Asset Retirement Obligation (Tables)

12 Months Ended

Dec. 31, 2017

Asset Retirement Obligation Disclosure [Abstract]

Summary of Asset Retirement Obligation

Changes to the Company’s asset retirement obligation are summarized below:

	December 31, 2017			December 31, 2016
	(thousands of dollars)
Balance, beginning of period	$	4,789		$	4,468
Liabilities settled		(97	)		(54	)
Accretion expense		1,039			480
Balance, end of period		5,731			4,894
Less: Included in liabilities held for sale		-			(105	)
Less: Current portion		(1,078	)		(121	)
Non-current portion	$	4,653		$	4,668