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Contingencies (Details) (USD $) |  | 12 Months Ended |  | 0 Months Ended | 36 Months Ended |  | 1 Months Ended | 0 Months Ended | 4 Months Ended |  | 0 Months Ended
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Dec. 31, 2012 | Dec. 31, 2012 Shell Trading Company [Member] Oil [Member] | Dec. 31, 2011 Shell Trading Company [Member] Oil [Member] | Dec. 31, 2010 Shell Trading Company [Member] Oil [Member] | Dec. 31, 2012 Diamondback [Member] Oil [Member] | Dec. 31, 2011 Diamondback [Member] Oil [Member] | Dec. 31, 2010 Diamondback [Member] Oil [Member] | Dec. 31, 2012 Diamondback [Member] Natural Gas Liquids [Member] | Dec. 31, 2011 Diamondback [Member] Natural Gas Liquids [Member] | Dec. 31, 2011 Diamondback [Member] Natural Gas [Member] | Dec. 31, 2010 Diamondback [Member] Natural Gas [Member] | Dec. 31, 2012 North American Gas [Member] Natural Gas [Member] | Dec. 31, 2012 Hess [Member] Natural Gas [Member] | Dec. 31, 2012 Chevron [Member] Natural Gas [Member] | Dec. 31, 2011 Chevron [Member] Natural Gas [Member] | Dec. 31, 2010 Chevron [Member] Natural Gas [Member] | Dec. 31, 2011 Hilcorp Energy Company [Member] Natural Gas [Member] | Dec. 31, 2010 Hilcorp Energy Company [Member] Natural Gas [Member] | Dec. 31, 2012 Maximum [Member] | Apr. 20, 2009 Louisiana Department of Revenue Tax Litigation [Member] | Dec. 31, 2007 Louisiana Department of Revenue Tax Litigation [Member] | Dec. 31, 2010 Louisiana Department of Revenue Tax Litigation [Member] lawsuit | Nov. 30, 2006 Cudd Pressure Control Litigation [Member] defendant | Nov. 03, 2008 Cudd Pressure Control Litigation [Member] Royalty Fee [Member] | Nov. 03, 2008 Cudd Pressure Control Litigation [Member] Minimum [Member] Attorney Fees [Member] | Dec. 09, 2010 Reed Litigation [Member] plaintiff defendant acre | Jul. 31, 2010 Reed Litigation [Member] defendant | Dec. 07, 2010 Reed Litigation [Member] defendant acre | Dec. 06, 2010 Reed Litigation [Member] acre | Jul. 31, 2010 Reed Litigation [Member] Individual Counterparty [Member] plaintiff | Jul. 31, 2010 Reed Litigation [Member] Limited Liability Company [Member] plaintiff
Loss Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Alleged severance tax |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 1,800,000 |  |  |  |  |  |  |  |  |  |
Lawsuits filed value |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 2,275,729 |  |  |  | 11,800,000 | 450,000 |  |  |  |  |  |
Number of pending claims |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 2 |  |  |  |  |  |  |  |  |
Number of defendants |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 6 |  |  | 6 | 15 | 21 |  |  |
Damages sought as a percentage of final judgement |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 10.00% |  |  |  |  |  |
Number of plaintiffs |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 4 |  |  |  | 6 | 1
Original number of acreage in litigation |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 240 |  |
Amended number of acreage in litigation |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1,700 |  |  |
FDIC insured amount |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 250,000 |  |  |  |  |  |  |  |  |  |  |  |
Uninsured cash amount | $ 166,588,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage of production sold |  | 92.00% | 93.00% | 75.00% | 8.00% | 7.00% | 19.00% | 91.00% | 100.00% | 22.00% | 50.00% | 41.00% | 18.00% | 16.00% | 27.00% | 32.00% | 50.00% | 10.00% |  |  |  |  |  |  |  |  |  |  |  |  |

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