Properties and Equipment (Tables)

9 Months Ended

Sep. 30, 2019

Oil and Gas Property [Abstract]

Property, Plant and Equipment

The following table presents the components of properties and equipment, net of accumulated depreciation, depletion and amortization ("DD&A"):

	September 30, 2019			December 31, 2018
	(in thousands)
Properties and equipment, net:
Crude oil and natural gas properties
Proved	$	6,153,145		$	5,452,613
Unproved	423,056			492,594
Total crude oil and natural gas properties	6,576,201			5,945,207
Equipment and other	41,667			60,612
Land and buildings	12,312			11,243
Construction in progress	399,732			356,095
Properties and equipment, at cost	7,029,912			6,373,157
Accumulated DD&A	(2,864,756		)	(2,370,295		)
Properties and equipment, net	$	4,165,156		$	4,002,862

Disclosure of Long Lived Assets Held-for-sale [Table Text Block]

The following table presents balance sheet data related to assets and liabilities held-for-sale:

	December 31, 2018
	(in thousands)
Assets
Properties and equipment, net	$	137,448
Other assets	3,257
Total assets	$	140,705
Liabilities
Asset retirement obligations	$	4,111
Total liabilities	$	4,111

Impairment of natural gas and crude oil properties

The following table presents impairment charges recorded for crude oil and natural gas properties:

	Three Months Ended September 30,				Nine Months Ended September 30,
	2019		2018		2019		2018
	(in thousands)
Impairment of proved and unproved properties	$	146	$	1,488	$	10,250	$	194,146
Amortization of individually insignificant unproved properties	—		—		—		84
Impairment of infrastructure and other	21		—		26,771		—
Impairment of properties and equipment	$	167	$	1,488	$	37,021	$	194,230

Schedule of Aging of Capitalized Exploratory Well Costs [Table Text Block]

The following table presents the capitalized exploratory well cost pending determination of proved reserves and included in properties and equipment, net on the condensed consolidated balance sheets:

    

	Nine Months Ended September 30,			Year Ended December 31, 2018
	(in thousands, except for number of wells)
Beginning balance	$	12,188		$	15,448
Additions to capitalized exploratory well costs pending the determination of proved reserves	25,605			35,127
Reclassifications to proved properties	(13,016		)	(38,387		)
Ending balance	$	24,777		$	12,188
Number of wells pending determination at period-end	3			2