Supplemental Oil And Gas Reserve Information - Unaudited (Tables)

12 Months Ended

Dec. 31, 2011

Supplemental Oil And Gas Reserve Information - Unaudited [Abstract]

Net Proved, Proved Developed And Proved Undeveloped Reserves

		September 30,			September 30,			September 30,
	Oil (MBbl)			Gas (MMcf)			MBoe
2009
Proved reserves
Beginning balance		2,193			671			2,304
Revisions of previous estimates		781			(84	)		767
Extensions, discoveries and other additions		8,381			3,414			8,950
Sales of reserves in place		(2	)		(16	)		(5	)
Purchases of reserves in place		1,726			1,611			1,995
Production		(658	)		(326	)		(712	)
Net proved reserves at December 31, 2009		12,421			5,270			13,299
Proved developed reserves, December 31, 2009		5,231			2,293			5,613
Proved undeveloped reserves, December 31, 2009		7,190			2,977			7,686
2010
Proved reserves
Beginning balance		12,421			5, 270			13,299
Revisions of previous estimates		2,235			1,897			2,552
Extensions, discoveries and other additions		22,445			12,172			24,473
Sales of reserves in place		(122	)		(5	)		(123	)
Purchases of reserves in place		1,363			696			1,479
Production		(1,792	)		(651	)		(1,900	)
Net proved reserves at December 31, 2010		36,550			19,379			39,780
Proved developed reserves, December 31, 2010		15,650			8,208			17,018
Proved undeveloped reserves, December 31, 2010		20,900			11,171			22,762
2011
Proved reserves
Beginning balance		36,550			19,379			39,780
Revisions of previous estimates		(262	)		(159	)		(288	)
Extensions, discoveries and other additions		36,464			40,220			43,168
Sales of reserves in place		(56	)		(518	)		(142	)
Purchases of reserves in place		100			65			111
Production		(3,732	)		(1,087	)		(3,914	)
Net proved reserves at December 31, 2011		69,064			57,900			78,715
Proved developed reserves, December 31, 2011		31,749			24,535			35,839
Proved undeveloped reserves, December 31, 2011		37,315			33,365			42,876

Standardized Measure of Discounted Future Cash Flows

		September 30,			September 30,			September 30,
	At Year Ended December 31,
	2011			2010			2009
	(In thousands)
Future cash inflows	$	6,508,604		$	2,620,530		$	664,480
Future production costs		(1,690,264	)		(696,890	)		(258,137	)
Future development costs		(783,486	)		(362,328	)		(120,212	)
Future income tax expense(1)		(1,225,395	)		(495,788	)		—
Future net cash flows		2,809,459			1,065,524			286,131
10% annual discount for estimated timing of cash flows		(1,489,988	)		(579,789	)		(152,601	)
Standardized measure of discounted future net cash flows	$	1,319,471		$	485,735		$	133,530

(1) Does not include the effect of income taxes on discounted future net cash flows for the years ended December 31, 2009 because as of December 31, 2009, the Company was a limited liability company not subject to entity-level taxation. Accordingly, no provision for federal or state corporate income taxes was provided because taxable income was passed through to the Company's equity holders.

Changes In The Standardized Measure Of Discounted Future Net Cash Flows Applicable To Proved Oil And Natural Gas Reserves

		September 30,			September 30,			September 30,
	2011			2010			2009
	(In thousands)
January 1,	$	485,735		$	133,530		$	17,730
Net changes in prices and production costs		299,108			126,089			11,423
Net changes in future development costs		(38,244	)		(9,767	)		1,998
Sales of oil and natural gas, net		(262,485	)		(100,577	)		(25,254	)
Extensions		989,697			426,824			71,333
Discoveries		—			—			—
Purchases of reserves in place		2,679			26,919			36,809
Sales of reserves in place		(2,499	)		(1,720	)		(108	)
Revisions of previous quantity estimates		(5,058	)		55,149			7,700
Previously estimated development costs incurred		146,847			32,729			—
Accretion of discount		69,782			13,353			3,352
Net change in income taxes		(372,146	)		(212,085	)		—
Changes in timing and other		6,055			(4,709	)		8,547
December 31,	$	1,319,471		$	485,735		$	133,530