Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 26, 2015	Dec. 27, 2014
Consolidated Statements of Comprehensive Income [Abstract]
Net income	$ 87,162	$ 59,330	$ 54,381
Other comprehensive income (loss) by component, net of tax:
Available-for-sale marketable securities Unrealized holding gains (losses) arising during period (Net of deferred taxes of $239, $37 and $644, respectively)	348	(52)	927
Reclassification adjustment for gains included in net income (Net of deferred taxes of $180, $11 and $26, respectively)	(257)	(16)	(37)
Other comprehensive income (loss), net of tax	91	(68)	890
Comprehensive income, net of tax	$ 87,253	$ 59,262	$ 55,271