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

6 Months Ended

Jun. 30, 2016

Extractive Industries [Abstract]

Capitalized Costs and Accumulated Depreciation, Depletion and Amortization

	June 30, 2016			December 31, 2015
	(in thousands)
Natural gas and oil properties:
Properties subject to depletion	$	8,074,869		$	8,047,181
Unproved properties		930,142			949,155
Total		9,005,011			8,996,336
Accumulated depreciation, depletion and amortization		(2,864,358	)		(2,635,031	)
Net capitalized costs	$	6,140,653		$	6,361,305

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