Property and Equipment (Tables)

12 Months Ended

Dec. 31, 2013

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, 2013 and 2012:



	December 31,
In thousands	2013			2012
Oil and natural gas properties
Proved properties	$	8,945,326		$	6,963,211
Unevaluated properties	780,481			809,154
Total	9,725,807			7,772,365
Accumulated depletion and depreciation	(3,219,500		)	(2,827,256		)
Net oil and natural gas properties	6,506,307			4,945,109
CO₂ properties
CO₂ properties	1,117,167			1,032,653
Accumulated depletion and depreciation	(150,968		)	(119,784		)
Net CO₂ properties	966,199			912,869
Pipelines and plants
CO₂ pipelines ⁽¹⁾	1,681,774			1,632,255
Plants	527,786			402,871
Total	2,209,560			2,035,126
Accumulated depletion and depreciation	(134,697		)	(99,185		)
Net plants and pipelines	2,074,863			1,935,941
Other property and equipment
Other property and equipment	466,969			417,207
Accumulated depletion and depreciation	(163,060		)	(134,016		)
Net other property and equipment	303,909			283,191
Net property and equipment	$	9,851,278		$	8,077,110


(1)	Amounts include $48.4 million of CO₂ pipelines at December 31, 2013 that were under construction and not subject to depreciation during 2013.

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

A summary of the unevaluated property costs excluded from oil and natural gas properties being amortized at December 31, 2013, and the year in which the costs were incurred follows:



	December 31, 2013
	Costs Incurred During:
In thousands	2013		2012		2011		2010 and prior		Total
Property acquisition costs	$	215,822	$	109,275	$	12,543	$	317,226	$	654,866
Exploration and development	41,157		22,080		7,408		10,825		81,470
Capitalized interest	25,222		12,084		6,018		821		44,145
Total	$	282,201	$	143,439	$	25,969	$	328,872	$	780,481