Properties and Equipment, Net (Tables)

12 Months Ended

Dec. 31, 2018

Property, Plant and Equipment [Abstract]

Components of net property and equipment

Properties and equipment, net are comprised of the following:

	December 31,
(In thousands)	2018			2017
Proved oil and gas properties	$	5,717,145		$	4,932,512
Unproved oil and gas properties	194,435			190,474
Gathering and pipeline systems	83			1,569
Land, building and other equipment	94,714			82,670
	6,006,377			5,207,225
Accumulated depreciation, depletion and amortization	(2,542,771		)	(2,135,021		)
	$	3,463,606		$	3,072,204

Summary of Assets Held-for-sale

Balance sheet data related to the assets held for sale is as follows:

(In thousands)	December 31, 2017
ASSETS
Inventories	$	1,440
Properties and equipment, net	778,855
	780,295
LIABILITIES
Accounts payable	2,352
Asset retirement obligations	15,748
	18,100
Net assets held for sale	$	762,195

Schedule of net changes in capitalized exploratory well costs

The following table reflects the net changes in capitalized exploratory well costs:

	Year Ended December 31,
(In thousands)	2018			2017		2016
Balance at beginning of period	$	19,511		$	—	$	—
Additions to capitalized exploratory well costs pending the determination of proved reserves	—			19,511		—
Reclassifications to wells, facilities, and equipment based on the determination of proved reserves	—			—		—
Capitalized exploratory well costs charged to expense	(19,511		)	—		—
Balance at end of period	$	—		$	19,511	$	—

Schedule of aging of capitalized exploratory well costs

The following table provides an aging of capitalized exploratory well costs based on the date the drilling was completed:

	December 31,
(In thousands)	2018		2017		2016
Capitalized exploratory well costs that have been capitalized for a period of one year or less	$	—	$	19,511	$	—
Capitalized exploratory well costs that have been capitalized for a period greater than one year	—		—		—
	$	—	$	19,511	$	—