Income Taxes - Summary of Income Tax Expense (Detail) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Current – federal	$ 7,520	$ 8,978	$ 6,181
Current – state	66	29	(33)
Deferred – federal	(1,076)	376	1,023
Deferred tax adjustment related to reduction in U.S. federal statutory income tax rate	0	3,009	0
Income tax expense	$ 6,510	$ 12,392	$ 7,171

Amount of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations, attributable to increase (decrease) in the income tax rates.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 13
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 12
-URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32687-109319

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