CONDENSED CONSOLIDATED STATEMENTS OF INCOME - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
CONDENSED CONSOLIDATED STATEMENTS OF INCOME
NET SALES	$ 195,467	$ 195,690	$ 615,026	$ 531,738
COSTS OF OPERATIONS	173,721	174,214	545,470	470,556
GROSS PROFIT	21,746	21,476	69,556	61,182
OPERATING EXPENSES:
Selling, general and administrative expenses	10,453	9,450	31,636	28,717
NON-OPERATING (INCOME) EXPENSES:
Interest expense, net	424	525	1,813	1,429
Other (income) expense, net	231	76	542	(212)
Total expense, net	11,108	10,051	33,991	29,934
INCOME BEFORE INCOME TAXES	10,638	11,425	35,565	31,248
INCOME TAX PROVISION	2,562	2,748	8,146	8,301
NET INCOME	$ 8,076	$ 8,677	$ 27,419	$ 22,947
BASIC INCOME PER COMMON SHARE (in dollars per share)	$ 0.71	$ 0.76	$ 2.41	$ 2.02
DILUTED INCOME PER COMMON SHARE (in dollars per share)	0.71	0.76	2.41	2.01
CASH DIVIDENDS DECLARED PER COMMON SHARE (in dollars per share)	$ 0.18	$ 0.18	$ 0.54	$ 0.54
WEIGHTED AVERAGE SHARES OUTSTANDING:
Basic (in shares)	11,400	11,389	11,400	11,386
Diluted (in shares)	11,400	11,393	11,400	11,393