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

9 Months Ended

Sep. 30, 2014

Extractive Industries [Abstract]

Capitalized Costs and Accumulated Depreciation, Depletion and Amortization

	September 30, 2014			December 31, 2013
	(in thousands)
Natural gas and oil properties:
Properties subject to depletion	$	9,193,442		$	8,225,859
Unproved properties		908,673			807,022
Total		10,102,115			9,032,881
Accumulated depreciation, depletion and amortization		(2,472,030	)		(2,274,444	)
Net capitalized costs	$	7,630,085		$	6,758,437

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