Asset Retirement Obligations (Tables)

6 Months Ended

Jun. 30, 2018

Asset Retirement Obligation Disclosure [Abstract]

Summary of Changes in Asset Retirement Obligations

The following table provides a summary of the changes in the Company’s asset retirement obligations:

(in thousands)	Amount
Balance at December 31, 2017	$	10,412
Accretion expense	580
Balance at June 30, 2018	$	10,992