Employee Benefit and Bonus Plans - Additional Information (Detail)	12 Months Ended
Dec. 31, 2018 USD ($) Employees	Dec. 31, 2017 USD ($)
Employee Benefit And Bonus Plans [Line Items]
Contributions to the plan	$ 0	$ 0
Executive Performance
Employee Benefit And Bonus Plans [Line Items]
Number of employees who are covering executive performance of bonus plan \| Employees	4
Amount recorded under the plan	$ 400,000	$ 300,000

The carrying amount of the liability as of the balance sheet date to an individual under a deferred compensation arrangement. This amount may be the result of periodic accruals made over the period of active employment, or reflect termination benefits resulting contractual terms or a death benefit.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 710
-SubTopic 10
-Section 30
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6409875&loc=d3e20015-108363

Name:	us-gaap_DeferredCompensationArrangementWithIndividualRecordedLiability
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant