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

9 Months Ended

Sep. 30, 2015

Extractive Industries [Abstract]

Capitalized Costs and Accumulated Depreciation, Depletion and Amortization

	September 30, 2015			December 31, 2014
	(in thousands)
Natural gas and oil properties:
Properties subject to depletion	$	9,716,557		$	9,624,725
Unproved properties		940,064			943,246
Total		10,656,621			10,567,971
Accumulated depreciation, depletion and amortization		(2,871,827	)		(2,590,398	)
Net capitalized costs	$	7,784,794		$	7,977,573

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