Derivative Financial Instruments (Tables)

9 Months Ended

Sep. 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 September 30, 2012
	Derivative Assets			Derivative Liabilities
	Balance Sheet  Classification	Fair Value		Balance Sheet  Classification	Fair Value
	(in thousands)
Commodity Contracts	Current Assets	$	41,865	Current Liabilities	$	19,352
Commodity Contracts	Noncurrent Assets	22,383		Noncurrent Liabilities	8,802
Derivatives not designated as hedging instruments		$	64,248		$	28,154

	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 September 30,						For the Nine Months Ended September 30,
	2012			2011			2012			2011
	(in thousands)
Cash settlement (gain) loss:
Oil contracts	$	2,472		$	1,058		$	13,142		$	18,421
Gas contracts	(9,031		)	(1,434		)	(40,495		)	(3,751		)
NGL contracts	(4,362		)	4,131			(5,450		)	9,478
Total cash settlement (gain) loss	$	(10,921	)	$	3,755		$	(32,803	)	$	24,148
Unrealized (gain) loss on change in fair value:
Oil contracts	$	30,667		$	(106,780	)	$	(32,616	)	$	(90,629	)
Gas contracts	28,231			(19,083		)	40,464			(21,504		)
NGL contracts	7,879			(6,317		)	(15,085		)	4,113
Total net unrealized (gain) loss on change in fair value	$	66,777		$	(132,180	)	$	(7,237	)	$	(108,020	)
Total unrealized and realized derivative (gain) loss	$	55,856		$	(128,425	)	$	(40,040	)	$	(83,872	)

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 Statements of Operations	For the Three Months Ended September 30,					For the Nine Months Ended September 30,
	Derivatives		2012			2011		2012			2011
			(in thousands)
Amount reclassified from AOCIL	Commodity Contracts	Realized hedge gain (loss)	$	(315	)	$	4,271	$	(1,465	)	$	9,149