Supplemental Equity and Comprehensive Income Information - AOCI rf (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Jun. 30, 2020	Dec. 31, 2019	Jun. 30, 2019	Dec. 31, 2018
AOCI Attributable to 3M, Net of Tax Roll Forward
Stockholders' Equity Attributable to 3M, Beginning Balance			$ 10,063
Impact of ASUs	$ 11,943	$ 10,764	11,943	$ 10,764	$ 10,915	$ 10,126	$ 10,142	$ 9,848
Other comprehensive income (loss), before tax:
Stockholders' Equity Attributable to 3M, Ending Balance	11,880		11,880
Cumulative Translation Adjustment
AOCI Attributable to 3M, Net of Tax Roll Forward
Stockholders' Equity Attributable to 3M, Beginning Balance	(2,234)	(1,912)	(1,899)	(2,098)
Other comprehensive income (loss), before tax:
Amounts before reclassifications	237	(149)	(98)	(86)
Amounts reclassified out				142
Total other comprehensive income (loss), before tax	237	(149)	(98)	56
Tax effect	33	(51)	33	(57)
Total other comprehensive income (loss), net of tax	270	(200)	(65)	(1)
Stockholders' Equity Attributable to 3M, Ending Balance	(1,964)	(2,112)	(1,964)	(2,112)
Cumulative Translation Adjustment | ASU 2018-02 Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income | Cumulative Effect, Period of Adoption, Adjustment
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	(6,032)	(5,369)	(6,209)	(4,832)
Other comprehensive income (loss), before tax:
Amounts before reclassifications			(80)	153
Amounts reclassified out	163	101	489	310
Total other comprehensive income (loss), before tax	163	101	409	463
Tax effect	(36)	(25)	(105)	(107)
Total other comprehensive income (loss), net of tax	127	76	304	356
Stockholders' Equity Attributable to 3M, Ending Balance	(5,905)	(5,293)	(5,905)	(5,293)
Defined Pension and Postretirement Plans Adjustment | ASU 2018-02 Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income | Cumulative Effect, Period of Adoption, Adjustment
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	(20)	9	(31)	64
Other comprehensive income (loss), before tax:
Amounts before reclassifications	(72)	31	(10)	14
Amounts reclassified out	(21)	(21)	(68)	(48)
Total other comprehensive income (loss), before tax	(93)	10	(78)	(34)
Tax effect	22	(2)	18	10
Total other comprehensive income (loss), net of tax	(71)	8	(60)	(24)
Stockholders' Equity Attributable to 3M, Ending Balance	(91)	17	(91)	17
Cash Flow Hedging Instruments, Unrealized Gain (Loss) | ASU 2018-02 Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income | Cumulative Effect, Period of Adoption, Adjustment
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	(8,286)	(7,272)	(8,139)	(6,866)
Impact of ASUs	(7,960)	(7,388)	(7,960)	(7,388)	$ (8,286)	$ (8,139)	$ (7,272)	(6,866)
Other comprehensive income (loss), before tax:
Amounts before reclassifications	165	(118)	(188)	81
Amounts reclassified out	142	80	421	404
Total other comprehensive income (loss), before tax	307	(38)	233	485
Tax effect	19	(78)	(54)	(154)
Total other comprehensive income (loss), net of tax	326	(116)	179	331
Stockholders' Equity Attributable to 3M, Ending Balance	$ (7,960)	(7,388)	$ (7,960)	(7,388)
Total Accumulated Other Comprehensive Income (Loss) | ASU 2018-02 Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income | Cumulative Effect, Period of Adoption, Adjustment
AOCI Attributable to 3M, Net of Tax Roll Forward
Impact of ASUs		$ (853)		$ (853)				$ (853)