Capitalized Costs and Accumulated Depreciation, Depletion and Amortization

3 Months Ended

Mar. 31, 2013

Capitalized Costs and Accumulated Depreciation, Depletion and Amortization

(16) Capitalized Costs and Accumulated Depreciation, Depletion and Amortization (a)

	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.