Condensed Unaudited Consolidated Statements of Comprehensive Loss (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 28, 2014	Sep. 29, 2013	Sep. 28, 2014	Sep. 29, 2013
Statement of Comprehensive Income [Abstract]
Net loss	$ (3,930)	$ (2,262)	$ (8,937)	$ (9,087)
Other comprehensive loss, net of tax:
Unrealized loss on available-for-sale investments	0	0	0	11
Total comprehensive loss	$ (3,930)	$ (2,262)	$ (8,937)	$ (9,076)