Consolidated Statements of Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Revenues
Revenues	$ 236,150	$ 189,255	$ 160,704
Cost of revenues
Labor and other operating expenses	143,887	109,365	93,738
Depreciation, depletion and amortization	21,921	20,630	19,379
Total cost of revenues	165,808	129,995	113,117
Gross profit	70,342	59,260	47,587
Selling, general and administrative expenses	15,559	12,843	12,168
Impairment of long-lived assets			1,550
Operating profit	54,783	46,417	33,869
Other expense (income)
Interest expense	254	250	248
Interest and other income, net	(2,033)	(351)	(451)
Total other expense (income)	(1,779)	(101)	(203)
Income before income tax expense	56,562	46,518	34,072
Income tax expense	11,133	9,473	5,849
Net income	$ 45,429	$ 37,045	$ 28,223
Net income per share of common stock
Basic (in dollars per share)	$ 8.01	$ 6.55	$ 5.01
Diluted (in dollars per share)	$ 8.00	$ 6.54	$ 5.00