Suspended Well Costs (Tables)

12 Months Ended

Dec. 31, 2012

Suspended Well Costs [Abstract]

Capitalized Exploratory Well Costs, Roll Forward [Table Text Block]

The following table reflects the net changes in capitalized exploratory well costs during 2012, 2011, and 2010. The table does not include amounts that were capitalized and either subsequently expensed or reclassified to producing well costs in the same year:

	For the Years Ended December 31,
	2012			2011			2010
	(in thousands)
Beginning balance on January 1,	$	18,600		$	35,862		$	34,384
Additions to capitalized exploratory well costs pending the determination of proved reserves	9,100			15,618			35,862
Reclassifications to wells, facilities, and equipment based on the determination of proved reserves	(5,865		)	(32,880		)	(34,384		)
Capitalized exploratory well costs charged to expense	(12,735		)	—			—
Ending balance at December 31,	$	9,100		$	18,600		$	35,862

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

The following table provides an aging of capitalized exploratory well costs based on the date the drilling was completed and the number of projects for which exploratory well costs have been capitalized for more than one year since the completion of drilling:

	As of December 31,
	2012		2011		2010
	(in thousands)
Exploratory well costs capitalized for one year or less	$	9,100	$	15,618	$	35,862
Exploratory well costs capitalized for more than one year	—		2,982		—
Ending balance at December 31,	$	9,100	$	18,600	$	35,862
Number of projects with exploratory well costs that have been capitalized more than a year	—		2		—