Property And Equipment (Tables)

12 Months Ended

Dec. 31, 2012

Property, Plant and Equipment [Abstract]

Summary of net property and equipment balances

The following table presents a summary of our net property and equipment balances as of December 31, 2012 and 2011:

	December 31,
In thousands	2012			2011
Oil and natural gas properties
Proved properties	$	6,963,211		$	7,026,579
Unevaluated properties	809,154			1,157,106
Total	7,772,365			8,183,685
Accumulated depletion and depreciation	(2,827,256		)	(2,407,520		)
Net oil and natural gas properties	4,945,109			5,776,165
CO2 properties
CO2 properties	1,032,653			596,003
Accumulated depletion and depreciation	(119,784		)	(91,666		)
Net CO2 properties	912,869			504,337
Pipelines and plants
CO2 pipelines (1)	1,632,255			1,432,646
Plants under construction (2)	402,871			269,110
Total	2,035,126			1,701,756
Accumulated depletion and depreciation	(99,185		)	(65,392		)
Net plants and pipelines	1,935,941			1,636,364
Other property and equipment
Other property and equipment	417,207			157,674
Accumulated depletion and depreciation	(134,016		)	(62,915		)
Net other property and equipment	283,191			94,759
Net property and equipment	$	8,077,110		$	8,011,625

(1) Amounts include $346.5 million of CO₂ pipelines at December 31, 2012 that were not subject to depreciation during 2012.

(2) Plants under construction are not subject to depreciation.

Summary of unevaluated properties excluded from oil and natural gas properties being amortized

A summary of the unevaluated properties excluded from oil and natural gas properties being amortized at December 31, 2012, and the year in which they were incurred follows:

	December 31, 2012
	Costs Incurred During:
In thousands	2012		2011		2010		2009 and prior		Total
Property acquisition costs	$	110,658	$	12,543	$	351,712	$	115,075	$	589,988
Exploration and development	106,075		40,152		3,155		8,390		157,772
Capitalized interest	29,249		30,430		333		1,382		61,394
Total	$	245,982	$	83,125	$	355,200	$	124,847	$	809,154