Condensed Consolidated Statements of Comprehensive Income (Parenthetical) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 29, 2014	Jun. 30, 2013	Jun. 29, 2014	Jun. 30, 2013
Net unrealized gains on marketable securities arising during period, tax	$ 558	$ (841)	$ 1,242	$ (726)
Reclassification adjustment for net gains included in net income, tax	(141)	(39)	(243)	(122)
Amortization of prior service benefit, tax	$ (42)	$ (40)	$ (85)	$ (79)