CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS Percentage	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Revenues
Lime and limestone operations (as a percent)	98.50%	97.90%	98.60%	97.80%
Natural gas (as a percent)	1.50%	2.10%	1.40%	2.20%
Total revenues (as a percent)	100.00%	100.00%	100.00%	100.00%
Cost of revenues:
Labor and other operating expenses (as a percent)	66.00%	66.40%	65.50%	67.00%
Depreciation, depletion and amortization (as a percent)	12.00%	12.00%	11.80%	12.40%
Total cost of revenues (as a percent)	78.00%	78.40%	77.30%	79.40%
Gross profit (as a percent)	22.00%	21.60%	22.70%	20.60%
Selling, general and administrative expenses (as a percent)	7.00%	7.40%	7.10%	7.70%
Operating profit (as a percent)	15.00%	14.20%	15.60%	12.90%
Other expenses (income):
Interest expense (as a percent)	0.20%	1.80%	0.20%	1.50%
Other (income) expense, net (as a percent)	(0.20%)	2.20%	(0.20%)	1.10%
Total other expense (income) (as a percent)	0.00%	4.00%	0.00%	2.60%
Income before income taxes (as a percent)	15.00%	10.20%	15.60%	10.30%
Income tax expense (as a percent)	3.80%	2.30%	3.90%	2.40%
Net income (as a percent)	11.20%	7.90%	11.70%	7.90%