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Debt (Details) - USD ($) $ in Thousands		6 Months Ended	12 Months Ended
		Jun. 30, 2015	Dec. 31, 2014
Schedule of Debt Instruments [Line Items]
Industrial revenue bonds		$ 7,815	$ 7,815
TOTAL		$ 254,894	$ 254,703
Industrial revenue bonds due 2028 [Member] | Short-term Debt [Member]
Schedule of Debt Instruments [Line Items]
Effective interest rate percentage, minimum	[1]	12.00%	12.00%
Stated interest rate, percentage		0.27%
Industrial revenue bonds	[1]	$ 7,815	$ 7,815
Senior secured notes due June 01, 2021 [Member] | Long-term Debt [Member]
Schedule of Debt Instruments [Line Items]
Maturity date		Jun. 01, 2021	Jun. 01, 2021
Stated interest rate, percentage		7.50%	7.50%
Debt discount		$ 2,921	$ 3,112
Senior secured notes		$ 247,079	$ 246,888
[1] The IRBs are classified as current liabilities because they are remarketed weekly and could be required to be repaid upon demand if there is a failed remarketing. The IRB interest rate at June 30, 2015 was 0.27%.

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Carrying value as of the balance sheet date of the long-term debt associated with industrial revenue bonds. For classified balance sheets, these bonds are considered current assets because they are remarketed weekly and the bonds could be required to be repaid upon demand if there is a failed remarketing.

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When presenting a range of interest rates, the highest effective rate for funds borrowed under the debt agreement as of the balance sheet date.

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Contractual interest rate for funds borrowed, under the debt agreement.

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The amount of debt discount that was originally recognized at the issuance of the instrument that has yet to be amortized.

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Carrying amount of collateralized debt obligations with maturities initially due after one year or beyond the operating cycle, if longer, excluding the current portion. Obligations include, but not limited to, mortgage loans, chattel loans, and other borrowings secured by assets.

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