CONSOLIDATED STATEMENTS OF INCOME - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Statement [Abstract]
Net sales	$ 114,537	$ 124,243	$ 118,217
Cost of sales	81,689	85,280	79,946
Gross margin	32,848	38,963	38,271
Selling, general and administrative expense	21,031	21,297	20,460
Operating income	11,817	17,666	17,811
Interest income	1,680	3,270	2,664
Income before income taxes	13,497	20,936	20,475
Provision for income taxes	3,174	4,938	5,150
Net income	$ 10,323	$ 15,998	$ 15,325
Basic and diluted earnings per common share	$ 0.83	$ 1.29	$ 1.23
Basic and diluted weighted average shares outstanding	12,448	12,440	12,432