Exploratory Costs (Tables)

9 Months Ended

Sep. 30, 2016

Extractive Industries [Abstract]

Schedule of Capitalized Exploratory Wells

The following table sets forth capitalized exploratory well costs and includes additions pending determination of proved reserves, reclassifications to proved reserves and costs charged to expense:

	Three months ended September 30,						Nine months ended September 30,
(in thousands)	2016			2015			2016			2015
Capitalized exploratory well costs at beginning of period	$	37,438		$	99,926		$	103,588		$	119,439
Additions pending determination of proved reserves	88,879			113,734			250,782			533,255
Reclassifications due to determination of proved reserves	(44,564		)	(82,325		)	(272,617		)	(521,359		)
Capitalized exploratory well costs at end of period	$	81,753		$	131,335		$	81,753		$	131,335

The following table sets forth capitalized exploratory well costs:

(in thousands)	September 30, 2016		December 31, 2015
Exploratory wells in progress (drilling rig not released)	$	33,818	$	1,760
Capitalized exploratory well costs capitalized for a period of one year or less	41,048		101,828
Capitalized exploratory well cost for a period greater than one year	6,887		—
Total capitalized exploratory well costs	$	81,753	$	103,588