Derivative Financial Instruments (Tables)

6 Months Ended

Jun. 30, 2012

Derivative Financial Instruments [Abstract]

Derivative financial instruments on the condensed consolidated balance sheets

Derivative Financial Instruments	Balance Sheet location	December 31, 2011			June 30, 2012
Commodity contracts	Current derivative financial instrument asset	$	42,803		$	34,234
Commodity contracts	Long-term derivative financial instrument asset		29,516			17,360
Commodity contracts	Current derivative financial instrument liability		(5,223	)		(5,424	)
Commodity contracts	Long-term derivative financial instrument liability		(4,611	)		(2,999	)
		$	62,485		$	43,171

Gains and losses associated with derivative financial instruments

	Three Months Ended June 30,						Six Months Ended June 30,
	2011			2012			2011			2012
Realized gains (losses)	$	6,671		$	18,618		$	15,907		$	30,703
Unrealized gains (losses)		(1,103	)		(18,777	)		(11,160	)		(18,837	)
Total	$	5,568		$	(159	)	$	4,747		$	11,866

Estimated volumes, fixed prices and fair values attributable to all of company oil and gas derivative contracts

	Remainder  of 2012			Year Ending December 31,								Total
				2013			2014		2015-2016
	($ in thousands, except per unit data)
Natural Gas Swaps
Contract volumes (Mmbtu)		5,524,592			9,000,003			—		1,047,000			15,571,595
Weighted-average fixed price per Mmbtu	$	5.71		$	7.28		$	—	$	4.00		$	6.51
Fair value, net	$	15,359		$	32,981		$	—	$	(458	)	$	47,882
Natural Gas Basis Swaps
Contract volumes (Mmbtu)		4,524,590			9,000,003			—		—			13,524,593
Weighted-average fixed price per Mmbtu	$	(0.72	)	$	(0.71	)	$	—	$	—		$	(0.71	)
Fair value, net	$	(2,356	)	$	(4,620	)	$	—	$	—		$	(6,976	)
Crude Oil Swaps
Contract volumes (Bbl)		33,342			65,892			61,680		112,056			272,970
Weighted-average fixed price per Bbl	$	93.86		$	101.70		$	97.00	$	92.29		$	95.82
Fair value, net	$	256		$	865		$	557	$	587		$	2,265
Total fair value, net	$	13,259		$	29,226		$	557	$	129		$	43,171

	Year Ending December 31,
	2012			2013			Total
	($ in thousands, except per unit data)
Natural Gas Swaps
Contract volumes (Mmbtu)		11,000,004			9,000,003			20,000,007
Weighted-average fixed price per Mmbtu	$	7.13		$	7.28		$	7.20
Fair value, net	$	42,803		$	29,516		$	72,319
Natural Gas Basis Swaps
Contract volumes (Mmbtu)		9,000,000			9,000,003			18,000,003
Weighted-average fixed price per Mmbtu	$	(0.70	)	$	(0.71	)	$	(0.71	)
Fair value, net	$	(4,767	)	$	(4,611	)	$	(9,378	)
Crude Oil Swaps
Contract volumes (Bbl)		42,000			—			42,000
Weighted-average fixed price per Bbl	$	87.90		$	—		$	87.90
Fair value, net	$	(456	)	$	—		$	(456	)
Total fair value, net	$	37,580		$	24,905		$	62,485