Supplemental Equity and Comprehensive Income Information - AOCI rf (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
AOCI Attributable to 3M, Net of Tax Roll Forward
Stockholders' Equity Attributable to 3M, Beginning Balance			$ 9,796
Other comprehensive income (loss), before tax:
Stockholders' Equity Attributable to 3M, Ending Balance	$ 10,083		10,083
ASU 2016-02 Leases
AOCI Attributable to 3M, Net of Tax Roll Forward
Impact of ASUs	14		14
Other comprehensive income (loss), before tax:
Impact of ASUs	14		14
Cumulative Translation Adjustment
AOCI Attributable to 3M, Net of Tax Roll Forward
Stockholders' Equity Attributable to 3M, Beginning Balance	(2,034)	$ (1,470)	(2,098)	$ (1,638)
Other comprehensive income (loss), before tax:
Amounts before reclassifications	(40)	(411)	63	(282)
Amounts reclassified out	142		142
Total other comprehensive income (loss), before tax	102	(411)	205	(282)
Tax effect	20	(81)	(6)	(42)
Total other comprehensive income (loss), net of tax	122	(492)	199	(324)
Stockholders' Equity Attributable to 3M, Ending Balance	(1,912)	(1,962)	(1,912)	(1,962)
Cumulative Translation Adjustment | ASU 2016-02 Leases
AOCI Attributable to 3M, Net of Tax Roll Forward
Impact of ASUs	(13)		(13)
Other comprehensive income (loss), before tax:
Impact of ASUs	(13)		(13)
Defined Pension and Postretirement Plans Adjustment
AOCI Attributable to 3M, Net of Tax Roll Forward
Stockholders' Equity Attributable to 3M, Beginning Balance	(5,565)	(5,160)	(4,832)	(5,276)
Other comprehensive income (loss), before tax:
Amounts before reclassifications	153		153
Amounts reclassified out	105	151	209	302
Total other comprehensive income (loss), before tax	258	151	362	302
Tax effect	(62)	(37)	(82)	(72)
Total other comprehensive income (loss), net of tax	196	114	280	230
Stockholders' Equity Attributable to 3M, Ending Balance	(5,369)	(5,046)	(5,369)	(5,046)
Defined Pension and Postretirement Plans Adjustment | ASU 2016-02 Leases
AOCI Attributable to 3M, Net of Tax Roll Forward
Impact of ASUs	(817)		(817)
Other comprehensive income (loss), before tax:
Impact of ASUs	(817)		(817)
Cash Flow Hedging Instruments, Unrealized Gain (Loss)
AOCI Attributable to 3M, Net of Tax Roll Forward
Stockholders' Equity Attributable to 3M, Beginning Balance	47	(173)	64	(112)
Other comprehensive income (loss), before tax:
Amounts before reclassifications	(30)	182	(17)	100
Amounts reclassified out	(20)	28	(27)	62
Total other comprehensive income (loss), before tax	(50)	210	(44)	162
Tax effect	12	(48)	12	(61)
Total other comprehensive income (loss), net of tax	(38)	162	(32)	101
Stockholders' Equity Attributable to 3M, Ending Balance	9	(11)	9	(11)
Cash Flow Hedging Instruments, Unrealized Gain (Loss) | ASU 2016-02 Leases
AOCI Attributable to 3M, Net of Tax Roll Forward
Impact of ASUs	(23)		(23)
Other comprehensive income (loss), before tax:
Impact of ASUs	(23)		(23)
Total Accumulated Other Comprehensive Income (Loss)
AOCI Attributable to 3M, Net of Tax Roll Forward
Stockholders' Equity Attributable to 3M, Beginning Balance	(7,552)	(6,803)	(6,866)	(7,026)
Other comprehensive income (loss), before tax:
Amounts before reclassifications	83	(229)	199	(182)
Amounts reclassified out	227	179	324	364
Total other comprehensive income (loss), before tax	310	(50)	523	182
Tax effect	(30)	(166)	(76)	(175)
Total other comprehensive income (loss), net of tax	280	(216)	447	7
Stockholders' Equity Attributable to 3M, Ending Balance	(7,272)	$ (7,019)	(7,272)	$ (7,019)
Total Accumulated Other Comprehensive Income (Loss) | ASU 2018-02 Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income
AOCI Attributable to 3M, Net of Tax Roll Forward
Impact of ASUs	(853)		(853)
Other comprehensive income (loss), before tax:
Impact of ASUs	(853)		(853)
Total Accumulated Other Comprehensive Income (Loss) | ASU 2016-02 Leases
AOCI Attributable to 3M, Net of Tax Roll Forward
Impact of ASUs	(853)		(853)
Other comprehensive income (loss), before tax:
Impact of ASUs	$ (853)		$ (853)