UNAUDITED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE INCOME - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Income Statement [Abstract]
Contract revenues	$ 888,616	$ 708,114	$ 1,700,232	$ 1,344,738
Contract costs	798,489	627,252	1,525,713	1,183,391
Gross profit	90,127	80,862	174,519	161,347
Selling, general and administrative expenses	57,775	52,016	114,739	105,580
Amortization of intangible assets	1,229	3,253	2,455	6,020
Gain on sale of property and equipment	(1,315)	(652)	(2,539)	(1,400)
Income from operations	32,438	26,245	59,864	51,147
Other income (expense):
Interest income	193	6	514	14
Interest expense	(1,154)	(650)	(1,740)	(1,101)
Other income, net	120	2,277	30	2,262
Income before provision for income taxes	31,597	27,878	58,668	52,322
Income tax expense	9,324	8,194	13,232	11,950
Net income	$ 22,273	$ 19,684	$ 45,436	$ 40,372
Income per common share:
Basic (in dollars per share)	$ 1.33	$ 1.17	$ 2.73	$ 2.39
Diluted (in dollars per share)	$ 1.33	$ 1.15	$ 2.70	$ 2.36
Weighted average number of common shares and potential common shares outstanding:
Basic (in shares)	16,707	16,894	16,662	16,904
Diluted (in shares)	16,809	17,070	16,817	17,141
Net income	$ 22,273	$ 19,684	$ 45,436	$ 40,372
Other comprehensive income (loss):
Foreign currency translation adjustment	2,140	(3,477)	2,276	(1,826)
Other comprehensive income (loss)	2,140	(3,477)	2,276	(1,826)
Total comprehensive income	$ 24,413	$ 16,207	$ 47,712	$ 38,546