Asset Retirement Obligations (Tables)

6 Months Ended

Jun. 30, 2018

Asset Retirement Obligation Disclosure [Abstract]

Schedule of Asset Retirement Obligations

The changes in asset retirement obligations for the six months ended June 30, 2018 and the year ended December 31, 2017 are as follows:

	Six months ended			Year ended
	June 30, 2018			December 31, 2017
	(in thousands)
Balance at beginning of period (including current portion)	$	18,662		$	19,108
Accretion expense		639			1,493
Adjustment resulting from disposal of property		-			(223	)
Adjustments to the liability from annual recosting and other		-			(1,656	)
Liabilities settled		(158	)		(60	)
Balance at end of period		19,143			18,662
Less current portion of asset retirement obligation		(498	)		(498	)
Long-term portion of asset retirement obligation	$	18,645		$	18,164