Asset Retirement Obligations (Tables)

6 Months Ended

Jun. 30, 2011

Asset Retirement Obligations [Abstract]

ARO operating costs

	Three Months Ended				Six Months Ended
	June 30				June 30
in thousands	2011		2010		2011		2010
ARO Operating Costs
Accretion		$2,124		$2,255		$4,296		$4,444
Depreciation		1,853		3,157		3,395		6,340
Total		$3,977		$5,412		$7,691		$10,784

Reconciliations of ARO

	Three Months Ended						Six Months Ended
	June 30						June 30
in thousands	2011			2010			2011			2010
Asset Retirement Obligations
Balance at beginning of period		$162,591			$163,931			$162,730			$167,757
Liabilities incurred		278			1,441			278			1,441
Liabilities settled		(3,632	)		(1,740	)		(5,964	)		(4,117	)
Accretion expense		2,124			2,255			4,296			4,444
Revisions up (down)		(628	)		(3,719	)		(607	)		(7,357	)
Balance at end of period		$160,733			$162,168			$160,733			$162,168