Asset Retirement Obligations (Tables)

6 Months Ended

Jun. 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 six months ended June 30, 2018 (in thousands).

Beginning asset retirement obligations	$	26,256
Liabilities incurred during period	1,589
Liabilities settled during period	(459		)
Accretion expense	739
Ending asset retirement obligations	28,125
Less: current asset retirement obligations(1)	(1,235		)
Long-term asset retirement obligations	$	26,890

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