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Derivative Instruments (Details Textual) (USD $)
3 Months Ended 3 Months Ended
Mar. 31, 2014
Dec. 31, 2013
Mar. 31, 2013
Dec. 31, 2012
Mar. 31, 2014
Gas hedges [Member]
Mar. 31, 2013
Gas hedges [Member]
Mar. 31, 2014
Crude Oil [Member]
Mar. 31, 2013
Crude Oil [Member]
Derivative Instruments (Textual) [Abstract]                
Gain or loss recognized in oil and gas contracts         $ (3,000,000) $ 500,000 $ (400,000) $ (100,000)
Accumulated other comprehensive loss (4,514,000) (1,096,000) (3,389,000) 521,000        
Realization of gain, net of taxes $ (2,800,000)