Interim Financial Information (Schedule Of Quarterly Financial Information) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Oct. 01, 2017	Jul. 02, 2017	Apr. 02, 2017	Dec. 31, 2016	Oct. 02, 2016	Jul. 03, 2016	Apr. 03, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Interim Financial Information [Abstract]
Net Sales	$ 115,604	$ 70,614	$ 74,561	$ 72,854	$ 131,914	$ 74,533	$ 69,516	$ 65,942	$ 333,633	$ 341,905	$ 355,649
Gross Profit	30,656	18,892	17,560	20,126	35,353	17,094	17,167	16,048	87,234	85,662	89,433
Earnings from continuing operations	16,062	8,338	8,941	9,973	19,702	7,767	7,936	6,510	43,314	41,915	42,162
Earnings (loss) from discontinued operations, net of tax	698	(6)	771	8,182	1,073	537	338	701	9,645	2,649	(1,666)
Net earnings	$ 16,760	$ 8,332	$ 9,712	$ 18,155	$ 20,775	$ 8,304	$ 8,274	$ 7,211	$ 52,959	$ 44,564	$ 40,496
Earnings from continuing operations per share, basic and diluted	$ 2.30	$ 1.19	$ 1.28	$ 1.43	$ 2.82	$ 1.11	$ 1.14	$ 0.94	$ 6.20	$ 6.01	$ 6.07
Earnings (loss) from discontinued operations per share, net of tax, basic and diluted	0.10		0.11	1.17	0.15	0.08	0.05	0.10	1.38	0.38	(0.24)
Net earnings per share	$ 2.40	$ 1.19	$ 1.39	$ 2.60	$ 2.97	$ 1.19	$ 1.19	$ 1.04	$ 7.58	$ 6.39	$ 5.83