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

3 Months Ended

Mar. 31, 2019

Extractive Industries [Abstract]

Capitalized Costs and Accumulated Depreciation, Depletion and Amortization

	March 31, 2019			December 31, 2018
	(in thousands)
Natural gas and oil properties:
Properties subject to depletion	$	11,193,577		$	10,974,929
Unproved properties		2,106,568			2,110,277
Total		13,300,145			13,085,206
Accumulated depreciation, depletion and amortization		(4,194,876	)		(4,062,021	)
Net capitalized costs	$	9,105,269		$	9,023,185

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