Asset Retirement Obligations (Tables)

6 Months Ended

Jun. 30, 2011

Asset Retirement Obligations

Asset Retirement Obligations

	Three Months Ended June 30,						Six Months Ended June 30,
	2011			2010			2011			2010
	(in thousands)
Beginning asset retirement obligations	$	154,689		$	142,270		$	152,291		$	166,434
Liabilities assumed in acquisitions		—			6			6			6
New wells placed on production		1,404			4,365			2,075			4,644
Changes in estimates		(179	)		—			121			—
Disposition of wells		(367	)		(3,291	)		(448	)		(29,540	)
Liabilities settled		(6,235	)		(8,801	)		(7,469	)		(9,955	)
Accretion of discount from continuing operations		2,658			2,529			5,313			5,388
Accretion of discount from discontinued operations		—			103			81			204
Ending asset retirement obligations	$	151,970		$	137,181		$	151,970		$	137,181