Asset Retirement Obligations

6 Months Ended

Jun. 30, 2020

Asset Retirement Obligation Disclosure [Abstract]

(10) 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 six months ended June 30, 2020 and the year ended December 31, 2019 is as follows (in thousands):

	Six Months Ended June 30, 2020			Year Ended December 31, 2019
Beginning of period	$	251,076		$	312,754
Liabilities incurred		1,618			4,063
Acquisitions		123			—
Liabilities settled		(1,416	)		(5,953	)
Disposition of wells ^(a)		(126,268	)		(82,576	)
Accretion expense		4,729			15,658
Change in estimate		2,507			7,130
End of period		132,369			251,076
Less current portion		(2,393	)		(2,393	)
Long-term asset retirement obligations	$	129,976		$	248,683

^(a) The six months ended June 30, 2020 primarily represents the completion of the sale of our shallow legacy assets in Northwest Pennsylvania.

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