Interim Financial Information (Schedule Of Quarterly Financial Information) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jul. 01, 2012	Apr. 01, 2012	Dec. 31, 2011	Oct. 02, 2011	Jul. 03, 2011	Apr. 03, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Interim Financial Information [Abstract]
Net Sales	$ 141,790	$ 116,813	$ 117,114	$ 96,773	$ 119,006	$ 104,861	$ 98,268	$ 108,886	$ 472,490	$ 431,021	$ 479,000
Gross Profit	32,010	22,907	19,594	20,352	27,483	23,657	20,665	21,954	94,863	93,759	113,574
Net Earnings	$ 11,427	$ 9,401	$ 8,703	$ 9,344	$ 13,402	$ 12,386	$ 10,817	$ 11,363	$ 38,875	$ 47,968	$ 63,531
Earnings Per Share (Basic)	$ 1.66	$ 1.36	$ 1.26	$ 1.36	$ 1.96	$ 1.80	$ 1.57	$ 1.65	$ 5.64	$ 6.98	$ 9.26
Earnings Per Share (Diluted)	$ 1.66	$ 1.36	$ 1.26	$ 1.36	$ 1.96	$ 1.80	$ 1.57	$ 1.65	$ 5.64	$ 6.98	$ 9.26