Fair Value Disclosures (Details) - Natural Gas Swap - Recurring - Level 2 - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	$ 100
Derivative liability		$ 100
Tax on derivative instruments	$ 100	$ 30

Amount of deferred tax liability attributable to taxable temporary differences from derivatives.

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+ References

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