CONDENSED CONSOLIDATED STATEMENTS OF INCOME (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Income Statement [Abstract]
NET SALES	$ 159,160	$ 148,933
COSTS OF OPERATIONS	140,733	133,538
GROSS PROFIT	18,427	15,395
OPERATING EXPENSES:
Selling, general and administrative expenses	9,589	9,044
NON-OPERATING (INCOME) EXPENSES:
Interest expense, net	420	378
Other (income) expense, net	(915)	(14)
Total expenses, net	9,094	9,408
INCOME BEFORE INCOME TAXES	9,333	5,987
INCOME TAX PROVISION	2,663	2,148
NET INCOME	$ 6,670	$ 3,839
BASIC INCOME PER COMMON SHARE (in dollars per share)	$ 0.59	$ 0.34
DILUTED INCOME PER COMMON SHARE (in dollars per share)	0.59	0.34
CASH DIVIDENDS DECLARED PER COMMON SHARE (in dollars per share)	$ 0.18	$ 0.18
WEIGHTED AVERAGE SHARES OUTSTANDING:
Basic (in shares)	11,384	11,350
Diluted (in shares)	11,393	11,380