Income Taxes - Summary of Components of Deferred and Other Tax Assets and Liabilities (Parenthetical) (Detail) $ in Thousands	9 Months Ended
Sep. 30, 2018 USD ($)
Income Tax Disclosure [Abstract]
Net operating loss carryforwards	$ 11,148
Net operating loss carryforwards expiration period	Expire at various dates between December 31, 2026 and December 31, 2035.
Net operating loss carryforwards assets	$ 2,057

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

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32559-109319

Name:	us-gaap_OperatingLossCarryforwards
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant