Supplemental Equity and Comprehensive Income Information - AOCI Rollforward (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
AOCI Attributable to 3M, Net of Tax Roll Forward
Balance at the beginning of the period	$ 14,516	$ 10,925	$ 12,931	$ 10,126
Other comprehensive income (loss), before tax:
Total other comprehensive income (loss), net of tax	(135)	316	100	144
Balance at the end of the period	14,530	11,959	14,530	11,959
Total Accumulated Other Comprehensive Income (Loss)
AOCI Attributable to 3M, Net of Tax Roll Forward
Balance at the beginning of the period	(7,486)	(8,303)	(7,721)	(8,134)
Other comprehensive income (loss), before tax:
Amounts before reclassifications	(242)	165	(219)	(188)
Amounts reclassified out	176	128	516	378
Total other comprehensive income (loss), before tax	(66)	293	297	190
Tax effect	(68)	22	(196)	(44)
Total other comprehensive income (loss), net of tax	(134)	315	101	146
Balance at the end of the period	(7,620)	(7,988)	(7,620)	(7,988)
Cumulative Translation Adjustment
AOCI Attributable to 3M, Net of Tax Roll Forward
Balance at the beginning of the period	(1,502)	(2,234)	(1,450)	(1,899)
Other comprehensive income (loss), before tax:
Amounts before reclassifications	(286)	237	(303)	(98)
Total other comprehensive income (loss), before tax	(286)	237	(303)	(98)
Tax effect	(15)	33	(50)	33
Total other comprehensive income (loss), net of tax	(301)	270	(353)	(65)
Balance at the end of the period	(1,803)	(1,964)	(1,803)	(1,964)
Defined Benefit Pension and Postretirement Plans Adjustment
AOCI Attributable to 3M, Net of Tax Roll Forward
Balance at the beginning of the period	(5,858)	(6,049)	(6,098)	(6,204)
Other comprehensive income (loss), before tax:
Amounts before reclassifications				(80)
Amounts reclassified out	158	149	477	446
Total other comprehensive income (loss), before tax	158	149	477	366
Tax effect	(39)	(33)	(118)	(95)
Total other comprehensive income (loss), net of tax	119	116	359	271
Balance at the end of the period	(5,739)	(5,933)	(5,739)	(5,933)
Cash Flow Hedging Instruments, Unrealized Gain (Loss)
AOCI Attributable to 3M, Net of Tax Roll Forward
Balance at the beginning of the period	(126)	(20)	(173)	(31)
Other comprehensive income (loss), before tax:
Amounts before reclassifications	44	(72)	84	(10)
Amounts reclassified out	18	(21)	39	(68)
Total other comprehensive income (loss), before tax	62	(93)	123	(78)
Tax effect	(14)	22	(28)	18
Total other comprehensive income (loss), net of tax	48	(71)	95	(60)
Balance at the end of the period	$ (78)	$ (91)	$ (78)	$ (91)