Properties and Equipment

12 Months Ended

Dec. 31, 2013

Properties and Equipment

Properties and Equipment

3. Properties and Equipment

        Properties and equipment are comprised of the following:

	December 31,
(In thousands)	2013			2012
Proved oil and gas properties	$	6,362,570		$	5,724,940
Unproved oil and gas properties		375,428			467,483
Gathering and pipeline systems		239,958			239,656
Land, building and other equipment		94,243			86,137
		7,072,199			6,518,216
Accumulated depreciation, depletion and amortization		(2,525,972	)		(2,207,239	)
	$	4,546,227		$	4,310,977

Capitalized Exploratory Well Costs

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

	Year Ended December 31,
(In thousands)	2013			2012			2011
Balance at beginning of period	$	10,390		$	5,328		$	4,285
Additions to capitalized exploratory well costs pending the determination of proved reserves		—			10,390			5,328
Reclassifications to wells, facilities, and equipment based on the determination of proved reserves		(10,198	)		—			(1,138	)
Capitalized exploratory well costs charged to expense		(192	)		(5,328	)		(3,147	)
Balance at end of period	$	—		$	10,390		$	5,328

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

	December 31,
(In thousands)	2013		2012		2011
Capitalized exploratory well costs that have been capitalized for a period of one year or less	$	—	$	10,390	$	5,328
Capitalized exploratory well costs that have been capitalized for a period greater than one year		—		—		—
	$	—	$	10,390	$	5,328