Long-Term Employee Benefits (Contributions) (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Pension Plan Other Than Principal Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Employer contributions		$ 121	$ 164
Other Post Employment Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Employer contributions		218	237
Remaining pension plans with no plan assets [Member]
Defined Benefit Plan Disclosure [Line Items]
Employer contributions		184	144
U.S. Pension Plan Trust Fund [Member]
Defined Benefit Plan Disclosure [Line Items]
Employer contributions		$ 230	$ 0	$ 0
Scenario, Forecast [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Contribution Plan Estimated Future Employer Contributions In Next Fiscal Year	about the same
Scenario, Forecast [Member] | Pension Plan Other Than Principal Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plans, Estimated Future Employer Contributions in Next Fiscal Year	$ 95
Scenario, Forecast [Member] | Other Post Employment Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plans, Estimated Future Employer Contributions in Next Fiscal Year	275
Scenario, Forecast [Member] | Remaining pension plans with no plan assets [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plans, Estimated Future Employer Contributions in Next Fiscal Year	$ 85
Scenario, Forecast [Member] | U.S. Pension Plan Trust Fund [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plans, Estimated Future Employer Contributions in Next Fiscal Year	about the same