Contingencies and Commitments (Tables)

12 Months Ended

Dec. 31, 2017

Commitments and Contingencies Disclosure [Abstract]

Undiscounted reserve

The undiscounted reserve balance at the beginning of the year, the amounts expensed and paid, and the balance at December 31, 2017 and 2016 are as follows:

(Thousands)	2017			2016
Reserve balance at beginning of year	$	6,041		$	5,714
Expensed	1,006			851
Paid	(548		)	(524		)
Reserve balance at end of year	$	6,499		$	6,041
Ending balance recorded in:
Other liabilities and accrued items	$	987		$	874
Other long-term liabilities	5,512			5,167

Schedule of Change in Asset Retirement Obligation

The following represents a roll forward of our asset retirement obligation liability related to our mine located in Utah for the years ended December 31, 2017 and 2016:

(Thousands)	2017		2016
Asset retirement obligation at beginning of period	$	1,084	$	610
Accretion expense	83		49
Change in liability	—		425
Asset retirement obligation at end of period	$	1,167	$	1,084