Asset Retirement Obligations (Tables)

9 Months Ended

Sep. 30, 2018

Asset Retirement Obligation Disclosure [Abstract]

Schedule of changes in Company's asset retirement obligations

The following table summarizes the changes in the Company’s asset retirement obligations for the nine months ended September 30, 2018 (in thousands).

Beginning asset retirement obligations	$	26,256
Liabilities incurred during period	2,473
Liabilities settled during period	(663		)
Revisions in estimated cash flows	442
Accretion expense	1,126
Ending asset retirement obligations	29,634
Less: current asset retirement obligations(1)	(928		)
Long-term asset retirement obligations	$	28,706

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(1) Included in accrued liabilities in the Company’s interim unaudited condensed consolidated balance sheet at September 30, 2018.