INVENTORIES (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Inventory Disclosure [Abstract]
Coal stockpiles	$ 61,663	$ 543
Coal fuel inventories	5,319	6,161
Materials and supplies	86,946	34,233
Reserve for obsolete inventory	(774)	(965)
Total	$ 153,154	$ 39,972

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

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Amount before last-in first-out (LIFO) and valuation reserves of ore stockpile material contained on a leach pad, for example, but not limited to, copper or gold ore.

+ References

No definition available.

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Gross amount of unprocessed materials to be used in manufacturing or production process and supplies that will be consumed.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

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Amount of valuation reserve for inventory.

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