Pension and Postretirement Benefit Plans - Effect of One-Percentage-Point Change in Assumed Health Care Cost Trend Rates (Details) - Other Postretirement Benefits Plan [Member] - Foreign Plan [Member] $ in Millions	12 Months Ended
	Dec. 31, 2017 USD ($)
Defined Benefit Plan Disclosure [Line Items]
Effect on total of service and interest cost components one percentage point increase	$ 1
Effect on OPEB obligations one percentage point increase	10
Effect on total of service and interest cost components one percentage point decrease	(1)
Effect on OPEB obligations one percentage point decrease	$ (9)