Asset Retirement Obligations (Tables)

3 Months Ended

Mar. 31, 2013

Asset Retirement Obligations

Schedule of changes in asset retirement obligations

	March 31,
	2013
	(In thousands)
Asset retirement obligations:
Beginning asset retirement obligations	$	27,484
Liabilities incurred during period	1,676
Revisions in estimated retirement obligations	—
Liabilities settled during period	—
Accretion expense	797
Ending asset retirement obligations	$	29,957