Annual report pursuant to Section 13 and 15(d)

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

v2.4.0.8
Derivative Instruments and Hedging Activities (Derivatives Fair Value By Balance Sheet Location) (Details) (Not Designated as Hedging Instrument [Member], USD $)
In Thousands, unless otherwise specified
Dec. 31, 2013
Dec. 31, 2012
Derivative [Line Items]    
Derivative Asset, Fair Value, Amount Not Offset Against Collateral $ 60 $ 1,924
Derivative Liability, Fair Value, Amount Not Offset Against Collateral (1,108) (241)
Derivative, Fair Value, Net (1,048) 1,683
Current liabilities - Fair market value of derivatives [Member]
   
Derivative [Line Items]    
Derivative Assets (Liability), Fair Value, Gross Asset Net 60  
Derivative Assets (Liability), Fair Value, Gross Liability Net 1,036  
Derivative Asset, Fair Value, Amount Not Offset Against Collateral 8  
Derivative Liability, Fair Value, Amount Not Offset Against Collateral 1,088  
Current liabilities - Fair market value of derivatives [Member] | Natural gas [Member]
   
Derivative [Line Items]    
Derivative Asset, Fair Value, Gross Asset 60  
Derivative Asset, Fair Value, Gross Liability   0
Derivative Liability, Fair Value, Gross Asset 0  
Derivative Liability, Fair Value, Gross Liability   (125)
Derivative Assets (Liability), Fair Value, Gross Asset Net 60  
Derivative Assets (Liability), Fair Value, Gross Liability Net   (125)
Non-current liabilities - Other long-term liabilities [Member]
   
Derivative [Line Items]    
Derivative Assets (Liability), Fair Value, Gross Liability Net (72)  
Derivative Liability, Fair Value, Amount Not Offset Against Collateral (72)  
Non-current liabilities - Other long-term liabilities [Member] | Natural gas [Member]
   
Derivative [Line Items]    
Derivative Asset, Fair Value, Gross Liability 0 0
Derivative Liability, Fair Value, Gross Liability (72) (116)
Derivative Assets (Liability), Fair Value, Gross Liability Net (72) (116)
Current assets - Fair market value of derivatives [Member] | Crude oil [Member]
   
Derivative [Line Items]    
Derivative Asset, Fair Value, Gross Asset   1,674
Derivative Asset, Fair Value, Gross Liability 0  
Derivative Liability, Fair Value, Gross Asset   0
Derivative Liability, Fair Value, Gross Liability (1,036)  
Derivative Assets (Liability), Fair Value, Gross Asset Net   1,674
Derivative Assets (Liability), Fair Value, Gross Liability Net (1,036)  
Non-current assets - Other long-term assets [Member]
   
Derivative [Line Items]    
Derivative Assets (Liability), Fair Value, Gross Asset Net 0  
Derivative Asset, Fair Value, Amount Not Offset Against Collateral 0  
Non-current assets - Other long-term assets [Member] | Crude oil [Member]
   
Derivative [Line Items]    
Derivative Asset, Fair Value, Gross Asset 0 250
Derivative Liability, Fair Value, Gross Asset 0 0
Derivative Assets (Liability), Fair Value, Gross Asset Net $ 0 $ 250