Physical Delivery Contracts and Gas Derivatives (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended	9 Months Ended
Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Commodity derivative contracts:
Unrealized losses			$ 14	$ 438
Commodity derivative contracts [Member]
Commodity derivative contracts:
Realized (losses) gains	(79)	112	(176)	430
Unrealized losses	(186)	(261)	(14)	(438)
Total realized and unrealized losses, net	$ (265)	$ (149)	$ (190)	$ (8)

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Amount of increase (decrease) in the fair value of derivatives recognized in the income statement.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 4A

-Subparagraph (b)

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-Subparagraph (a),(c),(d),(e)

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- Definition

The difference between the book value and the sale price of options, swaps, futures, forward contracts, and other derivative instruments. This element refers to the gain (loss) included in earnings.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

-Subparagraph (b)

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-Publisher FASB

-Name Accounting Standards Codification

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-Subparagraph (SX 210.9-04.13(h))

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The net change in the difference between the fair value and the carrying value, or in the comparative fair values, of derivative instruments, including options, swaps, futures, and forward contracts, held at each balance sheet date, that was included in earnings for the period.

+ References

+ Details

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