Annual report pursuant to Section 13 and 15(d)

Supplemental Oil And Gas Disclosures (Schedule Of Oil And Natural Gas Information) (Details)

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Supplemental Oil And Gas Disclosures (Schedule Of Oil And Natural Gas Information) (Details)
 3 Months Ended 12 Months Ended
Dec. 31, 2009
Dec. 31, 2011
Dec. 31, 2010
Dec. 31, 2009
Reserve Quantities [Line Items]        
Proved reserves changes for accounting changes, Bcfe       23.2
Reserve changes for performance, Bcfe       4.7
Number of non-core oil and natural gas fields sold 36      
Revisions due to price (in Bcfe)   6.3 17.5  
Revisions due to NGL marketing arrangement (in Bcfe)   16.5    
Revisions related to compressor project (in Bcfe)   11.3    
Revisions due to additional wells brought to production (in Bcfe)   10.6    
Discoveries [Member]
        
Reserve Quantities [Line Items]        
Changes due to extensions and discoveries, Bcfe     21.9  
Extensions [Member]
        
Reserve Quantities [Line Items]        
Changes due to extensions and discoveries, Bcfe     7.2  
Main Pass [Member] | Discoveries [Member]
        
Reserve Quantities [Line Items]        
Changes due to extensions and discoveries, Bcfe   13.9    
South Timbalier [Member] | Discoveries [Member]
        
Reserve Quantities [Line Items]        
Changes due to extensions and discoveries, Bcfe   8.0    
Ship Shoal [Member] | Discoveries [Member]
        
Reserve Quantities [Line Items]        
Changes due to extensions and discoveries, Bcfe   3.7    
MMBbls [Member] | Oil [Member]
        
Reserve Quantities [Line Items]        
Proved reserves, beginning balance   34.0 [1] 31.2 [1] 40.0 [1]
Revisions of previous estimates   0.8 [1],[2] (0.2) [1],[3] (2.1) [1],[4]
Extensions and discoveries   2.0 [1],[5] 1.2 [1],[6] 1.2 [1],[7]
Purchase of minerals in place   20.7 [1],[8] 7.7 [1],[9]  
Sales of reserves       (1.8) [1],[10]
Production   (6.1) [1] (5.9) [1] (6.1) [1]
Proved reserves, ending balance 31.2 [1] 51.4 [1] 34.0 [1] 31.2 [1]
MMBbls [Member] | Natural Gas Liquids [Member]
        
Reserve Quantities [Line Items]        
Proved reserves, beginning balance   4.2 [1] 3.0 [1] 3.9 [1]
Revisions of previous estimates   5.5 [1],[2] 1.2 [1],[3]  
Extensions and discoveries   0.4 [1],[5] 0.5 [1],[6] 0.3 [1],[7]
Purchase of minerals in place   8.9 [1],[8] 0.7 [1],[9]  
Sales of reserves       (0.1) [1],[10]
Production   (1.9) [1] (1.2) [1] (1.1) [1]
Proved reserves, ending balance 3.0 [1] 17.1 [1] 4.2 [1] 3.0 [1]
MMBbls [Member] | Proved Developed Reserves [Member] | Oil [Member]
        
Reserve Quantities [Line Items]        
Proved reserves, ending balance 21.3 [1] 23.4 [1] 23.6 [1] 21.3 [1]
MMBbls [Member] | Proved Developed Reserves [Member] | Natural Gas Liquids [Member]
        
Reserve Quantities [Line Items]        
Proved reserves, ending balance 2.4 [1] 11.0 [1] 3.4 [1] 2.4 [1]
MMBbls [Member] | Proved Undeveloped Reserves [Member] | Oil [Member]
        
Reserve Quantities [Line Items]        
Proved reserves, ending balance 9.9 [1] 28.0 [1] 10.4 [1] 9.9 [1]
MMBbls [Member] | Proved Undeveloped Reserves [Member] | Natural Gas Liquids [Member]
        
Reserve Quantities [Line Items]        
Proved reserves, ending balance 0.6 [1] 6.1 [1] 0.8 [1] 0.6 [1]
Bcf [Member] | Natural Gas [Member]
        
Reserve Quantities [Line Items]        
Proved reserves, beginning balance   256.3 [1] 165.8 [1] 227.9 [1]
Revisions of previous estimates   13.5 [1],[2] 14.6 [1],[3] (13.0) [1],[4]
Extensions and discoveries   17.7 [1],[5] 19.1 [1],[6] 14.5 [1],[7]
Purchase of minerals in place   55.9 [1],[8] 101.5 [1],[9] 0.4 [1]
Sales of reserves       (12.4) [1],[10]
Production   (53.7) [1] (44.7) [1] (51.6) [1]
Proved reserves, ending balance 165.8 [1] 289.7 [1] 256.3 [1] 165.8 [1]
Bcf [Member] | Proved Developed Reserves [Member] | Natural Gas [Member]
        
Reserve Quantities [Line Items]        
Proved reserves, ending balance 141.3 [1] 251.4 [1] 229.1 [1] 141.3 [1]
Bcf [Member] | Proved Undeveloped Reserves [Member] | Natural Gas [Member]
        
Reserve Quantities [Line Items]        
Proved reserves, ending balance 24.5 [1] 38.3 [1] 27.2 [1] 24.5 [1]
MMBoe [Member] | Barrel Equivalent [Member]
        
Reserve Quantities [Line Items]        
Proved reserves, beginning balance   80.9 [11] 61.8 [11] 81.9 [11]
Revisions of previous estimates   8.6 [11],[2] 3.4 [11],[3] (4.3) [11],[4]
Extensions and discoveries   5.3 [11],[5] 4.9 [11],[6] 3.9 [11],[7]
Purchase of minerals in place   39.0 [11],[8] 25.3 [11],[9] 0.1 [11]
Sales of reserves       (4.0) [10],[11]
Production   (16.9) [11] (14.5) [11] (15.8) [11]
Proved reserves, ending balance 61.8 [11] 116.9 [11] 80.9 [11] 61.8 [11]
MMBoe [Member] | Proved Developed Reserves [Member] | Barrel Equivalent [Member]
        
Reserve Quantities [Line Items]        
Proved reserves, ending balance 47.3 [11] 76.4 [11] 65.2 [11] 47.3 [11]
MMBoe [Member] | Proved Undeveloped Reserves [Member] | Barrel Equivalent [Member]
        
Reserve Quantities [Line Items]        
Proved reserves, ending balance 14.5 [11] 40.5 [11] 15.7 [11] 14.5 [11]
Bcfe [Member] | Natural Gas Equivalent [Member]
        
Reserve Quantities [Line Items]        
Proved reserves, beginning balance   485.4 [11] 371.0 [11] 491.1 [11]
Revisions of previous estimates   51.1 [11],[2] 20.2 [11],[3] (25.4) [11],[4]
Extensions and discoveries   32.0 [11],[5] 29.2 [11],[6] 23.4 [11],[7]
Purchase of minerals in place   234.1 [11],[8] 152.0 [11],[9] 0.7 [11]
Sales of reserves       (24.0) [10],[11]
Production   (101.5) [11] (87.0) [11] (94.8) [11]
Proved reserves, ending balance 371.0 [11] 701.1 [11] 485.4 [11] 371.0 [11]
Bcfe [Member] | Proved Developed Reserves [Member] | Natural Gas Equivalent [Member]
        
Reserve Quantities [Line Items]        
Proved reserves, ending balance 283.5 [11] 458.2 [11] 391.3 [11] 283.5 [11]
Bcfe [Member] | Proved Undeveloped Reserves [Member] | Natural Gas Equivalent [Member]
        
Reserve Quantities [Line Items]        
Proved reserves, ending balance 87.5 [11] 242.9 [11] 94.1 [11] 87.5 [11]
[1] Estimated reserves as of December 31, 2011, 2010 and 2009 are based on the unweighted average of first-day-of-the-month commodity prices over the period January through December for those years in accordance with current definitions and guidelines set forth by the SEC and the FASB. Estimated of reserves as of December 31, 2008 were based on end-of-year prices.
[2] Includes revision of 6.3 Bcfe due to an increase in average prices, 16.5 Bcfe for a change in NGLs marketing arrangements that allow us to recover a greater percentage of our NGLs from the gas stream, 11.3 Bcfe increase due to additional compression at our Tahoe field that allows us to reduce the drawdown pressure that increases production and ultimate recoveries, and 10.6 Bcfe at Fairway for revisions to reserve estimates from the acquisition date to year end.
[3] Includes revisions due to price of 17.5 Bcfe.
[4] Revisions for 2009 included decreases attributable to revised reserve reporting requirements for oil and natural gas companies enacted by the SEC and the FASB, which became effective for annual reporting periods ending on or after December 31, 2009. The initial application of these rules resulted in the removal of 23.2 Bcfe of proved undeveloped reserves associated with two of our fields for which our plan of development was not within five years from when the reserves were initially recorded, as required. Also included in the revisions of previous estimates for 2009 are negative revisions of 4.7 Bcfe due to performance.
[5] Includes discoveries of 13.9 Bcfe at Main Pass 98 and 8.0 Bcfe at Ship Shoal 349/359 and extensions of 3.7 Bcfe at Main Pass 108.
[6] Includes discoveries of 21.9 Bcfe primarily in the Main Pass 108, Main Pass 98 and Main Pass 283 fields and extensions of 7.2 Bcfe primarily in the Main Pass 283 field.
[7] The majority of these volumes are attributable to extensions and discoveries resulting from our participation in the drilling of eight successful exploratory wells in 2009, all of which were on the conventional shelf.
[8] Primarily due to the properties acquired from Opal (the Yellow Rose Properties) and the properties acquired from Shell (the Fairway Properties).
[9] Primarily due to the properties acquired from Total (Matterhorn and Virgo fields) and the properties acquired from Shell (Tahoe, Southeast Tahoe and Droshky fields).
[10] In the second quarter of 2009, we sold one of our fields in Louisiana state waters, and in the fourth quarter of 2009, we sold 36 non-core oil and natural gas fields in the Gulf of Mexico, subject to the terms of the purchase and sale agreements.
[11] Bcfe and MMBoe are determined using the ratio of six thousand cubic feet ("Mcf") of natural gas to one barrel ("Bbl") of crude oil, condensate or NGLs (totals may not compute due to rounding). The conversion ratio does not assume price equivalency, and the price per Mcfe for oil and NGLs may differ significantly from the price per Mcf for natural gas. Similarly, the price per Bbl for oil for may differ significantly from the price per Bbl for NGLs.