Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 26, 2015	Dec. 27, 2014
Statement Of Income And Comprehensive Income [Abstract]
Net income (loss)	$ 44,035	$ 2,905	$ (31,118)
Other comprehensive income (loss):
Change in foreign currency translation adjustment	(869)	(2,344)	(3,239)
Employee benefit plan adjustment	(17)	(76)	(106)
Net change on unrealized gains (losses) on available-for-sale investments	42	(13)	(36)
Other comprehensive loss	(844)	(2,433)	(3,381)
Comprehensive income (loss)	$ 43,191	$ 472	$ (34,499)