CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 03, 2021	Jun. 27, 2020	Jul. 03, 2021	Jun. 27, 2020
Statement Of Income And Comprehensive Income [Abstract]
Net income (loss)	$ (6,126)	$ 1,524	$ (12,630)	$ 300
Other comprehensive income (loss), before tax:
Change in unrealized net gain on available-for-sale investments	(9)	51	(29)	53
Foreign currency translation gains (losses)	28	20	(40)	(75)
Other comprehensive income (loss), before tax	19	71	(69)	(22)
Income taxes related to items in other comprehensive income (loss)	0	0	0	0
Other comprehensive income (loss), net of tax	19	71	(69)	(22)
Comprehensive income(loss)	$ (6,107)	$ 1,595	$ (12,699)	$ 278