Quarterly report pursuant to Section 13 or 15(d)

Derivative Instruments and Hedging Activities (Derivatives Fair Value By Balance Sheet Location) (Details)

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Derivative Instruments and Hedging Activities (Derivatives Fair Value By Balance Sheet Location) (Details) (USD $)
In Thousands, unless otherwise specified
Sep. 30, 2014
Dec. 31, 2013
Derivatives, Fair Value [Line Items]    
Asset Fair Value $ 6,011 $ 60
Liability Fair Value (1,330) (1,108)
Net Derivative Fair Value 4,681 (1,048)
Not Designated as Hedging Instrument [Member]
   
Derivatives, Fair Value [Line Items]    
Asset Fair Value 6,011 60
Liability Fair Value (1,330) (1,108)
Net Derivative Fair Value 4,681 (1,048)
Current liabilities - Fair market value of derivatives [Member] | Not Designated as Hedging Instrument [Member] | Natural Gas [Member]
   
Derivatives, Fair Value [Line Items]    
Liability Fair Value (47)  
Net Derivative Fair Value (47)  
Current liabilities - Fair market value of derivatives [Member] | Not Designated as Hedging Instrument [Member] | Crude Oil [Member]
   
Derivatives, Fair Value [Line Items]    
Liability Fair Value (418) (1,036)
Non-current liabilities - Other long-term liabilities [Member] | Not Designated as Hedging Instrument [Member] | Natural Gas [Member]
   
Derivatives, Fair Value [Line Items]    
Liability Fair Value (41) (72)
Net Derivative Fair Value (41) (72)
Non-current liabilities - Other long-term liabilities [Member] | Not Designated as Hedging Instrument [Member] | Crude Oil [Member]
   
Derivatives, Fair Value [Line Items]    
Liability Fair Value (824)  
Net Derivative Fair Value (824)  
Current assets - Fair market value of derivatives [Member] | Not Designated as Hedging Instrument [Member] | Natural Gas [Member]
   
Derivatives, Fair Value [Line Items]    
Asset Fair Value   60
Net Derivative Fair Value   60
Current assets - Fair market value of derivatives [Member] | Not Designated as Hedging Instrument [Member] | Crude Oil [Member]
   
Derivatives, Fair Value [Line Items]    
Asset Fair Value 4,842  
Non-current assets - Other long-term assets [Member] | Not Designated as Hedging Instrument [Member] | Crude Oil [Member]
   
Derivatives, Fair Value [Line Items]    
Asset Fair Value 1,169  
Net Derivative Fair Value 1,169  
Balance Sheet Current [Member] | Not Designated as Hedging Instrument [Member] | Crude Oil [Member]
   
Derivatives, Fair Value [Line Items]    
Net Derivative Fair Value $ 4,424 $ (1,036)