PROPERTIES AND EQUIPMENT Properties and Equipment (Tables)

12 Months Ended

Dec. 31, 2017

Capitalized Costs of Unproved Properties Excluded from Amortization [Line Items]

Schedule of Capitalized Costs of Unproved Properties Excluded from Amortization [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 consolidated balance sheet:

	2017
	(in thousands, except for number of wells)
Beginning balance	$	—
Additions to capitalized exploratory well costs pending the determination of proved reserves	51,776
Reclassifications to proved properties	(36,328		)
Balance at December 31,	$	15,448
Number of wells pending determination at December 31,	3

Property, Plant and Equipment [Table Text Block]

The following table presents the components of properties and equipment, net of accumulated DD&A:

	As of December 31,
	2017			2016
	(in thousands)
Properties and equipment, net:
Crude oil and natural gas properties
Proved	$	4,356,922		$	3,499,718
Unproved	1,097,317			1,874,671
Total crude oil and natural gas properties	5,454,239			5,374,389
Infrastructure, pipeline, and other	109,359			62,093
Land and buildings	10,960			6,392
Construction in progress	196,024			122,591
Properties and equipment, at cost	5,770,582			5,565,465
Accumulated DD&A	(1,837,115		)	(1,562,471		)
Properties and equipment, net	$	3,933,467		$	4,002,994

Impairment of natural gas and crude oil properties [Table Text Block]

The following table presents impairment charges recorded for properties and equipment:

	Year Ended December 31,
	2017		2016		2015
	(in thousands)
Impairment of proved and unproved properties	$	285,465	$	5,562	$	154,608
Amortization of individually insignificant unproved properties	422		1,379		7,012
Land and buildings	—		3,032		—
Total impairment of properties and equipment	$	285,887	$	9,973	$	161,620