Supplemental Equity and Comprehensive Income Information (Details 6) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Amount Reclassified from Accumulated Other Comprehensive Income
Selling, general and administrative expenses	$ (1,610)	$ (1,528)	$ (3,199)	$ (3,080)
Total before tax	(110)	(136)	(253)	153
Tax effect	(458)	(509)	(928)	(971)
Net of tax	1,032	940	1,910	2,305
Reclassifications out of Accumulated Other Comprehensive Income Attributable to 3M
Amount Reclassified from Accumulated Other Comprehensive Income
Net of tax	(126)	(103)	(280)	(204)
Defined Benefit Pension and Postretirement Plans Adjustment
Amount Reclassified from Accumulated Other Comprehensive Income
Total before tax	144	154	287	307
Defined Benefit Pension and Postretirement Plans Adjustment | Reclassifications out of Accumulated Other Comprehensive Income Attributable to 3M
Amount Reclassified from Accumulated Other Comprehensive Income
Transition asset	0	0	1	1
Prior service benefit	20	22	40	42
Net actuarial loss	(164)	(176)	(328)	(350)
Total before tax	(144)	(154)	(287)	(307)
Tax effect	53	56	111	112
Net of tax	(91)	(98)	(176)	(195)
Debt and Equity Securities, Unrealized Gain (Loss)
Amount Reclassified from Accumulated Other Comprehensive Income
Total before tax	(6)	(3)	(6)	2
Debt and Equity Securities, Unrealized Gain (Loss) | Reclassifications out of Accumulated Other Comprehensive Income Attributable to 3M
Amount Reclassified from Accumulated Other Comprehensive Income
Selling, general and administrative expenses	0	0	0	(1)
Total before tax	0	0	0	(1)
Tax effect	0	0	0	0
Net of tax	0	0	0	(1)
Cash Flow Hedging Instruments Unrealized Gain (Loss)
Amount Reclassified from Accumulated Other Comprehensive Income
Total before tax	12	37	50	13
Cash Flow Hedging Instruments Unrealized Gain (Loss) | Reclassifications out of Accumulated Other Comprehensive Income Attributable to 3M
Amount Reclassified from Accumulated Other Comprehensive Income
Total before tax	(54)	(8)	(162)	(12)
Tax effect	19	3	58	4
Net of tax	(35)	(5)	(104)	(8)
Cash Flow Hedging Instruments Unrealized Gain (Loss) | Foreign currency forward/option contracts | Reclassifications out of Accumulated Other Comprehensive Income Attributable to 3M
Amount Reclassified from Accumulated Other Comprehensive Income
Cost of sales	(3)	9	(9)	9
Cash Flow Hedging Instruments Unrealized Gain (Loss) | Foreign currency forward contracts | Reclassifications out of Accumulated Other Comprehensive Income Attributable to 3M
Amount Reclassified from Accumulated Other Comprehensive Income
Interest expense	(52)	(13)	(153)	(13)
Cash Flow Hedging Instruments Unrealized Gain (Loss) | Commodity price swap contracts | Reclassifications out of Accumulated Other Comprehensive Income Attributable to 3M
Amount Reclassified from Accumulated Other Comprehensive Income
Cost of sales	$ 1	$ (4)	$ 0	$ (8)