Physical Delivery Contracts and Gas Derivatives (Details 1) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Derivative contracts:
Derivative assets	$ 131	$ 308
Commodity derivative contracts [Member] \| Natural Gas [Member] \| Not Designated as Hedging Instrument [Member]
Derivative contracts:
Derivative assets	131	308
Current liabilities

Fair values as of the balance sheet date for all assets resulting from contracts that meet the criteria of being accounted for as derivative instruments and which are expected to be converted into cash or otherwise disposed of within a year or the normal operating cycle, if longer, net of the effects of master netting arrangements.

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+ Details

- Definition

Fair values as of the balance sheet date of all liabilities resulting from contracts that meet the criteria of being accounted for as derivative instruments, and which are expected to be extinguished or otherwise disposed of within a year or the normal operating cycle, if longer, net of the effects of master netting arrangements.

+ References

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+ Details