Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 29, 2018	Dec. 30, 2017	Dec. 31, 2016
Statement Of Income And Comprehensive Income [Abstract]
Net income (loss)	$ 57,648	$ 30,202	$ 44,035
Other comprehensive income (loss):
Change in foreign currency translation adjustment	(482)	4,170	(869)
Employee benefit plan adjustment	(259)	(160)	(17)
Net change on unrealized gains (losses) on available-for-sale investments	308	(88)	42
Other comprehensive income (loss):	(433)	3,922	(844)
Comprehensive income (loss)	$ 57,215	$ 34,124	$ 43,191