Supplemental Equity and Comprehensive Income Information - AOCI rf (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
AOCI Attributable to 3M, Net of Tax Roll Forward
Stockholders' Equity Attributable to 3M, Beginning Balance			$ 10,063
Other comprehensive income (loss), before tax:
Stockholders' Equity Attributable to 3M, Ending Balance	$ 10,857		10,857
Cumulative Translation Adjustment
AOCI Attributable to 3M, Net of Tax Roll Forward
Stockholders' Equity Attributable to 3M, Beginning Balance	(2,340)	$ (2,034)	(1,899)	$ (2,098)
Other comprehensive income (loss), before tax:
Amounts before reclassifications	104	(40)	(335)	63
Amounts reclassified out		142		142
Total other comprehensive income (loss), before tax	104	102	(335)	205
Tax effect	2	20		(6)
Total other comprehensive income (loss), net of tax	106	122	(335)	199
Stockholders' Equity Attributable to 3M, Ending Balance	(2,234)	(1,912)	(2,234)	(1,912)
Cumulative Translation Adjustment | 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		(13)		(13)
Defined Pension and Postretirement Plans Adjustment
AOCI Attributable to 3M, Net of Tax Roll Forward
Stockholders' Equity Attributable to 3M, Beginning Balance	(6,090)	(5,565)	(6,209)	(4,832)
Other comprehensive income (loss), before tax:
Amounts before reclassifications	(80)	153	(80)	153
Amounts reclassified out	162	105	326	209
Total other comprehensive income (loss), before tax	82	258	246	362
Tax effect	(24)	(62)	(69)	(82)
Total other comprehensive income (loss), net of tax	58	196	177	280
Stockholders' Equity Attributable to 3M, Ending Balance	(6,032)	(5,369)	(6,032)	(5,369)
Defined Pension and Postretirement Plans Adjustment | 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		(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	16	47	(31)	64
Other comprehensive income (loss), before tax:
Amounts before reclassifications	(15)	(30)	62	(17)
Amounts reclassified out	(31)	(20)	(47)	(27)
Total other comprehensive income (loss), before tax	(46)	(50)	15	(44)
Tax effect	10	12	(4)	12
Total other comprehensive income (loss), net of tax	(36)	(38)	11	(32)
Stockholders' Equity Attributable to 3M, Ending Balance	(20)	9	(20)	9
Cash Flow Hedging Instruments, Unrealized Gain (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		(23)		(23)
Total Accumulated Other Comprehensive Income (Loss)
AOCI Attributable to 3M, Net of Tax Roll Forward
Stockholders' Equity Attributable to 3M, Beginning Balance	(8,414)	(7,552)	(8,139)	(6,866)
Other comprehensive income (loss), before tax:
Amounts before reclassifications	9	83	(353)	199
Amounts reclassified out	131	227	279	324
Total other comprehensive income (loss), before tax	140	310	(74)	523
Tax effect	(12)	(30)	(73)	(76)
Total other comprehensive income (loss), net of tax	128	280	(147)	447
Stockholders' Equity Attributable to 3M, Ending Balance	$ (8,286)	(7,272)	$ (8,286)	(7,272)
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)