Consolidated Statements of Comprehensive Income (Parenthetical) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 29, 2012	Sep. 24, 2011	Sep. 29, 2012	Sep. 24, 2011
Consolidated Statements of Comprehensive Income
Unrealized holding gains arising during period, tax	$ 180	$ 72	$ 697	$ 554
Reclassification adjustment for gains included in net income, tax		$ 105	$ 314	$ 528