Accrued Expenses and Other Long-term Liabilities - Summary of Changes in Deferred Revenue (Detail) $ in Thousands	9 Months Ended
Sep. 30, 2018 USD ($)
Deferred Revenue Disclosure [Abstract]
Beginning balance	$ 0
Deferred revenue recorded	1,081
Revenue recognized upon satisfaction of performance obligations in the period	(329)
Ending balance	$ 752

Amount of deferred revenue recognized for transactions arising during the current reporting period. Deferred revenue is a liability as of the balance sheet date related to a revenue producing activity for which revenue has not yet been recognized. Generally, an Entity records deferred revenue when it receives consideration from a customer before achieving certain criteria that must be met for revenue to be recognized in conformity with GAAP.

No definition available.

Name:	us-gaap_DeferredRevenueAdditions
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration