Supplemental Equity and Comprehensive Income Information (Details 3) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Amount Reclassified from Accumulated Other Comprehensive Income
Selling, general and administrative expenses	$ (1,597)	$ (1,609)	$ (4,875)	$ (4,808)
Total before tax	(342)	349	(35)	96
Tax effect	(569)	(471)	(1,569)	(1,399)
Net of tax	836	1,586	3,557	3,496
Reclassifications out of Accumulated Other Comprehensive Income Attributable to 3M
Amount Reclassified from Accumulated Other Comprehensive Income
Net of tax	(65)	(64)	(185)	(345)
Defined Benefit Pension and Postretirement Plans Adjustment
Amount Reclassified from Accumulated Other Comprehensive Income
Total before tax	89	144	272	431
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	1	0	1	1
Prior service benefit	15	19	45	59
Net actuarial loss	(105)	(163)	(318)	(491)
Total before tax	(89)	(144)	(272)	(431)
Tax effect	30	52	92	163
Net of tax	(59)	(92)	(180)	(268)
Debt and Equity Securities, Unrealized Gain (Loss)
Amount Reclassified from Accumulated Other Comprehensive Income
Total before tax	(1)	3	2	(3)
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	0
Total before tax	0	0	0	0
Tax effect	0	0	0	0
Net of tax	0	0	0	0
Cash Flow Hedging Instruments Unrealized Gain (Loss)
Amount Reclassified from Accumulated Other Comprehensive Income
Total before tax	107	(38)	94	12
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	(9)	43	(8)	(121)
Tax effect	3	(15)	3	44
Net of tax	(6)	28	(5)	(77)
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	(7)	1	(9)	(8)
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	0	44	0	(111)
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)	(1)	2	(1)
Cash Flow Hedging Instruments Unrealized Gain (Loss) | Interest rate swap contracts | Reclassifications out of Accumulated Other Comprehensive Income Attributable to 3M
Amount Reclassified from Accumulated Other Comprehensive Income
Interest expense	$ (1)	$ (1)	$ (1)	$ (1)