Asset Retirement Obligations (Tables)

9 Months Ended

Sep. 30, 2019

Asset Retirement Obligation Disclosure [Abstract]

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.