Income Taxes (Tables)

12 Months Ended

Dec. 31, 2015

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:

	2015			2014
Deferred tax assets:
Employee benefits	$	1,296		$	1,440
Inventories		7,071			6,966
Natural gas derivatives		4,183			—
Goodwill		3,980			874
Net Operating Loss		39,360			—
Other		1,723			2,942
Foreign losses		1,230			4,300
Foreign tax assets valuation allowance		(1,230	)		(4,300	)
Total deferred tax assets		57,613			12,222
Deferred tax liabilities:
Depreciation		71,976			81,628
Total deferred tax liabilities		71,976			81,628
Net deferred tax liabilities	$	14,363		$	69,406

Significant Components of Provision for Income Taxes

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

	2015			2014		2013
Current:
Federal	$	1,509		$	11,310	$	27,188
State		120			500		2,164
Foreign		966			1,084		842
Total current		2,595			12,894		30,194
Deferred		(56,800	)		24,389		10,121
		$(54,205)		$	37,283	$	40,315

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:

	2015						2014						2013
	Amount			Percent			Amount			Percent			Amount			Percent
U.S. statutory rate	$	(57,312	)		(35.0	)%	$	32,505			35.0	%	$	43,820			35.0	%
State income taxes, net of federal tax benefit		(3,474	)		(2.1	)		1,882			2.0			2,097			1.7
Mining depletion		(1,557	)		(0.9	)		(3,035	)		(3.3	)		(2,751	)		(2.2	)
Change in election to deduct foreign taxes paid		1,442			0.9			—			—			—			—
Foreign tax assets valuation allowance		1,230			0.7			4,300			4.6			—			—
Non-recognized benefit on foreign investments		847			0.5			2,980			3.2			—			—
Section 199 Manufacturing Benefit and other		4,619			2.8			(1,349	)		(1.4	)		(2,851	)		(2.3	)
	$	(54,205	)		(33.1	)%	$	37,283			40.1	%	$	40,315			32.2	%