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

3 Months Ended

Mar. 31, 2014

Costs Incurred for Property Acquisition, Exploration and Development

	Three Months Ended March 31, 2014		Year Ended December 31, 2013
	(in thousands)
Acreage purchases	$	48,597	$	137,538
Development		223,912		938,668
Exploration:
Drilling		7,737		189,742
Expense		13,694		60,384
Stock-based compensation expense		1,153		4,025
Gas gathering facilities:
Development		3,618		47,086
Subtotal		298,711		1,377,443
Asset retirement obligations		3,218		76,373
Total costs incurred	$	301,929	$	1,453,816

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