Income Taxes (Narrative) (Details) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016 USD ($) assessment	Jun. 30, 2015	Jun. 30, 2016 USD ($) assessment	Jun. 30, 2015
Income Tax Contingency [Line Items]
Effective income tax rate	29.20%	27.20%	27.30%	28.00%
Brazilian Federal Revenue Service [Member]
Income Tax Contingency [Line Items]
Number of separate tax assessments | assessment	3		3
Income tax assessment	$ 452		$ 452
Argentine Tax Authorities [Member]
Income Tax Contingency [Line Items]
Income tax assessment	112		112
Estimated Additional Tax Assessment	$ 155		$ 155