Income Taxes (Narrative) (Details) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015 USD ($) assessment	Jun. 30, 2014	Jun. 30, 2015 USD ($) assessment	Jun. 30, 2014
Income Taxes [Line Items]
Effective income tax rate	27.20%	27.60%	28.00%	27.30%
Brazilian Federal Revenue Service [Member]
Income Taxes [Line Items]
Number of separate tax assessments | assessment	3		3
Estimated Tax Assessment Including Penalties and Interest	$ 436		$ 436
Estimated Additional Tax Assessment	50		50
Argentine Tax Authorities [Member]
Income Taxes [Line Items]
Estimated Additional Tax Assessment	284		284
Estimated Tax Assessment Including Interest	$ 92		$ 92