Asset Retirement Obligations (Tables)

9 Months Ended

Sep. 30, 2011

Asset Retirement Obligation Disclosure [Abstract]

Asset Retirement Obligations Reconciliation

The following presents a reconciliation of the asset retirement obligations (in thousands):

Asset retirement obligations at December 31, 2010	$	42,945
Liabilities added from acquisitions		6,966
Liabilities added from drilling		917
Current year accretion expense		2,816
Settlements		(1,214	)
Revision of estimate		787
Asset retirement obligations at September 30, 2011	$	53,217