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

9 Months Ended

Sep. 30, 2013

Capitalized Costs and Accumulated Depreciation, Depletion and Amortization

	September 30, 2013			December31, 2012
	(in thousands)
Natural gas and oil properties:
Properties subject to depletion	$	7,919,627		$	7,368,308
Unproved properties		748,055			743,467
Total		8,667,682			8,111,775
Accumulated depreciation, depletion and amortization		(2,160,378	)		(2,015,591	)
Net capitalized costs	$	6,507,304		$	6,096,184

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