Income Taxes (Tables)

9 Months Ended

Sep. 30, 2017

Income Tax Disclosure [Abstract]

Reconciliation of Income Tax Provision (Benefit)

A reconciliation of the income tax provision (benefit) based on the U.S. federal statutory rate of 35% to the effective income tax rate is as follows:

	THREE MONTHS ENDED						NINE MONTHS ENDED
	SEPTEMBER 30						SEPTEMBER 30
	2017			2016			2017			2016
Income (loss) before income tax provision (benefit)	$	5,956		$	(13,721	)	$	23,347		$	(6,398	)
Statutory taxes (benefit) at 35.0%	$	2,085		$	(4,802	)	$	8,171		$	(2,239	)
Percentage depletion	(1,033		)	(7,889		)	(5,531		)	(12,034		)
State and local income taxes	119			(758		)	187			(788		)
Domestic production deduction	(75		)	(628		)	(371		)	(666		)
Non-deductible expenses	(469		)	991			168			1,701
Valuation allowances	1,923			1,673			1,692			1,690
Uncertain tax positions	7			190			55			(2,015		)
Other, net	68			(366		)	193			381
Income tax provision (benefit)	$	2,625		$	(11,589	)	$	4,564		$	(13,970	)
Effective income tax rate	44.1		%	84.5		%	19.5		%	218.3		%