Asset Retirement Obligations (Tables)

9 Months Ended

Sep. 30, 2015

Asset Retirement Obligation Disclosure [Abstract]

Our asset retirement obligations primarily represent the estimated present value of the amounts we will incur to plug, abandon and remediate our producing properties at the end of their productive lives. Significant inputs used in determining such obligations include estimates of plugging and abandonment costs, estimated future inflation rates and well lives. The inputs are calculated based on historical data as well as current estimated costs. In the first nine months 2015, we increased our estimated abandonment costs on certain of our water impoundments and changed estimated well lives for certain wells in Pennsylvania. A reconciliation of our liability for plugging and abandonment costs for the nine months ended September 30, 2015 is as follows (in thousands):

	Nine Months Ended September 30, 2015
Beginning of period	$	287,463
Liabilities incurred		4,135
Liabilities settled		(13,205	)
Disposition of wells		(4,116	)
Accretion expense		14,521
Change in estimate		15,727
End of period		304,525
Less current portion		(17,689	)
Long-term asset retirement obligations	$	286,836