175)
Amounts reclassified out	28	(5)	62	(23)
Total other comprehensive income (loss), before tax	210	(79)	162	(198)
Tax effect	(48)	28	(61)	71
Total other comprehensive income (loss), net of tax	162	(51)	101	(127)
Stockholders' Equity Attributable to 3M, Ending Balance	$ (11)	$ (36)	$ (11)	$ (36)