Property and Equipment (Details 1) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Breakdown of the Company's unproved and unevaluated property costs not subject to amortization
Costs incurred for Property acquisition	$ 139,962
Exploration wells	6,612
Amount for development wells	2,573
Capitalized interest	528
Total unproved and unevaluated	149,675	162,598
2012 [Member]
Breakdown of the Company's unproved and unevaluated property costs not subject to amortization
Costs incurred for Property acquisition	29,165
Exploration wells	4,680
Amount for development wells	2,573
Capitalized interest	70
Total unproved and unevaluated	36,488
2011 [Member]
Breakdown of the Company's unproved and unevaluated property costs not subject to amortization
Costs incurred for Property acquisition	21,748
Exploration wells	1,932
Capitalized interest	458
Total unproved and unevaluated	24,138
2010 [Member]
Breakdown of the Company's unproved and unevaluated property costs not subject to amortization
Costs incurred for Property acquisition	70,417
Total unproved and unevaluated	70,417
2009 and prior [member]
Breakdown of the Company's unproved and unevaluated property costs not subject to amortization
Costs incurred for Property acquisition	18,632
Total unproved and unevaluated	$ 18,632

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

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The capitalized costs incurred (excluded from amortization), as of the date of the balance sheet, in identifying areas that may warrant examination and in examining specific areas that are considered to have prospects of containing oil and gas reserves, including costs of drilling exploratory wells and exploratory-type stratigraphic test wells. Exploration costs may be incurred both before acquiring the related property (sometimes referred to in part as prospecting costs) and after acquiring the property. Principal types of exploration costs, which include depreciation and applicable operating costs of support equipment and facilities and other costs of exploration activities, are: costs of topographical, geographical and geophysical studies, rights of access to properties to conduct those studies, and salaries and other expenses of geologists, geophysical crews, and others conducting those studies. Collectively, these are sometimes referred to as geological and geophysical or "G&G" costs. Exploration costs also include costs of carrying and retaining undeveloped properties, such as delay rentals, ad valorem taxes on properties, legal costs for title defense, the maintenance of land and lease records, dry hole contributions and bottom hole contributions, costs of drilling and equipping exploratory wells and costs of drilling exploratory-type stratigraphic test wells.

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