Income Taxes (Narrative) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Income Taxes [Line Items]
Effective income tax rate	28.60%	26.80%
Brazilian Federal Revenue Service [Member]
Income Taxes [Line Items]
Number of separate tax assessments	3
Estimated Tax Assessment Including Penalties and Interest	415
Estimated Additional Tax Assessment	48
Argentine Tax Authorities [Member]
Income Taxes [Line Items]
Estimated Additional Tax Assessment	329
Estimated Tax Assessment Including Interest	93