Oil and Gas Operations (Unaudited) (Tables)

12 Months Ended

Dec. 31, 2011

Oil and Gas Exploration and Production Industries Disclosures [Abstract]

Schedule of capitalized costs

The following table sets forth capitalized costs:

(in thousands)	December 31, 2011		December 31, 2010
Proved	$	4,927,576	$	3,868,945
Unproved	238,792		211,834
Total capitalized costs	5,166,368		4,080,779
Accumulated depreciation, depletion and amortization	1,382,526		1,161,635
Capitalized costs, net	$	3,783,842	$	2,919,144

Schedule of cost incurred in property acquisition, exploration and development activities

The following table sets forth costs incurred in property acquisition, exploration and development activities and includes both capitalized costs and costs charged to expense during the year:

Years ended December 31, (in thousands)	2011		2010		2009
Property acquisition:
Proved	$	214,993	$	207,161	$	186,263
Unproved	91,888		201,881		5,100
Exploration	190,854		37,371		16,590
Development	623,775		332,541		226,841
Total costs incurred	$	1,121,510	$	778,954	$	434,794

Schedule of results of operations from producing activities

The following table sets forth results of the Company's oil and gas operations from producing activities:

Years ended December 31, (in thousands)	2011			2010		2009
Gross revenues	$	944,908	*	$	957,371	$	815,465
Production (lifting costs)	257,045			224,901		217,429
Exploration expense	13,110			64,584		10,234
Depreciation, depletion and amortization	240,232			200,179		180,752
Accretion expense	6,837			6,178		4,935
Income tax expense	154,180			166,750		143,691
Results of operations from producing activities	$	273,504		$	294,779	$	258,424

*The year ended December 31, 2011 gross revenues includes a pre-tax non-cash mark-to-market loss on derivatives of $37.6 million.

Schedule of proved developed and undeveloped oil and gas reserves

The independent reservoir engineers have issued reports covering approximately 99 percent of the Company's ending proved reserves indicating that in their judgment the estimates are reasonable in the aggregate.

Year ended December 31, 2011	Gas MMcf		Oil MBbl		NGL MBbl		Total MMBOE
Proved reserves at beginning of period	954,387		103,262		40,601		302.9
Revisions of previous estimates	(12,823	)	(4,513	)	841		(5.8	)
Purchases	19,362		12,583		5,055		20.8
Extensions and discoveries	68,160		24,564		9,637		45.6
Production	(71,718	)	(6,318	)	(2,177	)	(20.4	)
Proved reserves at end of period	957,368		129,578		53,957		343.1
Proved developed reserves at end of period	788,812		83,899		33,154		248.5
Proved undeveloped reserves at end of period	168,556		45,679		20,803		94.6

Year ended December 31, 2010	Gas MMcf		Oil MBbl		NGL MBbl		Total MMBOE
Proved reserves at beginning of period	897,546		77,963		30,257		257.8
Revisions of previous estimates	66,679		(2,243	)	2,434		11.3
Purchases	21,700		16,443		5,730		25.8
Extensions and discoveries	39,570		16,234		4,058		26.8
Production	(70,924	)	(5,131	)	(1,880	)	(18.8	)
Sales	(184	)	(4	)	2		—
Proved reserves at end of period	954,387		103,262		40,601		302.9
Proved developed reserves at end of period	786,292		72,030		28,809		231.9
Proved undeveloped reserves at end of period	168,095		31,232		11,792		71.0

Year ended December 31, 2009	Gas MMcf		Oil MBbl		NGL MBbl		Total MMBOE
Proved reserves at beginning of period	1,038,453		62,034		28,953		264.1
Revisions of previous estimates	(122,862	)	1,175		(1,411	)	(20.7	)
Purchases	9,646		12,064		2,537		16.2
Extensions and discoveries	45,791		8,144		1,969		17.7
Production	(72,337	)	(4,690	)	(1,791	)	(18.5	)
Sales	(1,145	)	(764	)	—		(1.0	)
Proved reserves at end of period	897,546		77,963		30,257		257.8
Proved developed reserves at end of period	743,859		66,078		24,985		215.0
Proved undeveloped reserves at end of period	153,687		11,885		5,272		42.8

Schedule of standardized measure of discounted future net cash flows relating to proved oil and gas reserves

Years ended December 31, (in thousands)	2011		2010		2009
Future gross revenues	$	18,196,229	$	13,210,211	$	8,208,613
Future production costs	5,823,395		4,959,403		3,915,736
Future development costs	1,539,072		1,026,903		533,674
Future income tax expense	3,326,382		2,201,742		944,875
Future net cash flows	7,507,380		5,022,163		2,814,328
Discount at 10% per annum	3,878,217		2,555,027		1,251,138
Standardized measure of discounted future net cash flows relating to proved oil and gas reserves	$	3,629,163	$	2,467,136	$	1,563,190
Discounted future net cash flows before income taxes	$	4,691,086	$	3,155,746	$	1,765,632

Schedule of principal sources of changes in standardized measure of discounted future net cash flows

The following are the principal sources of changes in the standardized measure of discounted future net cash flows:

Years ended December 31, (in thousands)	2011			2010			2009
Balance at beginning of year	$	2,467,136		$	1,563,190		$	1,626,617
Revisions to reserves proved in prior years:
Net changes in prices, production costs and future development costs	707,411			945,179			(248,236		)
Net changes due to revisions in quantity estimates	(80,004		)	36,349			(117,990		)
Development costs incurred, previously estimated	392,720			195,269			140,169
Accretion of discount	246,714			156,319			162,662
Changes in timing and other	(25,937		)	15,815			97,142
Total revisions	1,240,904			1,348,931			33,747
New field discoveries and extensions, net of future production and development costs	755,977			319,223			81,954
Sales of oil and gas produced, net of production costs	(763,171		)	(576,755		)	(389,125		)
Purchases	232,768			278,384			116,435
Sales	—			87			(7,571		)
Net change in income taxes	(304,451		)	(465,924		)	101,133
Net change in standardized measure of discounted future net cash flows	1,162,027			903,946			(63,427		)
Balance at end of year	$	3,629,163		$	2,467,136		$	1,563,190