Income Taxes (Narrative) (Details) $ in Millions	3 Months Ended
	Mar. 31, 2019 USD ($) assessment	Mar. 31, 2018
Income Tax Contingency [Line Items]
Effective income tax rate	25.70%	14.70%
Brazilian Federal Revenue Service [Member]
Income Tax Contingency [Line Items]
Number of separate tax assessments | assessment	3
Income tax assessment	$ 108
Income tax assessment - Interest and Penalties	309
Argentine Tax Authorities [Member]
Income Tax Contingency [Line Items]
Income tax assessment	15
Income tax assessment - Interest and Penalties	55
Estimated Additional Tax Assessment	52
Additional income tax assessment - Interest and Penalties	58
Tax and Customs Administration, Netherlands [Member]
Income Tax Contingency [Line Items]
Income tax assessment	91
Additional income tax assessment - Interest and Penalties	$ 31