Reclassifications Out of Accumulated Other Comprehensive Income (Loss) to Statements of Operations (Parenthetical) (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 03, 2021	Sep. 27, 2020	Oct. 03, 2021	Sep. 27, 2020
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassifications, tax	$ 65	$ 194	$ 188	$ 616
Unrealized (Losses) Gains on Marketable Securities
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassifications, tax	65	194	186	615
Amortization of Prior Service Credit
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassifications, tax	$ 0	$ 0	$ 2	$ 1