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Supplemental Financial Information Exploration and Production (Details 5) (Details) (USD $) In Millions, unless otherwise specified | 12 Months Ended |
--- | --- | ---
Dec. 31, 2011 Mcfe | Dec. 31, 2010 Mcfe | Dec. 31, 2009 Mcfe | Dec. 31, 2008 Mcfe
Reserve Quantities [Line Items] |  |  |  |
Proved Developed Reserves, Net | 476,763,000 | 494,426,000 | 482,329,000 |
Proved Developed and Undeveloped Reserves, Extensions, Discoveries, and Additions | 65,049,000 | 56,523,000 | 42,297,000 |
Proved Developed and Undeveloped Reserves [Abstract] |  |  |  |
Proved Developed Reserves, Net | 476,763,000 | 494,426,000 | 482,329,000 |
Proved Undeveloped Reserves, Net | 109,145,000 | 151,170,000 | 171,395,000 |
Proved Developed and Undeveloped Reserves, Net | 585,908,000 | 645,596,000 | 653,724,000 | 810,371,000
Change in PUD reserve | (42,000,000) |  |  |
Amount of PUD reserves converted into proved developed reserves | 27,100,000 |  |  |
Drilling and completion capital | $ 62.9 |  |  |
Negative revision to PUD reserves | 53,600,000 |  |  |
New PUD reserves | 38,700,000 |  |  |
Future development costs estimated to be spent to develop PUD reserves year one | 109.3 |  |  |
Future development costs estimated to be spent to develop PUD reserves year two | 47.8 |  |  |
Future development costs estimated to be spent to develop PUD reserves year three | $ 13.7 |  |  |
Natural Gas Reserves [Member] |  |  |  |
Reserve Quantities [Line Items] |  |  |  |
Proved Developed Reserves, Net | 303,495 | 334,911 | 321,561 |
Proved Developed and Undeveloped Reserves, Extensions, Discoveries, and Additions | 28,221 | 36,191 | 26,882 |
Proved Developed and Undeveloped Reserves [Abstract] |  |  |  |
Proved Developed Reserves, Net | 303,495 | 334,911 | 321,561 |
Proved Undeveloped Reserves, Net | 76,332 | 113,486 | 126,864 |
Proved Developed and Undeveloped Reserves, Net | 379,827 | 448,397 | 448,425 | 604,282
Oil Reserves [Member] |  |  |  |
Reserve Quantities [Line Items] |  |  |  |
Proved Developed Reserves, Net | 28,878 | 26,586 | 26,794 |
Proved Developed and Undeveloped Reserves, Extensions, Discoveries, and Additions | 6,138 | 3,389 | 2,569 |
Proved Developed and Undeveloped Reserves [Abstract] |  |  |  |
Proved Developed Reserves, Net | 28,878 | 26,586 | 26,794 |
Proved Undeveloped Reserves, Net | 5,469 | 6,281 | 7,422 |
Proved Developed and Undeveloped Reserves, Net | 34,347 | 32,867 | 34,216 | 34,348

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- Definition Additions to proved reserves that result from (1) extension of the proved acreage of previously discovered (old) reservoirs through additional drilling in periods after discovery and (2) discovery of new fields with proved reserves or of new reservoirs of proved reserves in old fields. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 19 -Paragraph 59F -Subparagraph d -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 932 -SubTopic 235 -Section 50 -Paragraph 5 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=6821537&loc=d3e61831-109447 + Details
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- Definition The net quantity of proved reserves as of the balance sheet date. Proved oil reserves are the estimated quantities of crude oil and natural gas liquids which geological and engineering data demonstrate with reasonable certainty to be recoverable. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 932 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.4-10.(a)(2)) -URI http://asc.fasb.org/extlink&oid=6949603&loc=d3e511914-122862 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 19 -Paragraph 59F -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Article 4 -Section 10 -Paragraph a -Subparagraph 2 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 932 -SubTopic 235 -Section 50 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=6821537&loc=d3e61831-109447 + Details
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