Debt and Financing Costs (Details) (USD $) In Millions	Sep. 30, 2011	Dec. 31, 2010
Carrying amounts and estimated fair values of the Company's debt
Carrying Amount, Money market lines of credit	$ 17	$ 46
Carrying Amount, Commercial paper	0	913
Carrying Amount	7,202	8,141
Fair Value	8,415	8,829
Money Market Lines Of Credit [Member]
Carrying amounts and estimated fair values of the Company's debt
Fair Value	17	46
Commercial Paper [Member]
Carrying amounts and estimated fair values of the Company's debt
Fair Value	0	913
Notes And Debentures [Member]
Carrying amounts and estimated fair values of the Company's debt
Carrying Amount	7,185	7,182
Fair Value	$ 8,398	$ 7,870

Investment in short-term money-market instruments (such as commercial paper, banker's acceptances, repurchase agreements, government securities, certificates of deposit, and so forth) which are highly liquid (that is, readily convertible to known amounts of cash) and so near their maturity that they present an insignificant risk of changes in value because of changes in interest rates. Generally, only investments with original maturities of three months or less qualify as cash equivalents by definition. Original maturity means an original maturity to the entity holding the investment. For example, both a three-month US Treasury bill and a three-year Treasury note purchased three months from maturity qualify as cash equivalents. However, a Treasury note purchased three-years ago does not become a cash equivalent when its remaining maturity is three months.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 95

-Paragraph 8, 9

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Cash Equivalents

-URI http://asc.fasb.org/extlink&oid=6507016

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Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant