Derivative Financial Instruments (Tables)

6 Months Ended

Jun. 30, 2012

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Schedule of fair value of derivatives in accompanying balance sheets

The following table details the fair value of derivatives recorded in the accompanying balance sheets, by category:

	As of June 30, 2012
	Derivative Assets			Derivative Liabilities
	Balance Sheet  Classification	Fair Value		Balance Sheet  Classification	Fair Value
	(in thousands)
Commodity Contracts	Current Assets	$	69,207	Current Liabilities	$	9,150
Commodity Contracts	Noncurrent Assets	44,270		Noncurrent Liabilities	956
Derivatives not designated as hedging instruments		$	113,477		$	10,106

	As of December 31, 2011
	Derivative Assets			Derivative Liabilities
	Balance Sheet  Classification	Fair Value		Balance Sheet  Classification	Fair Value
	(in thousands)
Commodity Contracts	Current Assets	$	55,813	Current Liabilities	$	42,806
Commodity Contracts	Noncurrent Assets	31,062		Noncurrent Liabilities	12,875
Derivatives not designated as hedging instruments		$	86,875		$	55,681

Schedule of unrealized and realized gains and losses on derivative instruments in the statement of operations

The following table summarizes the components of unrealized and realized derivative (gain) loss presented in the accompanying statements of operations:

	For the Three Months Ended June 30,						For the Six Months Ended June 30,
	2012			2011			2012			2011
	(in thousands)
Cash settlement (gain) loss:
Oil contracts	$	2,371		$	10,633		$	10,670		$	17,363
Gas contracts	(16,252		)	(590		)	(31,464		)	(2,317		)
NGL contracts	(2,565		)	3,933			(1,088		)	5,347
Total cash settlement (gain) loss	$	(16,446	)	$	13,976		$	(21,882	)	$	20,393
Unrealized (gain) loss on change in fair value:
Oil contracts	$	(92,774	)	$	(51,216	)	$	(63,283	)	$	16,151
Gas contracts	29,867			(6,681		)	12,233			(2,421		)
NGL contracts	(18,759		)	45			(22,964		)	10,430
Total net unrealized (gain) loss on change in fair value	$	(81,666	)	$	(57,852	)	$	(74,014	)	$	24,160
Total unrealized and realized derivative (gain) loss	$	(98,112	)	$	(43,876	)	$	(95,896	)	$	44,553

Detail of the effect of derivative instruments reclassified from AOCI to the statement of operations (net of income tax)

The following table summarizes the effect of derivative instruments on AOCIL and the accompanying statements of operations (net of income tax):

		Location in Consolidated Statements of Operations	For the Three Months Ended June 30,					For the Six Months Ended June 30,
	Derivatives		2012			2011		2012			2011
			(in thousands)
Amount reclassified from AOCIL	Commodity Contracts	Realized hedge gain (loss)	$	(116	)	$	3,951	$	(1,150	)	$	4,878