CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 26, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement Of Income And Comprehensive Income [Abstract]
Net income	$ 31,025	$ 1,910	$ 45,096
Other comprehensive income (loss), net of tax:
Change in net unrealized gains (losses) on available-for-sale marketable securities	123	(44)	136
Change in currency translation adjustments	5,043	709	(194)
Total other comprehensive income (loss), net of tax	5,166	665	(58)
Total comprehensive income	$ 36,191	$ 2,575	$ 45,038