Income Taxes - Net Deferred Tax Assets and Liabilities (Detail) $ in Thousands	Dec. 31, 2018 USD ($)
Net deferred tax assets (liability):
Deferred tax assets, non-current	$ 7
Net deferred tax assets	7
Deferred tax assets, non-current	$ 7

Amount after allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences and carryforwards classified as noncurrent.

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