Income Taxes (Tables)

12 Months Ended

Dec. 31, 2018

Income Tax Disclosure [Abstract]

Income tax expenses benefit

Income (loss) before income taxes and income tax expense (benefit) are comprised of the following:

(Thousands)	2018			2017		2016
Income before income taxes:
Domestic	$	20,272		$	28,327	$	13,934
Foreign	(3,930		)	8,069		11,381
Total income before income taxes	$	16,342		$	36,396	$	25,315
Income tax expense:
Current income tax expense:
Domestic	$	(5,896	)	$	1,912	$	6,505
Foreign	2,710			2,777		2,080
Total current	$	(3,186	)	$	4,689	$	8,585
Deferred income tax (benefit) expense:
Domestic	$	(4,083	)	$	19,935	$	(8,842	)
Foreign	2,765			321		(168		)
Total deferred	$	(1,318	)	$	20,256	$	(9,010	)
Total income tax (benefit) expense	$	(4,504	)	$	24,945	$	(425	)

Effective income tax rate reconciliation

A reconciliation of the U.S. federal statutory income tax rate to the Company's effective income tax rate is as follows:

	2018		2017		2016
U.S. federal statutory rate	21.0	%	35.0	%	35.0	%
State and local income taxes, net of federal tax effect	0.1		2.3		(0.4	)
Effect of excess of percentage depletion over cost depletion	(17.8	)	(10.0	)	(10.6	)
Manufacturing production deduction, including impact of NOL carryback	6.3		(0.8	)	(3.3	)
Foreign derived intangible income deduction	(2.9	)	—		—
Tax Cuts and Jobs Act impact	(67.8	)	47.1		—
Foreign rate differential	1.5		(3.4	)	(5.9	)
Research and development tax credit	(7.6	)	(2.6	)	(6.6	)
Foreign tax credit	(1.9	)	(1.1	)	(28.1	)
Foreign repatriation	2.0		1.3		13.7
Incremental fixed asset basis	—		(3.4	)	—
Adjustment to unrecognized tax benefits	2.7		2.8		3.2
Stock compensation - excess tax benefits	(4.4	)	(1.9	)	—
Valuation allowance	38.7		2.4		0.1
Other items	2.5		0.8		1.2
Effective tax rate	(27.6	)%	68.5	%	(1.7	)%

Deferred tax assets and liabilities

Deferred tax assets and (liabilities) recorded in the Consolidated Balance Sheets consist of the following:

	December 31,
(Thousands)	2018			2017
Asset (liability)
Post-employment benefits other than pensions	$	2,198		$	2,787
Other reserves	693			1,371
Deferred compensation	3,539			5,054
Environmental reserves	1,463			1,452
Inventory	3,032			4,636
Pensions	8,105			14,307
Accrued compensation expense	6,215			2,852
Net operating loss and credit carryforwards	12,002			6,374
Research and development tax credit carryforward	744			2,466
Foreign tax credit carryforward	2,385			9,481
Subtotal	40,376			50,780
Valuation allowance	(15,917		)	(16,246		)
Total deferred tax assets	24,459			34,534
Depreciation	(10,280		)	(10,250		)
Amortization	(3,635		)	(2,900		)
Mine development	(5,123		)	(3,621		)
Capitalized interest expense	—			(112		)
Derivative instruments and hedging activities	—			(817		)
Total deferred tax liabilities	(19,038		)	(17,700		)
Net deferred tax asset	$	5,421		$	16,834

Reconciliation of unrecognized tax benefits

A reconciliation of the Company’s unrecognized tax benefits for the year-to-date periods ended December 31, 2018 and 2017 is as follows:

(Thousands)	2018			2017
Balance at January 1	$	2,944		$	2,048
Additions to tax provisions related to the current year	443			163
Additions to tax positions related to prior years	4			1,210
Reduction to tax positions related to prior years	(508		)	(121		)
Lapses on statutes of limitations	—			(356		)
Balance at December 31	$	2,883		$	2,944