Consolidated Statement of Comprehensive Loss (unaudited) - USD ($) $ in Thousands	3 Months Ended
	Apr. 01, 2017	Apr. 02, 2016
Statement of Comprehensive Income [Abstract]
Net loss	$ (7,275)	$ (19,711)
Other comprehensive loss:
Unrealized loss related to marketable securities, net of tax	(43)	(28)
Reclassification adjustment for losses related to marketable securities included in other (expense) income, net of tax	170	2
Translation adjustment, net of tax	274	237
Comprehensive loss	$ (6,874)	$ (19,500)