Employee Benefit Plans - Narrative (Details) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2018 USD ($)	Sep. 30, 2018 USD ($)
Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Expected Future Employer Contributions, Current Fiscal Year	$ 1	$ 1
Defined Benefit Plan Estimated Total Employer Contributions in Current Fiscal Year	2	2
Defined Benefit Plan, Plan Assets, Contributions by Employer	0	1
Postemployment Retirement Benefits [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Expected Future Employer Contributions, Current Fiscal Year	31	31
Defined Benefit Plan Estimated Total Employer Contributions in Current Fiscal Year	60	60
Defined Benefit Plan, Plan Assets, Contributions by Employer	11	29
Foreign Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Expected Future Employer Contributions, Current Fiscal Year	13	13
Defined Benefit Plan Estimated Total Employer Contributions in Current Fiscal Year	30	30
Defined Benefit Plan, Plan Assets, Contributions by Employer	$ 4	$ 17