CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Revenues
Total revenues	$ 35,272	$ 36,934	$ 109,801	$ 109,605
Cost of revenues
Labor and other operating expenses	23,687	23,142	73,077	70,447
Depreciation, depletion and amortization	4,389	4,240	12,854	12,530
Total cost of revenues	28,076	27,382	85,931	82,977
Gross profit	7,196	9,552	23,870	26,628
Selling, general and administrative expenses	2,790	2,657	7,856	7,595
Operating profit	4,406	6,895	16,014	19,033
Other (income) expense
Interest expense	66	56	191	174
Interest and other income, net	(495)	(261)	(1,307)	(665)
Total other (income) expense	(429)	(205)	(1,116)	(491)
Income before income tax expense	4,835	7,100	17,130	19,524
Income tax expense	281	1,433	1,676	3,959
Net income	$ 4,554	$ 5,667	$ 15,454	$ 15,565
Net income per share of common stock
Basic (in dollars per share)	$ 0.81	$ 1.02	$ 2.76	$ 2.79
Diluted (in dollars per share)	0.81	1.01	2.76	2.79
Cash dividends per share of common stock (in dollars per share)	$ 0.135	$ 0.135	$ 0.405	$ 0.405
Lime and limestone operations
Revenues
Total revenues	$ 34,713	$ 36,428	$ 107,984	$ 107,910
Natural gas interests
Revenues
Total revenues	$ 559	$ 506	$ 1,817	$ 1,695