Organization, Basis of Presentation and Summary of Significant Policies - Schedule of Impact of Adoption of Topic 842 on Condensed Balance Sheet (Detail) - USD ($) $ in Thousands	Mar. 31, 2019	Jan. 01, 2019	Dec. 31, 2018
Basis Of Presentation [Line Items]
Property and equipment, net	$ 3,952	$ 4,011	$ 3,072
Current liabilities	23,484	21,751	21,539
Other long-term liabilities	6,355	$ 6,422	$ 5,600
Accounting Standards Update 2016-02 [Member] \| Right Of Use Asset [Member]
Basis Of Presentation [Line Items]
Property and equipment, net	939
Accounting Standards Update 2016-02 [Member] \| Lease Liability [Member]
Basis Of Presentation [Line Items]
Current liabilities	212
Other long-term liabilities	$ 822

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