RISK MANAGEMENT AND DERIVATIVE FINANCIAL INSTRUMENTS (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Fair value of derivative financial instruments
Current assets	$ 1,466us-gaap_DerivativeInstrumentsAndHedges	$ 3,901us-gaap_DerivativeInstrumentsAndHedges
Total derivatives assets	1,466	3,901
Current liabilities	6,685	6,469
Non-current liabilities and deferred credits	4,488us-gaap_DerivativeLiabilitiesNoncurrent	3,243us-gaap_DerivativeLiabilitiesNoncurrent
Total derivatives liabilities	11,173	9,712
Hedging instruments \| Commodity contracts \| Gas
Fair value of derivative financial instruments
Current liabilities	171	476
Hedging instruments \| Commodity contracts \| Electric
Fair value of derivative financial instruments
Current assets		1
Current liabilities	6,514	5,993
Non-current liabilities and deferred credits	4,488	3,243
Hedging instruments \| Transmission congestion rights (TCR) \| Electric
Fair value of derivative financial instruments
Current assets	$ 1,466	$ 3,900

Fair value, before effects of master netting arrangements, of a financial asset or other 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 assets elected not to be offset. Excludes assets not subject to a master netting arrangement.

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Carrying amount as of the balance sheet date of the asset arising from derivative instruments and hedging activities, which are expected to be converted into cash or otherwise disposed of within a year or the normal operating cycle, if longer.

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