Consolidated Statements Of Comprehensive Income - USD ($) shares in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Consolidated Statements Of Comprehensive Income [Abstract]
Net sales	$ 341,905,000	$ 355,649,000	$ 347,198,000
Cost of sales	256,243,000	266,216,000	265,892,000
Gross profit	85,662,000	89,433,000	81,306,000
Selling and general expenses	22,429,000	21,735,000	21,422,000
Intangibles amortization	721,000	5,173,000	11,991,000
Impairment of finite lived intangible assets			2,063,000
Operating profit	62,512,000	62,525,000	45,830,000
Other income, principally interest	810,000	397,000	367,000
Earnings from continuing operations before provision for income taxes	63,322,000	62,922,000	46,197,000
Provision for income taxes	21,407,000	20,760,000	15,445,000
Earnings from continuing operations	41,915,000	42,162,000	30,752,000
Earnings (loss) from discontinued operations, net of tax	2,649,000	(1,666,000)	(4,275,000)
Net earnings	$ 44,564,000	$ 40,496,000	$ 26,477,000
Weighted average shares outstanding:
Basic and diluted	6,970	6,951	6,930
Earnings (loss) per share, basic and diluted:
From continuing operations	$ 6.01	$ 6.07	$ 4.44
From discontinued operations	0.38	(0.24)	(0.62)
Net earnings per share	$ 6.39	$ 5.83	$ 3.82
Other comprehensive loss, net of tax:
Unrealized loss on available-for-sale securities	$ 38,000	$ 6,000	$ 11,000
Comprehensive income	$ 44,526,000	$ 40,490,000	$ 26,466,000