Exploratory Costs (Tables)

3 Months Ended

Mar. 31, 2013

Exploratory Cost Disclosure [Abstract]

Capitalized exploratory well and project activity

The following table reflects the Company's capitalized exploratory well and project activity during the three months ended March 31, 2013:

	Three Months Ended March 31, 2013
	(in thousands)
Beginning capitalized exploratory costs	$	212,670
Additions to exploratory costs pending the determination of proved reserves	351,575
Reclassification due to determination of proved reserves	(262,754		)
Exploratory well costs charged to exploration expense	(7,734		)
Ending capitalized exploratory costs	$	293,757

Aging of capitalized exploratory costs and the number of projects for which exploratory costs have been capitalized

The following table provides an aging, as of March 31, 2013 and December 31, 2012, of capitalized exploratory costs and the number of projects for which exploratory costs have been capitalized for a period greater than one year based on the date drilling was completed:

	March 31, 2013		December 31, 2012
	(in thousands, except project counts)
Capitalized exploratory costs that have been suspended:
One year or less	$	174,841	$	190,678
More than one year	118,916		21,992
	$	293,757	$	212,670
Number of projects with exploratory costs that have been suspended for a period greater than one year	2		1