Equity - Changes in Accumulated Other Comprehensive Income by Component (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 28, 2020	Mar. 30, 2019
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	$ 95,793	$ 89,624
Other comprehensive income (loss), net of tax	(93)	106
Ending balance	95,669	89,087
Foreign currency
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	381	405
Other comprehensive income (loss) before reclassification	(95)	61
Other comprehensive income (loss), net of tax	(95)	61
Ending balance	286	466
Unrealized holding gains (losses) on available- for-sale investments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	43	(27)
Other comprehensive income (loss) before reclassification	2	45
Other comprehensive income (loss), net of tax	2	45
Ending balance	45	18
Accumulated Other Comprehensive Income
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	424	378
Other comprehensive income (loss) before reclassification	(93)	106
Other comprehensive income (loss), net of tax	(93)	106
Ending balance	$ 331	$ 484