Condensed Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Income Statement [Abstract]
Sales of goods	$ 120,272	$ 103,058	$ 339,176	$ 318,414
Sales of services	46,822	28,434	123,262	76,640
Total net sales	167,094	131,492	462,438	395,054
Cost of goods sold	100,746	82,460	281,892	256,152
Cost of services sold	36,746	22,667	96,402	63,549
Total cost of sales	137,492	105,127	378,294	319,701
Gross profit	29,602	26,365	84,144	75,353
Selling and administrative expenses	21,662	20,218	65,488	60,023
Amortization expense	1,762	1,764	5,322	5,218
Interest expense	1,367	2,026	4,979	6,315
Interest income	(71)	(56)	(166)	(166)
Equity in loss (income) of nonconsolidated investments	4	(50)	7	5
Other (expense) income	153	(551)	(327)	(564)
Total expenses	24,877	23,351	75,303	70,831
Income before income taxes	4,725	3,014	8,841	4,522
Income tax (benefit) expense	(246)	(208)	952	698
Net income	$ 4,971	$ 3,222	$ 7,889	$ 3,824
Basic earnings per common share (usd per share)	$ 0.48	$ 0.31	$ 0.76	$ 0.37
Diluted earnings per common share (usd per share)	$ 0.47	$ 0.31	$ 0.75	$ 0.37