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Acquisition and Development Agreement and Carry and Earning Agreement (Details) (USD $) |  |  | 12 Months Ended |
--- | --- | --- | --- | ---
Dec. 31, 2013 | Dec. 31, 2012 | Dec. 31, 2013 Mitsui E&P Texas LP | Jun. 30, 2011 Mitsui E&P Texas LP
Acquisition and Development Agreement [Abstract] |  |  |  |
Percentage of working interests transferred to acquiree entity (as a percent) |  |  |  | 12.50%
Acreage of working interests transferred to acquiree entity (in acres) |  |  |  | 39,000
Percentage of the entity's costs and expenses during the first three years following the closing of the transaction, borne by the acquiree entity (as a percent) |  |  | 90.00% |
Costs and expenses incurred by acquiree entity on behalf of entity that the acquiree entity has agreed to pay |  |  |  | $ 680,000,000
Portion of Drilling and Completion Costs Not Carried by Acquirer |  |  | 10.00% |
Restricted cash | 96,713,000 | 86,773,000 | 94,959,000 |
Carry Amount, Portion Used to Date |  |  | $ 573,800,000 |

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- Definition Represents the acreage of working interests transferred to acquiree entity. + References No definition available. + Details
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- Definition Cash and equivalents whose use in whole or in part is restricted for the long-term, generally by contractual agreements or regulatory requirements. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.1) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 1 -Article 5 + Details
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