Derivative Instruments and Hedging Activities (Tables)

12 Months Ended

Dec. 31, 2011

Derivative Instruments and Hedging Activities [Abstract]

Location and fair value amounts of derivative instruments reported in balance sheet

Fair Value of Derivative Instruments at December 31, 2011
	Asset Derivatives			Liability Derivatives
Description	Balance Sheet Location	Fair Value		Balance Sheet Location	Fair Value
Commodity contracts	Current assets: Fair value of hedging contracts	$	25,177	Current liabilities: Fair value of hedging contracts	($	11,122	)
	Long-term assets: Fair value of hedging contracts		22,543	Long-term liabilities: Fair value of hedging contracts		(815	)
		$	47,720		($	11,937	)

Fair Value of Derivative Instruments at December 31, 2010
	Asset Derivatives			Liability Derivatives
Description	Balance Sheet Location	Fair Value		Balance Sheet Location	Fair Value
Commodity contracts	Current assets: Fair value of hedging contracts	$	12,955	Current liabilities: Fair value of hedging contracts	($	32,144	)
	Long-term assets: Fair value of hedging contracts		—	Long-term liabilities: Fair value of hedging contracts		(3,606	)
		$	12,955		($	35,750	)

Effect of Derivative Instruments in the statement of operations

The Effect of Derivative Instruments on the Statement of Operations for the Years Ended December 31, 2011, 2010 and 2009
Derivatives in Cash Flow Hedging Relationships	Amount of Gain (Loss) Recognized in OCI on Derivative (a)			Gain (Loss) Reclassified from Accumulated OCI into Income (Effective Portion) (b)				Gain Recognized in Income on Derivative (Ineffective Portion)
				Location				Location
	2011				2011				2011
Commodity contracts	$	36,072		Operating revenue - oil/gas production	($	13,274	)	Derivative income, net	$	1,418
Total	$	36,072			($	13,274	)		$	1,418
	2010				2010				2010
Commodity contracts	$	1,176		Operating revenue - oil/gas production	$	9,631		Derivative income, net	$	3,265
Total	$	1,176			$	9,631			$	3,265
	2009				2009				2009
Commodity contracts	($	100,292	)	Operating revenue - oil/gas production	$	163,176		Derivative income, net	$	3,061
Total	($	100,292	)		$	163,176			$	3,061

(a) Net of related tax effect.

(b) For the year ended December 31, 2011, effective hedging contracts decreased oil revenue by $32,706 and increased gas revenue by $19,432. For the year ended December 31, 2010, effective hedging contracts decreased oil revenue by $29,047 and increased gas revenue by $38,678. For the year ended December 31, 2009, effective hedging contracts increased oil revenue by $61,747 and increased gas revenue by $101,429.

Hedging Positions

	Fixed-Price Swaps NYMEX (except where noted)
	Natural Gas				Oil
	Daily Volume (MMBtus/d)		Swap Price ($)		Daily Volume (Bbls/d)			Swap Price ($)
2012		10,000		5.035		1,000			90.30
2012		10,000		5.040		1,000			90.41
2012		10,000		5.050		1,000			90.45
2012						1,000			95.50
2012						2,000			97.60
2012						1,000			98.15
2012						1,000			100.00
2012						1,000			101.55
2012						1,000			104.25
2012						1,000	†		111.02
2013		10,000		5.270		1,000			94.45
2013		10,000		5.320		1,000			94.60
2013						1,000			97.15
2013						1,000			101.53
2013						1,000			103.00
2013						1,000			104.50
2013						1,000	†		107.30
2014						1,000	†		103.30