Income Taxes (Tables)

12 Months Ended

Dec. 31, 2017

Schedule of Components of Income Tax Expense (Benefit)

The provision for income taxes consisted of the following:



	For the years ended
(dollars in thousands)	December 31, 2017			December 31, 2016			December 31, 2015
Current tax provision:
Federal	$	91,762		$	57,605		$	60,826
State	12,274			6,933			7,164
Foreign	66			41			11
Total current provision	104,102			64,579			68,001

Deferred tax provision:
Federal	(6,833		)	9,391			(9,855		)
State	2,532			2,644			(2,216		)
Foreign	(5		)	(47		)	—
Total deferred (benefit) provision	(4,306		)	11,988			(12,071		)
Total provision	$	99,796		$	76,567		$	55,930

Schedule of Income (Loss) before Income Tax, Domestic and Foreign

Components of income (loss) before income taxes are as follows:



	For the years ended
	December 31, 2017			December 31, 2016			December 31, 2015

United States	$	298,994		$	211,419		$	147,427
Foreign	(5,669		)	(4,611		)	(2,109		)
Total income before income taxes	$	293,325		$	206,808		$	145,318

Schedule of Effective Income Tax Rate Reconciliation

A reconciliation of the federal statutory rate to our effective rate is as follows:



	For the years ended
	December 31, 2017		December 31, 2016		December 31, 2015

Federal statutory income tax rate	35.0	%	35.0	%	35.0	%
State income taxes, net of federal income tax benefit	3.4		3.3		2.5
Non-deductible expenses	0.3		0.7		2.0
Domestic manufacturing deduction	(1.6	)	(1.4	)	(1.3	)
Unrecognized tax benefits	1.3		0.5		0.8
Valuation allowance	—		0.5		0.5
Stock option exercises	(2.6	)	(0.7	)	—
Impact of Tax Act	(1.8	)	—		—
Other	—		(0.9	)	(1.0	)
Total	34.0	%	37.0	%	38.5	%

Summary of Unrecognized Tax Benefits

The following is a reconciliation of the beginning and ending amount of unrecognized tax benefits (which excludes federal benefits of state taxes, interest, and penalties):



(dollars in thousands)
Balance at December 31, 2014	$	7,518
Increases in uncertain tax benefits as a result of tax positions taken in the current year	1,845
Decreases in uncertain tax benefits from a lapse of applicable statute of limitations	(156		)
Balance at December 31, 2015	$	9,207
Increases in uncertain tax benefits as a result of tax positions taken in a prior year	287
Increases in uncertain tax benefits as a result of tax positions taken in the current year	1,367
Decreases in uncertain tax benefits from a lapse of applicable statute of limitations	(233		)
Decreases in uncertain tax benefits as a result of tax positions taken in a prior year	(2,028		)
Balance at December 31, 2016	$	8,600
Increases in uncertain tax benefits as a result of tax positions taken in a prior year	1,013
Increases in uncertain tax benefits as a result of tax positions taken in the current year	545
Decreases in uncertain tax benefits from a lapse of applicable statute of limitations	(739		)
Decreases in uncertain tax benefits as a result of tax positions taken in a prior year	(93		)
Balance at December 31, 2017	$	9,326

Schedule of Deferred Tax Assets and Liabilities

Components of deferred tax assets and liabilities were as follows:



(dollars in thousands)	December 31, 2017			December 31, 2016
Deferred tax assets:
Inventories	$	2,010		$	1,440
Accrued liabilities	249			413
Stock-based compensation	1,587			2,544
Long-term incentive plan	849			1,600
State net operating loss carryforwards	317			1,509
Foreign net operating loss carryforwards	2,740			1,380
State tax credits	1,514			1,447
Federal benefit related to uncertain tax positions	1,922			2,724
Other	664			1,057
Deferred tax assets, gross	11,852			14,114
Valuation allowance	(3,489		)	(1,772		)
Total deferred tax assets, net	8,363			12,342

Deferred tax liabilities:
Property, plant, and equipment	(14,910		)	(22,173		)
Other	(496		)	(1,518		)
Total deferred tax liabilities	(15,406		)	(23,691		)

Net deferred tax liabilities	$	(7,043	)	$	(11,349	)