Income Taxes (Narrative) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended			12 Months Ended			24 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013 Brazilian Federal Revenue Service [Member] assessment	Dec. 31, 2007 Brazilian Federal Revenue Service [Member]	Dec. 31, 2006 Brazilian Federal Revenue Service [Member]	Dec. 31, 2004 Brazilian Federal Revenue Service [Member]	Jun. 30, 2005 Argentine Tax Authorities [Member]
Income Taxes [Line Items]
Effective income tax rate	28.70%	29.60%	28.30%	29.10%
Number of separate tax assessments					3
Tax assessment received consisting of tax, penalty, and interest						$ 79	$ 19	$ 446	$ 51
Estimated further assessments that could be received					$ 96