Short-Term Borrowings (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Short-term Debt
Short-term borrowings, Balance	$ 3,663	$ 4,651	$ 3,895
Commercial paper, net
Short-term Debt
Short-term borrowings, Balance	2,502	3,654	2,818
Short-term borrowings, Avg. Rate	0.50%	0.60%	1.00%
Bank borrowings
Short-term Debt
Short-term borrowings, Balance	545	418	527
Short-term borrowings, Avg. Rate	6.40%	5.60%	7.30%
Variable denomination floating rate demand notes
Short-term Debt
Short-term borrowings, Balance	$ 616	$ 579	$ 550
Short-term borrowings, Avg. Rate	0.80%	0.80%	0.90%