Costs Incurred for Property Acquisition, Exploration and Development (Tables)

6 Months Ended

Jun. 30, 2016

Extractive Industries [Abstract]

Costs Incurred for Property Acquisition, Exploration and Development

	Six Months Ended June 30, 2016		Year Ended December 31, 2015
	(in thousands)
Acreage purchases	$	8,873	$	73,025
Development		219,386		708,268
Exploration:
Drilling		30,914		87,505
Expense		10,637		18,421
Stock-based compensation expense		1,061		2,985
Gas gathering facilities:
Development		1,054		13,337
Subtotal		271,925		903,541
Asset retirement obligations		3,740		22,184
Total costs incurred	$	275,665	$	925,725

^(a) Includes costs incurred whether capitalized or expensed.