CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) (unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 30, 2019	Mar. 31, 2018
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 7,408	$ (5,952)
Other comprehensive income (loss):
Unrealized gain (loss) related to marketable securities, net of tax	42	(7)
Reclassification adjustment for gains related to marketable securities included in Other income, net of tax	(53)	(1)
Translation adjustment, net of tax	47	589
Comprehensive income (loss)	$ 7,444	$ (5,371)