Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 26, 2015	Sep. 27, 2014	Sep. 26, 2015	Sep. 27, 2014
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 818	$ (28,662)	$ 4,718	$ (26,479)
Other comprehensive income (loss):
Change in foreign currency translation adjustment	(235)	(1,637)	(1,980)	(1,252)
Net change on unrealized gains on available-for-sale investments	17	(15)	42	(7)
Other comprehensive income (loss)	(218)	(1,652)	(1,938)	(1,259)
Comprehensive income (loss)	$ 600	$ (30,314)	$ 2,780	$ (27,738)