Income Taxes (Narrative) (Details) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019 USD ($) assessment	Jun. 30, 2018	Jun. 30, 2019 USD ($) assessment	Jun. 30, 2018
Income Tax Contingency [Line Items]
Effective income tax rate	13.10%	13.20%	19.90%	13.80%
Brazilian Federal Revenue Service [Member]
Income Tax Contingency [Line Items]
Number of separate tax assessments | assessment	3		3
Income tax assessment	$ 110		$ 110
Income tax assessment - Interest and Penalties	317		317
Argentine Tax Authorities [Member]
Income Tax Contingency [Line Items]
Income tax assessment	20		20
Income tax assessment - Interest and Penalties	69		69
Estimated Additional Tax Assessment	56		56
Additional income tax assessment - Interest and Penalties	53		53
Tax and Customs Administration, Netherlands [Member]
Income Tax Contingency [Line Items]
Income tax assessment	92		92
Additional income tax assessment - Interest and Penalties	$ 33		$ 33