Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 28, 2019	Sep. 29, 2018	Sep. 28, 2019	Sep. 29, 2018
Consolidated Statements of Comprehensive Income [Abstract]
Net income	$ 14,319	$ 14,207	$ 49,098	$ 49,492
Available-for-sale marketable securities
Unrealized holding gains (losses) arising during period (Net of deferred taxes of $(67) and $68, respectively for the thirteen Weeks Ended and $(490) and $240, respectively for the thirty-nine Weeks Ended)	166	(175)	1,242	(620)
Reclassification adjustment for (gains) losses included in net income (Net of deferred taxes of $(16) and $0 , respectively for the thirteen Weeks Ended and $(16) and $15, respectively for the thirty-nine Weeks Ended)	(39)		(39)	39
Other comprehensive income gain (loss), net of tax	127	(175)	1,203	(581)
Comprehensive income, net of tax	$ 14,446	$ 14,032	$ 50,301	$ 48,911