Fair Value Measurements (Details 3) (USD $) In Thousands, unless otherwise specified								9 Months Ended
	Sep. 29, 2012	Dec. 31, 2011	Oct. 01, 2011	Sep. 29, 2012 Cost Basis	Oct. 01, 2011 Cost Basis	Sep. 29, 2012 Estimated Fair Value	Oct. 01, 2011 Estimated Fair Value	Sep. 29, 2012 Auction rate security	Oct. 01, 2011 Auction rate security
Level 3 reconciliation
Balance at the beginning of the period								$ 7,453	$ 6,775
Unrealized Gain in other comprehensive earnings								677	1,355
Balance at the end of the period								8,130	8,130
Industrial revenue development bonds, carrying amount, approximates fair value	$ 7,500	$ 7,500	$ 7,500	$ 7,500	$ 7,500	$ 7,500	$ 7,500