v2.4.0.6

Summary of Significant Accounting Policies - Summary of Oil and Gas Properties (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Mineral interests in properties:
Unproved leasehold costs	$ 49,148	$ 46,813
Proved leasehold costs	32,252	26,845
Wells and related equipment and facilities	908,456	626,564
Support equipment	6,753	5,135
Uncompleted wells, equipment and facilities	28,831	27,302
Total costs	1,025,440	732,659
Less accumulated depreciation, depletion and amortization	(197,751)	(137,980)
Net capitalized costs	$ 827,689	$ 594,679

X

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Amount of accumulated depreciation, depletion, amortization and valuation allowance relating to oil and gas producing activities.

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The sum of capitalized costs relating to oil and gas producing activities before accounting for accumulated depreciation.

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Net amount of capitalized costs relating to oil and gas producing activities.

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Capitalized costs of proved properties incurred for any combination mineral interests acquisitions; wells and related equipment; support equipment and facilities; and uncompleted wells and equipment and other costs not previously disclosed within this table.

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