Defined Benefit Postretirement Plans and Defined Contribution Plan - Cash Flows (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2019
Defined Benefit Plan Estimated Future Benefit Payments [Line Items]
Employer discretionary contribution amount	$ 22	$ 20	$ 20
Scenario, Forecast [Member]
Defined Benefit Plan Estimated Future Benefit Payments [Line Items]
Estimated future employer contributions in 2019				$ 50
UNITED STATES
Defined Benefit Plan Estimated Future Benefit Payments [Line Items]
2019	38
2020	34
2021	31
2022	29
2023	27
2024 through 2028	114
Foreign Plan [Member]
Defined Benefit Plan Estimated Future Benefit Payments [Line Items]
2019	18
2020	18
2021	20
2022	21
2023	23
2024 through 2028	127
Unfunded Plans [Member] | Scenario, Forecast [Member]
Defined Benefit Plan Estimated Future Benefit Payments [Line Items]
Estimated future employer contributions in 2019				5
Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan Estimated Future Benefit Payments [Line Items]
2019	18
2020	18
2021	9
2022	8
2023	7
2024 through 2028	$ 27
Other Postretirement Benefit Plans, Defined Benefit [Member] | Scenario, Forecast [Member]
Defined Benefit Plan Estimated Future Benefit Payments [Line Items]
Estimated future employer contributions in 2019				$ 18