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

9 Months Ended

Sep. 30, 2016

Extractive Industries [Abstract]

Capitalized Costs and Accumulated Depreciation, Depletion and Amortization

	September 30, 2016			December 31, 2015
	(in thousands)
Natural gas and oil properties:
Properties subject to depletion	$	9,263,853		$	8,047,181
Unproved properties		2,936,529			949,155
Total		12,200,382			8,996,336
Accumulated depreciation, depletion and amortization		(2,994,282	)		(2,635,031	)
Net capitalized costs	$	9,206,100		$	6,361,305

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