Condensed Consolidated Statements of Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Income Statement [Abstract]
Sales	$ 92,560	$ 90,501	$ 191,642	$ 179,597
Cost of sales	71,858	70,979	147,729	143,415
Gross profit	20,702	19,522	43,913	36,182
Selling, general and administrative expenses	9,364	8,648	18,867	16,795
Operating income	11,338	10,874	25,046	19,387
Interest expense, net and other	(298)	(321)	(940)	(573)
Income before income taxes	11,040	10,553	24,106	18,814
Income tax expense	2,550	2,642	5,774	1,183
Net income	8,490	7,911	18,332	17,631
Income attributable to participating securities	57	51	123	117
Net income attributable to common shareholders and used in earnings per share calculation	$ 8,433	$ 7,860	$ 18,209	$ 17,514
Share information:
Basic and diluted weighted average common shares (in shares)	16,899,079	17,021,599	16,956,502	16,994,864
Basic and diluted earnings per common share (in dollars per share)	$ 0.50	$ 0.46	$ 1.07	$ 1.03