INVENTORIES (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Inventory Disclosure [Abstract]
Coal	$ 8,853	$ 4,642
Supplies	46,035	44,004
Total Inventories	$ 54,888	$ 48,646

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

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-Publisher FASB
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-SubTopic 10
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- Definition

Carrying amount, net of valuation reserves and adjustments, as of the balance sheet date of unprocessed items to be consumed in the manufacturing or production process.

+ References

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-Publisher FASB
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-SubTopic 10
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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

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-Name Accounting Standards Codification
-Topic 330
-SubTopic 10
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