CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Revenues
Total revenues	$ 35,287	$ 36,153
Cost of revenues
Labor and other operating expenses	24,073	23,679
Depreciation, depletion and amortization	4,177	4,236
Total cost of revenues	28,250	27,915
Gross profit	7,037	8,238
Selling, general and administrative expenses	2,501	2,420
Operating profit	4,536	5,818
Other (income) expenses
Interest expense	62	59
Interest and other income, net	(353)	(179)
Total other (income) expense	(291)	(120)
Income before income tax expense	4,827	5,938
Income tax expense	565	1,318
Net income	$ 4,262	$ 4,620
Net income per share of common stock
Basic (in dollars per share)	$ 0.76	$ 0.83
Diluted (in dollars per share)	0.76	0.83
Cash dividends per share of common stock (in dollars per share)	$ 0.135	$ 0.135
Lime and limestone operations
Revenues
Total revenues	$ 34,714	$ 35,517
Natural gas interests
Revenues
Total revenues	$ 573	$ 636