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Supplemental Oil and Gas Disclosures - Results of Operations for Oil and Natural Gas Producing Activities (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Supplemental Oil and Gas Disclosures [Abstract]
Revenues	$ 1,084,412	$ 670,491	$ 330,422
Production costs	221,095	127,146	67,937
Depreciation, depletion and amortization	298,999	202,398	74,101
Exploration costs	2,260	3,250	1,685
Impairment of oil and gas properties	1,168	3,581	3,610
Loss on sale of properties	0	0	207
Income tax expense	196,312	116,941	64,009
Results of operations for oil and natural gas producing activities	$ 364,578	$ 217,175	$ 118,873

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Amount of gain (loss) on sale or disposal of oil and gas property or timber property.

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Depreciation, depletion and amortization, and valuation provisions (impairments) related to oil and gas producing activities.

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Exploration costs from oil and gas producing activities.

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Costs related to the impairment of oil and gas properties.

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Income tax expense for oil and gas producing activities.

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The results of operations for oil and gas producing activities, excluding corporate overhead and interest costs.

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Production (lifting) costs from oil and gas producing activities, including but not limited to lease operating expense, production and ad valorem taxes, and transportation expense.

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Total revenues from oil and gas producing activities.

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