FAIR VALUE OF FINANCIAL ASSETS AND FINANCIAL LIABILITIES (Details) (Fair Value, Measurements, Recurring [Member], USD $) In Thousands, unless otherwise specified	Mar. 31, 2014		Dec. 31, 2013
Total [Member]
Assets [Abstract]
Available-for-sale Securities	$ 8,808	[1]	$ 8,696	[1]
Derivatives - Energy Related Assets	2,190	[2]	1,500	[2]
Total Assets	10,998		10,196
Liabilities [Abstract]
Derivatives - Energy Related Liabilities	466	[2]	759	[2]
Derivatives - Other	4,735	[3]	3,735	[3]
Total Liabilities	5,201		4,494
Level 1 [Member]
Assets [Abstract]
Available-for-sale Securities	8,808	[1]	8,696	[1]
Derivatives - Energy Related Assets	2,190	[2]	1,409	[2]
Total Assets	10,998		10,105
Liabilities [Abstract]
Derivatives - Energy Related Liabilities	466	[2]	155	[2]
Derivatives - Other	0	[3]	0	[3]
Total Liabilities	466		155
Level 2 [Member]
Assets [Abstract]
Available-for-sale Securities	0	[1]	0	[1]
Derivatives - Energy Related Assets	0	[2]	91	[2]
Total Assets	0		91
Liabilities [Abstract]
Derivatives - Energy Related Liabilities	0	[2]	604	[2]
Derivatives - Other	4,735	[3]	3,735	[3]
Total Liabilities	4,735		4,339
Level 3 [Member]
Assets [Abstract]
Available-for-sale Securities	0	[1]	0	[1]
Derivatives - Energy Related Assets	0	[2]	0	[2]
Total Assets	0		0
Liabilities [Abstract]
Derivatives - Energy Related Liabilities	0	[2]	0	[2]
Derivatives - Other	0	[3]	0	[3]
Total Liabilities	$ 0		$ 0

[1] Available-for-Sale Securities include securities that are traded in active markets and securities that are not traded publicly. The securities traded in active markets are valued using the quoted principal market close prices that are provided by the trustees and are categorized in Level 1 in the fair value hierarchy. The remaining securities consisted of funds that are not publicly traded. These funds, which consisted of stocks and bonds that are traded individually in active markets, are valued using quoted prices for similar assets and are categorized in Level 2 in the fair value hierarchy.

[2] Derivatives – Energy Related Assets and Liabilities are traded in both exchange-based and non-exchange-based markets. Exchange-based contracts are valued using unadjusted quoted market sources in active markets and are categorized in Level 1 in the fair value hierarchy. Certain non-exchange-based contracts are valued using indicative price quotations available through brokers or over-the-counter, on-line exchanges and are categorized in Level 2. These price quotations reflect the average of the bid-ask mid-point prices and are obtained from sources that management believes provide the most liquid market. Management reviews and corroborates the price quotations to ensure the prices are observable which includes consideration of actual transaction volumes, market delivery points, bid-ask spreads and contract duration. In instances where observable data is unavailable, management considers the assumptions that market participants would use in valuing the asset or liability. This includes assumptions about market risks such as liquidity, volatility and contract duration. Such instruments are categorized in Level 3 as the model inputs generally are not observable. Level 3 valuation methods for natural gas derivative contracts include utilizing another location in close proximity adjusted for certain pipeline charges to derive a basis value.Significant Unobservable Inputs - Management uses the discounted cash flow model to value Level 3 physical forwards, which calculates mark-to-market valuations based on forward prices, original transaction prices, volumes, risk-free rate of return and credit spreads. Inputs to the valuation model are reviewed and revised as needed, based on historical information, updated market data, market liquidity and relationships, and changes in third party pricing sources. The significant unobservable inputs used in the fair value measurement of certain natural gas contracts are forward prices developed based on industry standard methodologies. Significant increases (decreases) in these forward prices for purchases of natural gas would result in a directionally similar impact to the fair value measurement and for sales of natural gas would result in a directionally opposite impact to the fair value measurement. The validity of the mark-to-market valuations and changes in mark-to-market valuations from period to period are examined and qualified against historical expectations by the risk management function. If any discrepancies are identified during this process, the mark-to-market valuations or the market pricing information is evaluated further and adjusted, if necessary.

[3] Derivatives – Other, include interest rate swaps that are valued using quoted prices on commonly quoted intervals, which are interpolated for periods different than the quoted intervals, as inputs to a market valuation model. Market inputs can generally be verified and model selection does not involve significant management judgment.