CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS Percentage	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Revenues
Lime and limestone operations (as a percent)	95.80%	95.20%	95.60%	94.60%
Natural gas interests (as a percent)	4.20%	4.80%	4.40%	5.40%
Total revenues (as a percent)	100.00%	100.00%	100.00%	100.00%
Cost of revenues:
Labor and other operating expenses (as a percent)	64.30%	67.00%	66.30%	65.80%
Depreciation, depletion and amortization (as a percent)	10.20%	10.10%	10.90%	10.00%
Total cost of revenues (as a percent)	74.50%	77.10%	77.20%	75.80%
Gross profit (as a percent)	25.50%	22.90%	22.80%	24.20%
Selling, general and administrative expenses (as a percent)	6.50%	6.40%	6.70%	6.30%
Operating profit (as a percent)	19.00%	16.50%	16.10%	17.90%
Other expense (income):
Interest expense (as a percent)	1.40%	1.50%	1.40%	1.60%
Other, net (as a percent)	(0.10%)	(0.20%)	(0.20%)	(0.10%)
Total other expense (income) (as a percent)	1.30%	1.30%	1.20%	1.50%
Income before income taxes (as a percent)	17.70%	15.20%	14.90%	16.40%
Income tax expense (as a percent)	4.60%	4.10%	3.80%	4.40%
Net income (as a percent)	13.10%	11.10%	11.10%	12.00%