Fair Value Measurements (Details 3) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jul. 02, 2011	Jun. 30, 2012	Dec. 31, 2011
Level 3 reconciliation
Industrial revenue development bonds, carrying amount, approximates fair value	$ 7,500	$ 7,500	$ 7,500
Equity method investment	4,751	3,270	3,935
Cost Basis
Level 3 reconciliation
Industrial revenue development bonds, carrying amount, approximates fair value	7,500	7,500
Estimated Fair Value
Level 3 reconciliation
Industrial revenue development bonds, carrying amount, approximates fair value	7,500	7,500
Auction rate security
Level 3 reconciliation
Balance at the beginning of the period	6,775	7,453	7,453
Unrealized Gain in other comprehensive earnings	1,355
Balance at the end of the period	$ 8,130	$ 7,453	$ 7,453