Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended
	Apr. 01, 2017	Mar. 26, 2016
Consolidated Statements of Comprehensive Income [Abstract]
Net income	$ 11,836	$ 20,129
Other comprehensive income (loss) by component, net of tax:
Available-for-sale marketable securities Unrealized holding gains arising during period (Net of deferred taxes of $11 and $570, respectively)	64	816
Reclassification adjustment for gains included in net income (Net of deferred taxes of $0 and $111, respectively)		(158)
Other comprehensive income, net of tax	64	658
Comprehensive income, net of tax	$ 11,900	$ 20,787