Derivative Instruments And Hedging Activities (Tables)

12 Months Ended

Dec. 31, 2012

Derivative Instruments and Hedging Activities [Abstract]

Schedule of Derivative Instruments Outstanding

	Fixed-Price Swaps
	Daily Average				Average
	Volume		Volume		Swap Price
Remaining Contract Term	(Bbls)		(Bbls)		($/Bbl)
January 2013		13,292		412,050	$	105.33
February 2013		13,264		371,400		105.18
March 2013		12,792		396,550		104.88
April 2013		12,783		383,500		104.73
May 2013		12,727		394,550		104.63
June 2013		12,217		366,500		104.41
July 2013		9,510		294,800		104.25
August 2013		6,219		192,800		104.70
September 2013		6,233		187,000		104.44
October 2013		5,719		177,300		103.94
November 2013		6,233		187,000		103.93
December 2013		9,156		283,850		103.24
2013 Total		9,993		3,647,300		104.57
January 2014		10,500		325,500		100.99
February 2014		10,500		294,000		100.99
March 2014		10,500		325,500		100.99
April 2014		8,500		255,000		101.08
May 2014		8,500		263,500		101.08
June 2014		8,500		255,000		101.08
July 2014		8,500		263,500		101.08
August 2014		5,500		170,500		100.94
September 2014		5,500		165,000		100.94
October 2014		5,500		170,500		100.94
November 2014		5,500		165,000		100.94
December 2014		5,500		170,500		100.94
2014 Total		7,736		2,823,500		101.06
January 2015 - December 2015		1,000		365,000		97.55

	Collars
	Daily Average				Average
	Volume		Volume		Swap Price
Remaining Contract Term	(Bbls)		(Bbls)		($/Bbl)
January 2013—December 2013		1,000		365,000	$	80.00/104.10

Gas Contracts

	Fixed-Price Swaps
	Daily Average				Average
	Volume		Volume		Swap Price
Remaining Contract Term	(Mmbtu)		(Mmbtu)		($/Mmbtu)
January 2013		13,000		403,000	$	3.41
February 2013		13,000		364,000		3.43
March 2013		11,000		341,000		3.42
April 2013		11,000		330,000		3.42
May 2013		10,000		310,000		3.46
June 2013		9,000		270,000		3.50
July 2013		9,000		279,000		3.53
August 2013		8,500		263,500		3.55
September 2013		8,500		255,000		3.55
October 2013		8,000		248,000		3.58
November 2013		7,500		225,000		3.67
December 2013		6,500		201,500		3.83
2013 Total		9,562		3,490,000		3.51
January 2014 - December 2014		5,000		1,825,000		4.01
January 2015 - December 2015		4,300		1,569,500		4.31

Components of Gain (Loss) on Derivative Instruments

	Year Ended December 31,
	2012		2011		2010
	(in thousands)
Unrealized gain (loss) due to change in fair market value	$	(9,491)	$	11,475	$	3,500
Realized loss on settlement		(3,814)		(17,345)		(8,365)
Total loss on derivative instruments	$	(13,305)	$	(5,870)	$	(4,865)