Income Taxes - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017
Income Taxes [Line Items]
Recognition of a valuation allowance against deferred tax assets in the U.S	$ 4,083	$ 3,654
Effective tax rate	21.00%	34.00%
Earliest Tax Year
Income Taxes [Line Items]
Income tax examination by federal and state tax authorities	2014
Latest Tax Year
Income Taxes [Line Items]
Income tax examination by federal and state tax authorities	2018

Amount of valuation allowance of deferred tax asset attributable to deductible temporary differences and carryforwards, classified as noncurrent.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32537-109319

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 45
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=84176650&loc=d3e31917-109318

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 45
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=84176650&loc=d3e31928-109318

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