Consolidated Statements of Comprehensive Income (Parenthetical) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 25, 2011	Jun. 30, 2012	Jun. 25, 2011
Consolidated Statements of Comprehensive Income
Unrealized holding gains arising during period, tax	$ 603	$ 355	$ 517	$ 482
Reclassification adjustment for gains included in net income, tax	$ 313	$ 165	$ 314	$ 423