Oil And Natural Gas Properties And Gas Gathering Assets (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended	9 Months Ended
Sep. 30, 2011	Sep. 30, 2011	Sep. 30, 2010	Dec. 31, 2010
Oil And Natural Gas Properties And Gas Gathering Assets [Abstract]
Cost for unproved properties	$ 747,131	$ 747,131		$ 599,409
Minimum evaluation period for oil and natural gas cost		1
Maximum evaluation period for oil and natural gas cost		7
Full cost ceiling limitation, discount rate		10.00%
Reference price for oil (per Bbl)		94.50
Reference price for natural gas (per Mmbtu)		4.16
Impairment loss on long-lived asset	$ 6,800	$ 6,800	$ 0

Capitalized costs of unproved properties incurred for any combination mineral interests acquisitions and other costs not previously disclosed within this table.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Unproved Properties

-URI http://asc.fasb.org/extlink&oid=6527831

-Topic 932

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 19

-Paragraph 59M

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 FASB

-Name Accounting Standards Codification

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-URI http://asc.fasb.org/extlink&oid=6808249

Reference 4: http://www.xbrl.org/2003/role/presentationRef

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The aggregate amount of write-downs for impairments recognized during the period for long-lived assets held for abandonment, exchange or sale.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 144

-Paragraph 27, 28, 29, 30

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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

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Full Cost Ceiling Limitation, Discount Rate

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Maximum evaluation period for unproved oil and natural gas costs

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Minimum evaluation period for unproved oil and natural gas costs

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Natural Gas price used in the full cost ceiling test. This price is an average of the prices for the first-day-of-the-month during the previous 12 months.

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Oil And Natural Gas Properties And Gas Gathering Assets [Abstract]

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Oil price used in the full cost ceiling test. This price is an average of the prices for the first-day-of-the-month during the previous 12 months.

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