Costs Incurred for Property Acquisition Exploration and Development (Tables)

9 Months Ended

Sep. 30, 2011

Extractive Industries [Abstract]

Costs Incurred for Property Acquisition, Exploration and Development

	Nine Months Ended		Year
	September 30,		Ended December 31,
	2011		2010
	(in thousands)
Acquisitions:
Unproved leasehold	$	—	$	3,697
Proved properties		542		130,767
Asset retirement obligations		—		556
Acreage purchases		144,652		151,572
Development		762,067		727,720
Exploration:
Drilling		136,181		50,433
Expense		53,270		56,298
Stock-based compensation expense		3,115		4,209
Gas gathering facilities:
Development		37,072		19,627
Subtotal		1,136,899		1,144,879
Asset retirement obligations		13,568		(6,370	)
Total costs incurred — continuing operations		1,150,467		1,138,509
Discontinued operations		3,245		73,369
Total costs incurred	$	1,153,712	$	1,211,878