Crude Oil and Natural Gas Property Information (Tables)

12 Months Ended

Dec. 31, 2017

Oil and Gas Exploration and Production Industries Disclosures [Abstract]

Schedule of Results of Operations from Crude Oil and Natural Gas Producing Activities

The following table sets forth the Company’s consolidated results of operations from crude oil and natural gas producing activities for the years ended December 31, 2017, 2016 and 2015.

	Year ended December 31,
In thousands	2017			2016			2015
Crude oil and natural gas sales	$	2,982,966		$	2,026,958		$	2,552,531
Production expenses	(324,214		)	(289,289		)	(348,897		)
Production taxes	(208,278		)	(142,388		)	(200,637		)
Exploration expenses	(12,393		)	(16,972		)	(19,413		)
Depreciation, depletion, amortization and accretion	(1,652,180		)	(1,679,485		)	(1,722,336		)
Property impairments	(237,370		)	(237,292		)	(402,131		)
Income tax benefit (1)	504,475			126,794			33,680
Results from crude oil and natural gas producing activities	$	1,053,006		$	(211,674	)	$	(107,203	)

Schedule of Costs Incurred in Oil and Gas Property Acquisition Exploration and Development Activities

Costs incurred, both capitalized and expensed, in connection with the Company’s consolidated crude oil and natural gas acquisition, exploration and development activities for the years ended December 31, 2017, 2016 and 2015 are presented below:

	Year ended December 31,
In thousands	2017		2016		2015
Property acquisition costs:
Proved	$	8,446	$	5,008	$	557
Unproved	220,875		149,962		168,492
Total property acquisition costs	229,321		154,970		169,049
Exploration Costs	123,461		182,355		241,523
Development Costs	1,695,954		767,148		2,148,530
Total	$	2,048,736	$	1,104,473	$	2,559,102

Schedule of Aggregate Capitalized Costs Related to Crude Oil and Natural Gas Producing Activities

Aggregate capitalized costs relating to the Company’s consolidated crude oil and natural gas producing activities and related accumulated depreciation, depletion and amortization as of December 31, 2017 and 2016 are as follows:

	December 31,
In thousands	2017			2016
Proved crude oil and natural gas properties	$	21,362,199		$	19,802,395
Unproved crude oil and natural gas properties	365,413			429,562
Total	21,727,612			20,231,957
Less accumulated depreciation, depletion and amortization	(8,971,935		)	(7,553,255		)
Net capitalized costs	$	12,755,677		$	12,678,702

Schedule of Capitalized Exploratory Drilling Costs Pending Evaluation

The following table presents the amount of capitalized exploratory drilling costs pending evaluation at December 31 for each of the last three years and changes in those amounts during the years then ended:

	Year ended December 31,
In thousands	2017			2016			2015
Balance at January 1	$	34,852		$	59,397		$	93,421
Additions to capitalized exploratory well costs pending determination of proved reserves	79,451			123,980			132,806
Reclassification to proved crude oil and natural gas properties based on the determination of proved reserves	(81,035		)	(141,941		)	(160,779		)
Capitalized exploratory well costs charged to expense	(1,912		)	(6,584		)	(6,051		)
Balance at December 31	$	31,356		$	34,852		$	59,397
Number of gross wells	37			54			73