Capitalized Costs and Accumulated Depreciation, Depletion and Amortization

6 Months Ended

Jun. 30, 2012

Suspended Exploratory Well Costs/Capitalized Costs and Accumulated Depreciation, Depletion and Amortization/Costs Incurred for Property Acquisition, Exploration and Development [Abstract]

Capitalized Costs and Accumulated Depreciation, Depletion and Amortization

(17) Capitalized Costs and Accumulated Depreciation, Depletion and Amortization ^(a)

	June 30, 2012		December 31, 2011
	(in thousands)
Natural gas and oil properties:
Properties subject to depletion	$	6,779,021	$	6,035,429
Unproved properties		817,409		748,598
Total		7,596,430		6,784,027
Accumulated depreciation, depletion and amortization		(1,825,390)		(1,626,461)
Net capitalized costs	$	5,771,040	$	5,157,566

^(a) Includes capitalized asset retirement costs and the associated accumulated amortization.