Supplemental Equity and Comprehensive Income Information - Reclass AOCI (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Amount Reclassified from Accumulated Other Comprehensive Income
Net of tax	$ (82)	$ (52)	$ (228)	$ (137)
Gains (losses) associated with defined benefit pension and postretirement plans amortization
Amount Reclassified from Accumulated Other Comprehensive Income
Transition asset				1
Prior service benefit	21	22	65	69
Net actuarial loss	(140)	(125)	(422)	(377)
Total before tax	(119)	(103)	(357)	(307)
Tax effect	39	36	116	104
Net of tax	(80)	(67)	(241)	(203)
Cash flow hedging instruments gains (losses)
Amount Reclassified from Accumulated Other Comprehensive Income
Total before tax	(2)	24	21	104
Tax effect		(9)	(8)	(38)
Net of tax	(2)	15	13	66
Cash flow hedging instruments gains (losses) | Foreign currency forward/option contracts
Amount Reclassified from Accumulated Other Comprehensive Income
Cost of sales	$ (2)	$ 24	$ 21	105
Cash flow hedging instruments gains (losses) | Interest rate swap contracts
Amount Reclassified from Accumulated Other Comprehensive Income
Interest expense				$ (1)