Income Taxes (Narrative) (Details) $ in Millions	3 Months Ended
	Mar. 31, 2017 USD ($) assessment	Mar. 31, 2016
Income Tax Contingency [Line Items]
Effective income tax rate	25.80%	24.80%
Brazilian Federal Revenue Service [Member]
Income Tax Contingency [Line Items]
Number of separate tax assessments | assessment	3
Income tax assessment	$ 478
Argentine Tax Authorities [Member]
Income Tax Contingency [Line Items]
Income tax assessment	133
Estimated Additional Tax Assessment	218
Tax and Customs Administration, Netherlands [Member]
Income Tax Contingency [Line Items]
Income tax assessment	$ 96