CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) (unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 29, 2019	Jun. 30, 2018	Jun. 29, 2019	Jun. 30, 2018
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 8,559	$ (20,223)	$ 15,967	$ (26,175)
Other comprehensive income (loss):
Unrealized gain related to marketable securities, net of tax	0	9	42	2
Reclassification adjustment for gains related to marketable securities included in Other (expense) income, net of tax	0	0	(53)	(1)
Translation adjustment, net of tax	39	(1,129)	86	(540)
Comprehensive income (loss)	$ 8,598	$ (21,343)	$ 16,042	$ (26,714)