Asset Retirement Obligations

9 Months Ended

Sep. 30, 2019

Asset Retirement Obligation Disclosure [Abstract]

(11) ASSET RETIREMENT OBLIGATIONS

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. A reconciliation of our liability for plugging and abandonment costs for the nine months ended September 30, 2019 and the year ended December 31, 2018 is as follows (in thousands):

	Nine Months Ended September 30, 2019			Year Ended December 31, 2018
Beginning of period	$	312,754		$	276,855
Liabilities incurred		3,059			3,376
Acquisitions		—			13,438
Liabilities settled		(5,091	)		(5,052	)
Disposition of wells ^(a)		(80,014	)		(13,332	)
Accretion expense		12,289			25,456
Change in estimate		(2,247	)		12,013
End of period		240,750			312,754
Less current portion		(5,485	)		(5,485	)
Long-term asset retirement obligations	$	235,265		$	307,269

^(a) The nine months ended September 30, 2019 represents the completion of the sale of approximately 1,300 shallow, non-core wells in Pennsylvania.

Accretion expense is recognized as a component of depreciation, depletion and amortization expense in the accompanying consolidated statements of operations.