Income Taxes (Tables)

12 Months Ended

Dec. 31, 2016

Significant Components of Deferred Tax Assets and Liabilities

Significant components of the Company’s deferred tax assets and liabilities as of December 31 are as follows:

	2016		2015
Deferred tax assets:
Employee benefits	$	1,349	$	1,296
Inventories		8,811		7,071
Natural gas derivatives		1,281		4,183
Goodwill & other intangibles		4,881		3,980
Net operating loss		51,722		39,360
Other		2,027		1,723
Foreign losses		—		1,230
Foreign tax assets valuation allowance		—		(1,230	)
Total deferred tax assets		70,071		57,613
Deferred tax liabilities:
Depreciation		71,308		71,976
Total deferred tax liabilities		71,308		71,976
Net deferred tax liabilities	$	1,237	$	14,363

Significant Components of Provision for Income Taxes

Significant components of the provision for income taxes for the years ended December 31 are as follows:

	2016			2015			2014
Current:
Federal	$	(495	)	$	1,509		$	11,310
State		(496	)		120			500
Foreign		445			966			1,084
Total current		(546	)		2,595			12,894
Deferred		(50,535	)		(56,800	)		24,389
	$	(51,081	)	$	(54,205	)	$	37,283

Reconciliation of Income Taxes Computed at U.S. Statutory Tax Rate to Income Tax Expense

The reconciliation of income taxes computed at the U.S. statutory tax rate to the Company’s income tax expense for the years ended December 31 is as follows:

	2016						2015						2014
	Amount			Percent			Amount			Percent			Amount			Percent
U.S. statutory rate	$	(45,923	)		(35.0	)%	$	(57,312	)		(35.0	)%	$	32,505			35.0	%
State income taxes, net of federal tax benefit		(3,283	)		(2.5	)		(3,474	)		(2.1	)		1,882			2.0
Mining depletion		(378	)		(0.3	)		(1,557	)		(0.9	)		(3,035	)		(3.3	)
Change in election for foreign tax credits		(2,753	)		(2.1	)		1,442			0.9			—			—
Foreign tax assets valuation allowance		—			—			1,230			0.7			4,300			4.6
Foreign investments		(323	)		(0.2	)		847			0.5			2,980			3.2
Stock compensation excess tax deficiency		789			0.6			—			—			—			—
Other permanent differences		790			0.6			4,619			2.8			(1,349	)		(1.4	)
	$	(51,081	)		(38.9	)%	$	(54,205	)		(33.1	)%	$	37,283			40.1	%