Pensions Benefit Plans and Other Postretirement Benefits - Funded Status (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Pension Benefit Plans
Defined Benefit Plan Disclosure
Percentage of minimum target plan asset allocations	10.00%
U.S. Pension Plans
Defined Benefit Plan Disclosure
Plan assets at fair value	$ 1,394	$ 1,654	$ 1,909
Projected benefit and postretirement benefit obligations	1,650	1,956	2,190
Plan assets less than projected benefit obligations	(256)	(302)
Items not yet recognized in pension expense and net postretirement benefit cost:
Actuarial loss	811	1,046
Prior service cost (credit)	1	1
Total	812	1,047
Net amount recognized	556	745
Non-U.S. Pension Plans
Defined Benefit Plan Disclosure
Plan assets at fair value	975	1,011	1,012
Projected benefit and postretirement benefit obligations	1,148	1,235	1,210
Plan assets less than projected benefit obligations	(173)	(224)
Items not yet recognized in pension expense and net postretirement benefit cost:
Actuarial loss	284	352
Prior service cost (credit)	(2)	(1)
Total	282	351
Net amount recognized	109	127
U.S Postretirement Benefit Plans
Defined Benefit Plan Disclosure
Projected benefit and postretirement benefit obligations	89	92	97
Items not yet recognized in pension expense and net postretirement benefit cost:
Actuarial loss	(19)	(21)
Prior service cost (credit)	22	30
Total	3	9
Net amount recognized	(86)	(83)
Non-U.S. Postretirement Benefit Plans
Defined Benefit Plan Disclosure
Projected benefit and postretirement benefit obligations	89	81	$ 68
Items not yet recognized in pension expense and net postretirement benefit cost:
Actuarial loss	(7)	(6)
Total	(7)	(6)
Net amount recognized	$ (96)	$ (87)