Oil and Gas Producing Activities (Tables)

12 Months Ended

Dec. 31, 2015

Oil And Gas Exploration And Production Industries Disclosures [Abstract]

Capitalized Costs Related to Oil and Gas Property Acquisition Exploration and Development Activities

Capitalized Costs

	As of December 31,
	2014			2015
	(In thousands)
Unproved properties	$	201,459		$	84,144
Proved properties:
Leasehold costs		1,006,839			982,915
Wells and related equipment and facilities		3,275,249			3,349,307
Accumulated depreciation depletion and amortization		(2,298,450	)		(3,389,786	)
	$	2,185,097		$	1,026,580

Costs Incurred Related to Oil and Gas Property Acquisition Exploration and Development Activities

Costs Incurred

	For the Years Ended December 31,
	2013		2014		2015
	(In thousands)
Property Acquisitions:
Unproved property acquisitions	$	130,113	$	91,960	$	12,972
Proved property acquisitions		6,471		2,400		—
Development costs		341,970		440,848		221,265
Exploration costs		439		52,080		12,265
	$	478,993	$	587,288	$	246,502