Stock-Based Compensation (Additional Information) (Detail) $ in Millions	6 Months Ended
Jun. 30, 2018 USD ($)
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Total unrecognized compensation cost	$ 2.9
Total unrecognized compensation cost, expected recognition period (in years)	3 years 9 months 18 days

Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (i)
-URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901

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Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration