Income Taxes (Narrative) (Details) $ in Millions	3 Months Ended
	Mar. 31, 2016 USD ($) assessment	Mar. 31, 2015
Income Tax Contingency [Line Items]
Effective income tax rate	24.80%	28.60%
Brazilian Federal Revenue Service [Member]
Income Tax Contingency [Line Items]
Number of separate tax assessments | assessment	3
Income tax assessment	$ 401
Argentine Tax Authorities [Member]
Income Tax Contingency [Line Items]
Income tax assessment	112
Estimated Additional Tax Assessment	$ 152