Investments, Loans and Long-Term Receivables (Summary of Financial Information for Equity Method Investments) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Summary of financial information
Revenues	$ 59,500	$ 55,401	$ 59,044
Income before income taxes	5,975	6,265	6,083
Net income	5,838	6,122	5,742
Current assets	9,865	9,646	8,752
Noncurrent assets	40,188	37,269	34,329
Current liabilities	7,971	8,319	6,837
Noncurrent liabilities	$ 9,959	$ 9,251	$ 10,279