Property and Equipment (Tables)

12 Months Ended

Dec. 31, 2014

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, 2014 and 2013:



	December 31,
In thousands	2014			2013
Oil and natural gas properties
Proved properties	$	9,782,337		$	8,945,326
Unevaluated properties	918,406			780,481
Total	10,700,743			9,725,807
Accumulated depletion and depreciation	(3,679,883		)	(3,219,500		)
Net oil and natural gas properties	7,020,860			6,506,307
CO₂ properties
CO₂ properties	1,162,538			1,117,167
Accumulated depletion and depreciation	(183,646		)	(150,968		)
Net CO₂ properties	978,892			966,199
Pipelines and plants
CO₂ pipelines ⁽¹⁾	1,733,562			1,681,774
Plants	536,002			527,786
Total	2,269,564			2,209,560
Accumulated depletion and depreciation	(182,385		)	(134,697		)
Net plants and pipelines	2,087,179			2,074,863
Other property and equipment
Other property and equipment	468,051			466,969
Accumulated depletion and depreciation	(202,738		)	(163,060		)
Net other property and equipment	265,313			303,909
Net property and equipment	$	10,352,244		$	9,851,278


(1)	Amount includes $98.5 million of CO₂ pipelines at December 31, 2014 that were under construction and not subject to depreciation during 2014.

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, 2014, and the year in which the costs were incurred follows:



	December 31, 2014
	Costs Incurred During:
In thousands	2014		2013		2012		2011 and Prior		Total
Property acquisition costs	$	6,500	$	215,822	$	102,377	$	329,840	$	654,539
Exploration and development	125,783		40,835		22,080		10,361		199,059
Capitalized interest	21,807		24,898		12,084		6,019		64,808
Total	$	154,090	$	281,555	$	136,541	$	346,220	$	918,406