Summary of Significant Accounting Policies - Inventories (Details 6) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Summary Of Significant Accounting Policies [Abstract]
Finished Goods	$ 22,012	$ 21,893
Work in Process	9,739	8,800
Raw Material, Fuel and Supplies	41,660	38,643
Total Inventories	$ 73,411	$ 69,336

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Carrying amount, net of valuation reserves and adjustments, as of the balance sheet date of merchandise or goods held by the company that are readily available for sale.

+ References

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-Publisher FASB

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-Subparagraph (SAB TOPIC 5.BB)

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-Name Regulation S-X (SX)

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Carrying amount (lower of cost or market) as of the balance sheet date of inventories less all valuation and other allowances. Excludes noncurrent inventory balances (expected to remain on hand past one year or one operating cycle, if longer).

+ References

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

+ References

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-Publisher SEC

-Name Regulation S-X (SX)

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Gross amount of merchandise or goods which are partially completed, are generally comprised of raw materials, labor and factory overhead costs, and which require further materials, labor and overhead to be converted into finished goods, and which generally require the use of estimates to determine percentage complete and pricing.

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