Reconciliation of Income Tax Expense to Amount Computed by Applying Current Statutory Tax Rate to Income (Loss) Before Income Taxes (Detail) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
(Loss) income before income taxes	$ 22,272	$ (15,231)	$ (13,254)
PRC tax rate	25.00%	25.00%	25.00%
Tax benefit (tax expense) at PRC tax rate on income (loss) before income tax	$ (5,568)	$ 3,808	$ 3,314
Effect of difference between Hong Kong and PRC tax rates applied to Hong Kong income	(195)	(192)	(530)
Change in valuation allowance	209	870	(2,249)
Non-deductible and non-taxable items	(1,343)	(2,311)	94
Others	318	(135)	$ (629)
Total	$ (6,579)	$ 2,040

Income loss including discontinued operations before income taxes.

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Amount of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to nondeductible expenses or income that is exempt from income taxes under enacted tax laws.

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Percentage of domestic federal statutory tax rate applicable to pretax income (loss).

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Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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Amount of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to increase (decrease) in the valuation allowance for deferred tax assets.

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The amount of income tax expense or benefit for the period computed by applying the domestic federal statutory tax rates to pretax income from continuing operations.

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