Defined Benefit Postretirement Plans and Defined Contribution Plan (Cash Flows)(Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plan Estimated Future Benefit Payments [Line Items]
Defined Contribution Plan, Employer Discretionary Contribution Amount		$ 20	$ 20	$ 25
Scenario, Forecast [Member]
Defined Benefit Plan Estimated Future Benefit Payments [Line Items]
Defined Benefit Plan, Estimated Future Employer Contributions in Next Fiscal Year	$ 60
United States Pension Plans of US Entity, Defined Benefit [Member]
Defined Benefit Plan Estimated Future Benefit Payments [Line Items]
Defined Benefit Plan, Expected Future Benefit Payments, Next Twelve Months		34
Defined Benefit Plan, Expected Future Benefit Payments, Year Two		35
Defined Benefit Plan, Expected Future Benefit Payments, Year Three		34
Defined Benefit Plan, Expected Future Benefit Payments, Year Four		35
Defined Benefit Plan, Expected Future Benefit Payments, Year Five		34
Defined Benefit Plan, Expected Future Benefit Payments, Five Fiscal Years Thereafter		163
Foreign Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Estimated Future Benefit Payments [Line Items]
Defined Benefit Plan, Expected Future Benefit Payments, Next Twelve Months		17
Defined Benefit Plan, Expected Future Benefit Payments, Year Two		17
Defined Benefit Plan, Expected Future Benefit Payments, Year Three		18
Defined Benefit Plan, Expected Future Benefit Payments, Year Four		18
Defined Benefit Plan, Expected Future Benefit Payments, Year Five		20
Defined Benefit Plan, Expected Future Benefit Payments, Five Fiscal Years Thereafter		116
Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan Estimated Future Benefit Payments [Line Items]
Defined Benefit Plan, Expected Future Benefit Payments, Next Twelve Months		21
Defined Benefit Plan, Expected Future Benefit Payments, Year Two		21
Defined Benefit Plan, Expected Future Benefit Payments, Year Three		20
Defined Benefit Plan, Expected Future Benefit Payments, Year Four		19
Defined Benefit Plan, Expected Future Benefit Payments, Year Five		19
Defined Benefit Plan, Expected Future Benefit Payments, Five Fiscal Years Thereafter		$ 78
Other Postretirement Benefit Plans, Defined Benefit [Member] | Scenario, Forecast [Member]
Defined Benefit Plan Estimated Future Benefit Payments [Line Items]
Defined Benefit Plan, Estimated Future Employer Contributions in Next Fiscal Year	21
Unfunded Plans [Member] | Scenario, Forecast [Member]
Defined Benefit Plan Estimated Future Benefit Payments [Line Items]
Defined Benefit Plan, Estimated Future Employer Contributions in Next Fiscal Year	$ 5