INVENTORIES (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
INVENTORIES
Coal	$ 22,825	$ 29,242
Supplies (net of reserve for obsolescence of $5,149 and $4,940, respectively)	37,450	31,809
Total inventories, net	60,275	61,051
Reserve for obsolescence	$ 5,149	$ 4,940

Carrying amount as of the balance sheet date of coal, which is a combustible rock or minerals which are extracted from the ground and used as fuel.

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- References

No definition available.

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- Definition

Amount after valuation and LIFO reserves of inventory expected to be sold, or consumed within one year or operating cycle, if longer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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- Definition

Carrying amount, net of valuation reserves and adjustments, as of the balance sheet date of products used directly or indirectly in the manufacturing or production process, which may or may not become part of the final product. May also include items used in the storage, presentation or transportation of physical goods.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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- Definition

Amount of valuation reserve for inventory.

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