Asset Retirement Obligations (Tables)
9 Months Ended
Sep. 30, 2017
Asset Retirement Obligation Disclosure [Abstract]  
Schedule of Asset Retirement Obligations
The following table summarizes the changes in the Company’s asset retirement obligations (“ARO”) for the nine months ended September 30, 2017 (in thousands):
Asset retirement obligations at January 1, 2017
$
7,226

Additional liabilities incurred
1,813

Liabilities settled
(65
)
Accretion expense
376

Revision to estimated cash flows
(22
)
Asset retirement obligations at September 30, 2017
$
9,328