Long-term Debt - Principal payments under the Energy Credit Agreement (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Debt Disclosure [Abstract]
Remainder of 2014	$ 9,911
2015	13,214
2016	13,214
2017	13,214
2018	39,643
Total	89,196
Less current portion	13,214	13,214
Total long-term debt	$ 75,982	$ 79,286

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