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Derivative Instruments (Schedule Of Outstanding Commodity Derivative Contracts Not Designated As Hedges) (Details) (Crude Oil Collar [Member], USD $) In Thousands, unless otherwise specified |  |  | 12 Months Ended
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Dec. 31, 2011 | Dec. 31, 2010 | Dec. 31, 2011 2012 Two-Way Collars [Member] | Dec. 31, 2011 2012 Three-Way Collars [Member] | Dec. 31, 2011 2012 Deferred Puts [Member] | Dec. 31, 2011 2013 Two-Way Collars [Member] | Dec. 31, 2011 2013 Three-Way Collars [Member] | Dec. 31, 2011 2013 Deferred Puts [Member] | Dec. 31, 2011 2014 Two-Way Collars [Member] | Dec. 31, 2011 2014 Three-Way Collars [Member]
Derivative Instruments [Line Items] |  |  |  |  |  |  |  |  |  |
Settlement Period |  |  | 2012 | 2012 | 2012 | 2013 | 2013 | 2013 | 2014 | 2014
Total Notional Amount of Oil (Barrels) |  |  | 1,756,718 | 2,906,500 | 641,000 | 807,500 | 1,887,000 | 93,000 | 62,000 | 155,000
Average Sub-Floor Price |  |  |  | 65.36 | 72.61 |  | 70.19 | 71.67 |  | 71.00
Average Floor Price |  |  | 85.49 | 89.97 | 92.61 | 89.23 | 90.84 | 91.67 | 90.00 | 91.00
Average Ceiling Price |  |  | 106.44 | 108.24 |  | 111.69 | 112.60 |  | 112.78 | 113.04
Average Deferred Premium |  |  |  |  | 6.10 |  |  | 6.33 |  |
Fair Value Asset (Liability) | $ 5,050 | $ 10,486 | $ (3,116) | $ (2,046) | $ (745) | $ 2,326 | $ (1,612) | $ (33) | $ 289 | $ (113)

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- Definition Aggregate notional amount of derivative expressed in nonmonetary units. For example, the number of barrels specified in a fuel oil forward purchase contract. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Article 12 + Details
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- Definition The average deferred premium related to commodity derivative contracts. + References No definition available. + Details
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- Definition The average strike price of the sold put that establishes the price at which if the market price falls below, the minimum price would be index price plus the difference between the purchased put (floor) and the sold put strike price. + References No definition available. + Details
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- Definition The average cap rate on a group of price risk derivatives such as caps or collars. A payment or receipt is triggered if the market rate exceeds the cap rate on the contract. + References No definition available. + Details
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- Definition Fair value as of the balance sheet date of the assets less the liabilities of a derivative or group of derivatives. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 15 -URI http://asc.fasb.org/extlink&oid=6947722&loc=d3e13495-108611 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 45 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=6945355&loc=d3e41228-113958 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 45 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=6945355&loc=d3e41271-113958 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 10 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=6947722&loc=d3e13433-108611 + Details
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