Consolidated Statements Of Comprehensive Income - USD ($) shares in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Consolidated Statements Of Comprehensive Income [Abstract]
Net sales	$ 308,510,000	$ 323,317,000	$ 333,633,000
Cost of sales	236,585,000	247,434,000	246,399,000
Gross profit	71,925,000	75,883,000	87,234,000
Selling and general expenses	25,462,000	23,286,000	22,900,000
Intangibles amortization	83,000	2,167,000	2,630,000
Loss on divestiture, net		2,528,000
Operating profit	46,380,000	47,902,000	61,704,000
Other income	5,926,000	4,437,000	3,581,000
Earnings from continuing operations before provision for income taxes	52,306,000	52,339,000	65,285,000
Provision for income taxes from continuing operations	11,766,000	12,450,000	21,971,000
Earnings from continuing operations	40,540,000	39,889,000	43,314,000
Earnings from discontinued operations, net of tax	1,680,000	51,000	9,645,000
Net earnings	$ 42,220,000	$ 39,940,000	$ 52,959,000
Weighted average common shares outstanding:
Basic and diluted	7,027	7,005	6,989
Earnings per share, basic and diluted:
From continuing operations	$ 5.77	$ 5.69	$ 6.20
From discontinued operations	0.24	0.01	1.38
Net earnings per share	$ 6.01	$ 5.70	$ 7.58
Comprehensive income:
Net earnings	$ 42,220,000	$ 39,940,000	$ 52,959,000
Other comprehensive income (loss), net of tax:
Unrealized gain (loss) on available-for-sale securities	115,000	107,000	(39,000)
Comprehensive income	$ 42,335,000	$ 40,047,000	$ 52,920,000