CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE INCOME - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE INCOME
Net sales	$ 524,067	$ 474,927	$ 416,268
Cost of sales	369,177	331,841	282,294
Gross profit	154,890	143,086	133,974
Selling, general, and administrative expense	69,958	60,877	53,570
Intangibles amortization	11,472	11,401	10,596
Income from operations	73,460	70,808	69,808
Interest expense, net	(16,943)	(18,336)	(15,195)
Litigation proceeds		1,275	10,050
Other expense, net	(758)	(832)	(967)
Income before taxes	55,759	52,915	63,696
Income tax expense (benefit)	11,854	(2,409)	24,687
Net income	$ 43,905	$ 55,324	$ 39,009
Weighted average number of common shares outstanding:
Basic (in shares)	22,681,888	22,576,381	22,480,679
Diluted (in shares)	22,704,856	22,587,648	22,480,679
Earnings per common share:
Basic (in dollars per share)	$ 1.91	$ 2.42	$ 1.71
Diluted (in dollars per share)	1.89	2.40	1.70
Cash dividends declared per share (in dollars per share)	1.06	0.96	0.94
Cash dividends paid per share (in dollars per share)	$ 1.06	$ 0.96	$ 0.94