Consolidated Statements of Income (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Revenues
Lime and limestone operations	$ 144,567	$ 128,003	$ 131,404
Natural gas interests	5,274	5,762	7,121
Total revenues	149,841	133,765	138,525
Labor and other operating expenses
Lime and limestone operations	96,798	86,754	88,346
Natural gas interests	1,546	1,920	1,891
Depreciation, depletion and amortization	14,706	14,291	14,850
Total cost of revenues	113,050	102,965	105,087
Gross profit	36,791	30,800	33,438
Selling, general and administrative expenses, including depreciation and amortization expense of $197, $207 and $194 in 2014, 2013 and 2012, respectively	9,469	9,149	9,193
Operating profit	27,322	21,651	24,245
Other expense (income):
Interest expense	1,529	1,852	2,163
Other, net	(129)	(34)	(19)
Total other expense (income)	1,400	1,818	2,144
Income before income taxes	25,922	19,833	22,101
Income tax expense	6,555	5,033	5,678
Net income	$ 19,367	$ 14,800	$ 16,423
Net income per share of common stock:
Basic (in dollars per share)	$ 3.47	$ 2.66	$ 2.88
Diluted (in dollars per share)	$ 3.47	$ 2.66	$ 2.87
Cash dividends per share of common stock (in dollars per share)	$ 0.50