Quarterly report pursuant to Section 13 or 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
Sep. 30, 2013
Dec. 31, 2012
Derivative [Line Items]    
Derivative Asset, Fair Value, Net $ 36 $ 1,924
Derivative Liability, Fair Value, Net (1,157) (241)
Derivative, Fair Value, Net (1,121) 1,683
Natural gas [Member] | Current Liabilities - Fair Market Value of Derivatives [Member]
   
Derivative [Line Items]    
Derivative Asset, Fair Value, Gross Liability 0 0
Derivative Liability, Fair Value, Gross Liability (45) (125)
Derivative Assets (Liability), Fair Value, Gross Liability Net (45) (125)
Natural gas [Member] | Non-current liabilities - Other long-term liabilities [Member]
   
Derivative [Line Items]    
Derivative Asset, Fair Value, Gross Liability 0 0
Derivative Liability, Fair Value, Gross Liability (18) (116)
Derivative Assets (Liability), Fair Value, Gross Liability Net (18) (116)
Crude oil [Member] | Current assets - Fair market value of derivatives [Member]
   
Derivative [Line Items]    
Derivative Asset, Fair Value, Gross Asset 0 1,674
Derivative Liability, Fair Value, Gross Asset (1,094) 0
Derivative Assets (Liability), Fair Value, Gross Asset Net (1,094) 1,674
Crude oil [Member] | Noncurrent Assets - Other Long-Term Assets [Member]
   
Derivative [Line Items]    
Derivative Asset, Fair Value, Gross Asset 36 250
Derivative Liability, Fair Value, Gross Asset 0 0
Derivative Assets (Liability), Fair Value, Gross Asset Net $ 36 $ 250