Derivative Financial Instruments (Tables)

3 Months Ended

Mar. 31, 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 March 31, 2012
	Derivative Assets			Derivative Liabilities
	Balance Sheet  Classification	Fair Value		Balance Sheet  Classification	Fair Value
	(in thousands)
Commodity Contracts	Current Assets	$	67,457	Current Liabilities	$	50,764
Commodity Contracts	Noncurrent Assets	30,595		Noncurrent Liabilities	25,397
Derivatives not designated as hedging instruments		$	98,052		$	76,161

	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 loss presented in the accompanying statements of operations:

	For the Three Months Ended March 31,
	2012			2011
	(in thousands)
Cash settlement (gain) loss:
Oil contracts	$	8,299		$	6,730
Gas contracts	(15,212		)	(1,727		)
NGL contracts	1,477			1,414
Total cash settlement (gain) loss	$	(5,436	)	$	6,417
Unrealized (gain) loss on change in fair value:
Oil contracts	$	29,491		$	67,367
Gas contracts	(17,634		)	4,260
NGL contracts	(4,205		)	10,385
Total net unrealized loss on change in fair value	$	7,652		$	82,012
Total unrealized and realized derivative loss	$	2,216		$	88,429

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 March 31,
	Derivatives		2012			2011
			(in thousands)
Amount reclassified from AOCIL to realized hedge gain (loss)	Commodity Contracts	Realized hedge gain (loss)	$	(1,034	)	$	927