Income Taxes - Difference Between Tax Provision at Statutory Federal Income Tax Rate and Tax Provision (Detail) - USD ($) $ in Thousands	12 Months Ended
Dec. 28, 2019	Dec. 29, 2018
Reconciliation Of Income Taxes [Line Items]
Income tax (benefit) at the federal statutory rate	$ 947	$ (756)
State income taxes, net of federal benefit	4	5
Research tax credits	(1,710)	(1,883)
Effect of foreign operations taxed at various rates	(397)	(254)
Effect of tax rate changes, permanent differences and adjustments of prior deferrals	3,685	4,142
Unrecognized tax benefits	1,519	(74)
Total	3,359	(7,176)
United States
Reconciliation Of Income Taxes [Line Items]
Change in valuation allowance	$ (689)	930
Foreign Tax Authority
Reconciliation Of Income Taxes [Line Items]
Change in valuation allowance		$ (9,286)

Reconciliation Of Income Taxes [Line Items]

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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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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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