Property and Equipment (Tables)

12 Months Ended

Dec. 31, 2012

Property, Plant and Equipment [Abstract]

Summary of Property and Equipment

The following table summarizes our property and equipment as of the dates presented: 

	As of December 31,
	2012			2011
Oil and gas properties:
Proved	$	2,277,811		$	2,239,186
Unproved	60,746			120,288
Total oil and gas properties	2,338,557			2,359,474
Other property and equipment	93,648			143,285
Total property and equipment	2,432,205			2,502,759
Accumulated depreciation, depletion and amortization	(708,846		)	(725,184		)
	$	1,723,359		$	1,777,575

Capitalized Exploratory Well Costs, Roll Forward

The following table describes the changes in capitalized exploratory drilling costs that are pending the determination of proved reserves for the periods presented: 

	2012			2011					2010
	Number of Wells	Cost		Number of Wells		Cost			Number of Wells	Cost
Balance at beginning of year	—	$	—	1		$	6,180		—	$	—
Additions pending determination of proved reserves	1	4,435		—		—			1	6,180
Reclassification to wells, equipment and facilities based on the determination of proved reserves	—	—		—		—			—	—
Charged to exploration expense	—	—		(1	)	(6,180		)	—	—
Balance at end of year	1	$	4,435	—		$	—		1	$	6,180