Quarterly report pursuant to Section 13 or 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
3 Months Ended
Mar. 31, 2012
Oil Zero Cost Collars [Member]
 
Derivatives, Fair Value [Line Items]  
Notional Quantity (Bbls) 739,000
Weighted Average Floor Contract Price 75.00
Weighted Average Ceiling Contract Price 98.25
Fair Value Liability $ 6,596
Oil Swap Contracts [Member]
 
Derivatives, Fair Value [Line Items]  
Notional Quantity (Bbls) 3,042,710
Weighted Average Contract Price 103.16
Fair Value Liability 30,350
2012: 2nd Quarter [Member] | Oil Zero Cost Collars [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 2,603
2012: 2nd Quarter [Member] | Oil Swap Contracts [Member]
 
Derivatives, Fair Value [Line Items]  
Termination Period 2nd quarter
Notional Quantity (Bbls) 401,310
Weighted Average Contract Price 109.81
Fair Value Liability 4,619
2012: 3rd Quarter [Member | Oil Zero Cost Collars [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 1,185
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 Liability 4,884
2012: 4th Quarter [Member] | Oil Zero Cost Collars [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 2,808
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 Liability 2,543
2013: 1st Quarter [Member] | Oil Swap Contracts [Member]
 
Derivatives, Fair Value [Line Items]  
Termination Period 1st quarter
Notional Quantity (Bbls) 351,000
Weighted Average Contract Price 101.97
Fair Value Liability 4,563
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 Liability 3,714
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 Liability 2,860
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 Liability 2,149
2014: 1st Quarter [Member] | Oil Swap Contracts [Member]
 
Derivatives, Fair Value [Line Items]  
Termination Period 1st quarter
Notional Quantity (Bbls) 180,000
Weighted Average Contract Price 97.38
Fair Value Liability 1,793
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 Liability 1,405
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 Liability 1,066
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 Liability $ 754