Annual report pursuant to Section 13 and 15(d)

Derivative Financial Instruments (Schedule Of Derivative Liabilities At Fair Value) (Details)

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Derivative Financial Instruments (Schedule Of Derivative Liabilities At Fair Value) (Details) (USD $)
In Thousands, unless otherwise specified
12 Months Ended
Dec. 31, 2011
Commodity Option Contracts [Member]
 
Derivatives, Fair Value [Line Items]  
Notional Quantity (Bbls) 1,103,000
Weighted Average Floor Contract Price 75.00
Weighted Average Ceiling Contract Price 98.13
Fair Value Liability $ 7,199
Oil Swap Contracts [Member]
 
Derivatives, Fair Value [Line Items]  
Notional Quantity (Bbls) 3,078,200
Weighted Average Contract Price 102.87
Fair Value Net Asset 4,087
2012: 1st Quarter [Member] | Commodity Option Contracts [Member]
 
Derivatives, Fair Value [Line Items]  
Termination Period 2012: 1st quarter
Notional Quantity (Bbls) 364,000
Weighted Average Floor Contract Price 75.00
Weighted Average Ceiling Contract Price 97.88
Fair Value Liability 1,735
2012: 1st Quarter [Member] | Oil Swap Contracts [Member]
 
Derivatives, Fair Value [Line Items]  
Termination Period 2012: 1st quarter
Notional Quantity (Bbls) 236,600
Weighted Average Contract Price 107.28
Fair Value Net Asset 124
2012: 2nd Quarter [Member] | Commodity Option Contracts [Member]
 
Derivatives, Fair Value [Line Items]  
Termination Period 2nd quarter
Notional Quantity (Bbls) 364,000
Weighted Average Floor Contract Price 75.00
Weighted Average Ceiling Contract Price 97.88
Fair Value Liability 2,707
2012: 2nd Quarter [Member] | Oil Swap Contracts [Member]
 
Derivatives, Fair Value [Line Items]  
Termination Period 2nd quarter
Notional Quantity (Bbls) 200,200
Weighted Average Contract Price 107.28
Fair Value Net Asset 294
2012: 3rd Quarter [Member | Commodity Option Contracts [Member]
 
Derivatives, Fair Value [Line Items]  
Termination Period 3rd quarter
Notional Quantity (Bbls) 124,000
Weighted Average Floor Contract Price 75.00
Weighted Average Ceiling Contract Price 97.88
Fair Value Liability 972
2012: 3rd Quarter [Member | Oil Swap Contracts [Member]
 
Derivatives, Fair Value [Line Items]  
Termination Period 3rd quarter
Notional Quantity (Bbls) 414,000
Weighted Average Contract Price 107.28
Fair Value Net Asset 1,023
2012: 4th Quarter [Member] | Commodity Option Contracts [Member]
 
Derivatives, Fair Value [Line Items]  
Termination Period 4th quarter
Notional Quantity (Bbls) 251,000
Weighted Average Floor Contract Price 75.00
Weighted Average Ceiling Contract Price 98.99
Fair Value Liability 1,785
2012: 4th Quarter [Member] | Oil Swap Contracts [Member]
 
Derivatives, Fair Value [Line Items]  
Termination Period 4th quarter
Notional Quantity (Bbls) 257,600
Weighted Average Contract Price 107.28
Fair Value Net Asset 901
2013: 1st Quarter [Member] | Oil Swap Contracts [Member]
 
Derivatives, Fair Value [Line Items]  
Termination Period 2013: 1st quarter
Notional Quantity (Bbls) 351,000
Weighted Average Contract Price 101.97
Fair Value Net Asset (171)
2013: 2nd Quarter [Member] | Oil Swap Contracts [Member]
 
Derivatives, Fair Value [Line Items]  
Termination Period 2nd quarter
Notional Quantity (Bbls) 336,700
Weighted Average Contract Price 101.97
Fair Value Net Asset 217
2013: 3rd Quarter [Member] | Oil Swap Contracts [Member]
 
Derivatives, Fair Value [Line Items]  
Termination Period 3rd quarter
Notional Quantity (Bbls) 312,800
Weighted Average Contract Price 101.98
Fair Value Net Asset 543
2013: 4th Quarter [Member] | Oil Swap Contracts [Member]
 
Derivatives, Fair Value [Line Items]  
Termination Period 4th quarter
Notional Quantity (Bbls) 294,400
Weighted Average Contract Price 101.98
Fair Value Net Asset 820
2014: 1st Quarter [Member] | Oil Swap Contracts [Member]
 
Derivatives, Fair Value [Line Items]  
Termination Period 2014: 1st quarter
Notional Quantity (Bbls) 180,000
Weighted Average Contract Price 97.38
Fair Value Net Asset (125)
2014: 2nd Quarter [Member] | Oil Swap Contracts [Member]
 
Derivatives, Fair Value [Line Items]  
Termination Period 2nd quarter
Notional Quantity (Bbls) 172,900
Weighted Average Contract Price 97.38
Fair Value Net Asset 39
2014: 3rd Quarter [Member] | Oil Swap Contracts [Member]
 
Derivatives, Fair Value [Line Items]  
Termination Period 3rd quarter
Notional Quantity (Bbls) 165,600
Weighted Average Contract Price 97.38
Fair Value Net Asset 161
2014: 4th Quarter [Member] | Oil Swap Contracts [Member]
 
Derivatives, Fair Value [Line Items]  
Termination Period 4th quarter
Notional Quantity (Bbls) 156,400
Weighted Average Contract Price 97.37
Fair Value Net Asset $ 261