Income Taxes (Tables)

12 Months Ended

Dec. 31, 2018

Income Tax Disclosure [Abstract]

Summary of Provision for Income Tax Expense (Benefit)

The provision for income tax (benefit) expense consisted of the following:

	(In thousands) Years Ended December 31,
	2018			2017			2016
Current tax expense
Federal	$	474		$	2,387		$	5,953
State	1,260			525			2,982
	1,734			2,912			8,935
Deferred tax (benefit) expense
Federal	(789		)	(15,515		)	3,876
State	291			135			41
	(498		)	(15,380		)	3,917
Income tax expense (benefit)	$	1,236		$	(12,468	)	$	12,852

Summary of Deferred Tax Assets (Liabilities)

Deferred tax (liabilities) assets were comprised of the following:

	(In thousands) December 31,
	2018			2017
Deferred tax assets:
Accrued expenses	$	704		$	313
Allowance for doubtful accounts	267			208
Contract overrun reserves	1,263			294
Deferred compensation	302			177
Employment-related accruals	4,252			2,091
Environmental reserves	479			501
Federal tax credit carryforwards	288			5,613
Inventory reserves	1,757			1,315
Pension obligation	2,324			2,398
State net operating loss carryforwards	51			86
State tax credit carryforwards	9,075			9,051
Stock-based compensation	1,661			1,480
Workers’ compensation	51			75
Other	1,538			1,492
Total gross deferred tax assets	24,012			25,094
Valuation allowance	(9,083		)	(9,013		)
Total gross deferred tax assets, net of valuation allowance	14,929			16,081
Deferred tax liabilities:
Deferred revenue	(649		)	—
Depreciation	(7,951		)	(7,976		)
Goodwill	(3,963		)	(2,902		)
Intangibles	(19,905		)	(20,611		)
Prepaid insurance	(223		)	(312		)
Total gross deferred tax liabilities	(32,691		)	(31,801		)
Net deferred tax liabilities	$	(17,762	)	$	(15,720	)

Principle Reasons for Variation Between Expected and Effective Tax Rate

The principal reasons for the variation between the statutory and effective tax rates were as follows:

	Years Ended December 31,
	2018	2017	2016
Statutory federal income tax rate	21.0%	35.0%	35.0%
State income taxes (net of federal benefit)	5.3	2.5	5.7
Qualified domestic production activities	—	(2.6)	(2.0)
Stock-based compensation expense	(1.9)	(8.2)	—
Research and development tax credits	(32.0)	(50.6)	(8.6)
Other tax credits	(1.2)	(7.5)	—
Changes in valuation allowance	0.7	10.6	0.9
Non-deductible book expenses	8.2	1.1	0.2
Changes in deferred tax assets	12.1	15.4	1.5
Re-measurement of deferred taxes for 2017 Tax Act	—	(171.3)	—
Changes in tax reserves	1.2	11.4	—
Other	(1.4)	0.4	1.0
Effective income tax (benefit) rate	12.0%	(163.8)%	33.7%

Reconciliation of Unrecognized Tax Benefits

A reconciliation of the beginning and ending amount of unrecognized tax benefits was as follows:

	(In thousands) Years Ended December 31,
	2018			2017			2016
Balance at January 1,	$	5,271		$	3,036		$	2,963
Additions for tax positions related to the current year	419			422			476
Additions for tax positions related to prior years	92			1,953			385
Reductions for tax positions related to prior years	(499		)	(99		)	(567		)
Reductions for lapse of statute of limitations	—			(41		)	(221		)
Balance at December 31,	$	5,283		$	5,271		$	3,036