Contingencies (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2012 Lawsuit
Loss Contingencies [Line Items]
Lawsuit alleges damages	$ 28
Contingencies (Textual) [Abstract]
Number of lawsuits alleging damages	2
Area of operation	Louisiana
Other [Member]
Loss Contingencies [Line Items]
Lawsuit alleges damages	$ 9

The value (monetary amount) of the award the plaintiff seeks in the legal matter.

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-Name Accounting Standards Codification

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-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

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-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 7: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 5

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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.

+ Details

- Definition

Identifies the geographic areas in which the damages were alleged to have occurred.

+ References+ Details