Asset Retirement Obligations (Tables)

6 Months Ended

Jun. 30, 2012

Asset Retirement Obligations [Abstract]

ARO operating costs

	Three Months Ended June 30				Six Months Ended June 30
in thousands	2012		2011		2012		2011
ARO Operating Costs
Accretion	$	1,998	$	2,124	$	4,017	$	4,296
Depreciation		1,863		1,853		3,727		3,395
Total	$	3,861	$	3,977	$	7,744	$	7,691

Reconciliations of ARO

	Three Months Ended June 30						Six Months Ended June 30
in thousands	2012			2011			2012			2011
Asset Retirement Obligations
Balance at beginning of period		$155,402			$162,591			$153,979			$162,730
Liabilities incurred		45			278			45			278
Liabilities settled		(798	)		(3,632	)		(1,419	)		(5,964	)
Accretion expense		1,998			2,124			4,017			4,296
Revisions down, net		(6,234	)		(628	)		(6,209	)		(607	)
Balance at end of period		$150,413			$160,733			$150,413			$160,733