Derivative and Hedging Instruments (Details-3) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Commodity Derivative Contracts [Member]
Offsetting Liabilities [Line Items]
Gross amounts	$ 682	$ 218
Gross amounts offset in balance sheet	(634)	(218)
Collateral posted against derivative positions	0	0
Net amount presented in balance sheet	48	0
Purchased Power Agreement [Member]
Offsetting Liabilities [Line Items]
Gross amounts	43,130	50,590
Gross amounts offset in balance sheet	0	0
Collateral posted against derivative positions	0	0
Net amount presented in balance sheet	$ 43,130	$ 50,590

Fair value, before effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities elected not to be offset. Excludes liabilities not subject to a master netting arrangement.

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Fair value, after the effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities not subject to a master netting arrangement and not elected to be offset.

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Amount of right to receive cash collateral under master netting arrangements offset against derivative liabilities.

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Fair value of asset associated with financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset.

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No definition available.

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