Capitalized Costs and Accumulated Depreciation, Depletion and Amortization (Tables)

3 Months Ended

Mar. 31, 2013

Capitalized Costs and Accumulated Depreciation, Depletion and Amortization

	March31, 2013	December31, 2012
	(in thousands)
Natural gas and oil properties:
Properties subject to depletion	$7,396,037	$7,368,308
Unproved properties	732,163	743,467
Total	8,128,200	8,111,775
Accumulated depreciation, depletion and amortization	(1,944,252)	(2,015,591)
Net capitalized costs	$6,183,948	$6,096,184

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