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Commitments and Contingencies (Contingencies) (Details) (USD $) In Millions, unless otherwise specified | 0 Months Ended | 1 Months Ended | 36 Months Ended | 0 Months Ended | 4 Months Ended |  | 0 Months Ended
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Apr. 20, 2009 Louisiana Department of Revenue Tax Litigation [Member] | Dec. 31, 2010 Louisiana Department of Revenue Tax Litigation [Member] lawsuit | Dec. 31, 2007 Louisiana Department of Revenue Tax Litigation [Member] | Dec. 09, 2010 Reed Litigation [Member] defendant plaintiff acre | Jul. 31, 2010 Reed Litigation [Member] plaintiff | Dec. 07, 2010 Reed Litigation [Member] defendant acre | Dec. 06, 2010 Reed Litigation [Member] acre | Jul. 31, 2010 Individual Counterparty [Member] Reed Litigation [Member] plaintiff | Jul. 31, 2010 Limited Liability Company [Member] Reed Litigation [Member] plaintiff
Loss Contingencies [Line Items] |  |  |  |  |  |  |  |  |
Alleged severance tax |  | $ 12.0 | $ 1.8 |  |  |  |  |  |
Lawsuits filed value | $ 2.3 | $ 4.4 |  |  |  |  |  |  |
Number of pending claims |  | 2 |  |  |  |  |  |  |
Number of defendants |  |  |  | 6 | 15 | 21 |  |  |
Number of plaintiffs |  |  |  | 4 |  |  |  | 6 | 1
Original number of acreage in litigation |  |  |  |  |  |  | 240 |  |
Amended number of acreage in litigation |  |  |  |  |  | 1,700 |  |  |

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- Definition Alleged severance tax underpayment by the Louisiana Department of Revenue due to fixed price contracts + References No definition available. + Details
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