Summary of Significant Accounting Policies - Changes in Accumulated Other Comprehensive Income by Component (Detail)- - USD ($) $ in Thousands	12 Months Ended
	Dec. 28, 2019	Dec. 29, 2018
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	$ 89,624	$ 82,663
Other comprehensive income (loss) before reclassification	46	(112)
Other comprehensive income (loss), net of tax	46	(112)
Ending balance	95,793	89,624
Foreign currency
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	405	535
Other comprehensive income (loss) before reclassification	(24)	(130)
Other comprehensive income (loss), net of tax	(24)	(130)
Ending balance	381	405
Unrealized holding gains (losses) on available- for-sale investments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(27)	(45)
Other comprehensive income (loss) before reclassification	70	18
Other comprehensive income (loss), net of tax	70	18
Ending balance	43	(27)
Accumulated Other Comprehensive Income
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	378	490
Ending balance	$ 424	$ 378