Coal Trading (Details 2) (Coal Trading [Member], Credit Concentration Risk [Member], Coal Trading Positions [Member])	Sep. 30, 2011
External Credit Rating, Investment Grade [Member]
Concentration Risk [Line Items]
Concentration Risk, Percentage	35.00%
External Credit Rating, Non Investment Grade [Member]
Concentration Risk [Line Items]
Concentration Risk, Percentage	54.00%
Non Rated [Member]
Concentration Risk [Line Items]
Concentration Risk, Percentage	11.00%

For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

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

-Publisher FASB

-Name Accounting Standards Codification

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-Section 50

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

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-Name Accounting Standards Codification

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Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

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Reference 4: http://www.xbrl.org/2003/role/presentationRef

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Data Type:	num:percentItemType
Balance Type:	na
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