CONDENSED CONSOLIDATED STATEMENTS OF INCOME (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Income Statement [Abstract]
NET SALES	$ 153,089	$ 156,113	$ 302,022	$ 304,928
COSTS OF OPERATIONS	135,486	137,076	269,024	272,921
GROSS PROFIT	17,603	19,037	32,998	32,007
OPERATING EXPENSES:
Selling, general and administrative expenses	9,066	8,318	18,110	16,328
Interest expense, net	315	259	693	457
Other (income) expense, net	(470)	128	(484)	(213)
Total operating expenses	8,911	8,705	18,319	16,572
INCOME BEFORE INCOME TAXES	8,692	10,332	14,679	15,435
INCOME TAX PROVISION	3,267	3,745	5,415	5,488
NET INCOME	$ 5,425	$ 6,587	$ 9,264	$ 9,947
BASIC INCOME PER COMMON SHARE	$ 0.48	$ 0.58	$ 0.82	$ 0.88
DILUTED INCOME PER COMMON SHARE	0.48	0.58	0.81	0.88
CASH DIVIDENDS DECLARED PER COMMON SHARE	$ 0.18	$ 0.17	$ 0.36	$ 0.34
WEIGHTED AVERAGE SHARES OUTSTANDING:
Basic	11,365	11,346	11,357	11,346
Diluted	11,383	11,374	11,381	11,373