CONDENSED CONSOLIDATED STATEMENTS OF INCOME - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
CONDENSED CONSOLIDATED STATEMENTS OF INCOME
NET SALES	$ 222,346	$ 176,888	$ 419,559	$ 336,048
COSTS OF OPERATIONS	197,133	155,609	371,749	296,342
GROSS PROFIT	25,213	21,279	47,810	39,706
OPERATING EXPENSES:
Selling, general and administrative expenses	10,968	9,678	21,183	19,267
NON-OPERATING (INCOME) EXPENSES:
Interest expense, net	721	484	1,389	904
Other (income) expense, net	57	627	311	(288)
Total expense, net	11,746	10,789	22,883	19,883
INCOME BEFORE INCOME TAXES	13,467	10,490	24,927	19,823
INCOME TAX PROVISION	2,784	2,890	5,584	5,553
NET INCOME	$ 10,683	$ 7,600	$ 19,343	$ 14,270
BASIC INCOME PER COMMON SHARE (in dollars per share)	$ 0.94	$ 0.67	$ 1.70	$ 1.25
DILUTED INCOME PER COMMON SHARE (in dollars per share)	0.94	0.67	1.70	1.25
CASH DIVIDENDS DECLARED PER COMMON SHARE (in dollars per share)	$ 0.18	$ 0.18	$ 0.36	$ 0.36
WEIGHTED AVERAGE SHARES OUTSTANDING:
Basic (in shares)	11,400	11,384	11,400	11,384
Diluted (in shares)	11,400	11,393	11,400	11,393