Supplemental Equity and Comprehensive Income Information (Details 3) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Amount Reclassified from Accumulated Other Comprehensive Income
Selling, general and administrative expenses	$ (1,550)	$ (1,646)	$ (3,114)	$ (3,278)
Total before tax	79	205	292	307
Tax effect	(509)	(537)	(1,011)	(1,000)
Net of tax	1,388	1,442	2,555	2,721
Reclassifications out of Accumulated Other Comprehensive Income Attributable to 3M
Amount Reclassified from Accumulated Other Comprehensive Income
Net of tax	(74)	(63)	(135)	(120)
Gains (losses) associated with defined benefit pension and postretirement plans amortization
Amount Reclassified from Accumulated Other Comprehensive Income
Total before tax	141	92	289	183
Gains (losses) associated with defined benefit pension and postretirement plans amortization | Reclassifications out of Accumulated Other Comprehensive Income Attributable to 3M
Amount Reclassified from Accumulated Other Comprehensive Income
Transition asset	1	0	1	0
Prior service benefit	17	15	35	30
Net actuarial loss	(159)	(107)	(318)	(213)
Curtailments/Settlements	0	0	17	0
Total before tax	(141)	(92)	(265)	(183)
Tax effect	45	32	91	62
Net of tax	(96)	(60)	(174)	(121)
Debt and equity security gains (losses)
Amount Reclassified from Accumulated Other Comprehensive Income
Total before tax	0	1	0	3
Debt and equity security gains (losses) | 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 gains (losses)
Amount Reclassified from Accumulated Other Comprehensive Income
Total before tax	(50)	(16)	59	(13)
Cash flow hedging instruments gains (losses) | Reclassifications out of Accumulated Other Comprehensive Income Attributable to 3M
Amount Reclassified from Accumulated Other Comprehensive Income
Total before tax	34	(5)	61	1
Tax effect	(12)	2	(22)	0
Net of tax	22	(3)	39	1
Cash flow hedging instruments gains (losses) | 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	35	(6)	65	(2)
Cash flow hedging instruments gains (losses) | Commodity price swap contracts | Reclassifications out of Accumulated Other Comprehensive Income Attributable to 3M
Amount Reclassified from Accumulated Other Comprehensive Income
Cost of sales	0	1	(2)	3
Cash flow hedging instruments gains (losses) | Interest rate swap contracts | Reclassifications out of Accumulated Other Comprehensive Income Attributable to 3M
Amount Reclassified from Accumulated Other Comprehensive Income
Interest expense	$ (1)	$ 0	$ (2)	$ 0