Income Taxes - Additional Information (Detail) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
Jun. 30, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Federal corporate income tax rate	21.00%	35.00%
Net operating loss carryforwards, expiration	The Company's Federal net operating losses that have been incurred prior to December 31, 2017 will continue to have a 20-year carryforward limitation applied and will need to be evaluated for recoverability in the future as such. Net operating losses incurred after December 31, 2017 will have an indefinite life, but usage will be limited to 80% of taxable income in any given year.
Percentage of net operating loss carryforwards, limitation	80.00%
Net deferred tax asset	$ 11,684	$ 12,072
Aggregate Federal NOL carryforwards		37,859
Federal NOLs subject to an annual limitation		5,140
Federal NOLs not subject to an annual limitation		32,719
Federal NOLs annual limitation		$ 2,779

Net operating loss annual limitation.

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Percentage of net operating loss carryforwards limitation.

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Amount, after allocation of valuation allowances and deferred tax liability, of deferred tax asset attributable to deductible differences and carryforwards, without jurisdictional netting.

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible operating loss carryforwards that are not subject to expiration dates.

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No definition available.

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible operating loss carryforwards that are subject to expiration dates.

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Percentage of domestic federal statutory tax rate applicable to pretax income (loss).

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Amount of operating loss carryforward, before tax effects, available to reduce future taxable income under enacted tax laws.

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A description of the limitations on the use of all operating loss carryforwards available to reduce future taxable income.

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