Income Taxes (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Taxes
Current income tax expense	$ 5,282	$ 3,240	$ 3,547
Deferred income tax expense	1,273	1,793	2,131
Income tax expense	6,555	5,033	5,678
Amount
Income taxes computed at the federal statutory rate	9,073	6,942	7,735
(Reduction) increase in taxes resulting from:
Statutory depletion in excess of cost depletion	(2,139)	(1,965)	(2,048)
Manufacturing deduction	(574)	(299)	(335)
State income taxes, net of federal income tax benefit	104	132	331
Other	91	223	(5)
Income tax expense	6,555	5,033	5,678
Percent of Pretax Income
Income taxes computed at the federal statutory rate (as a percent)	35.00%	35.00%	35.00%
(Reduction) increase in taxes resulting from (as a percent):
Statutory depletion in excess of cost depletion (as a percent)	(8.20%)	(9.90%)	(9.30%)
Manufacturing deduction (as a percent)	(2.20%)	(1.50%)	(1.50%)
State income taxes, net of federal income tax benefit (as a percent)	0.40%	0.70%	1.50%
Other (as a percent)	0.30%	1.10%	0.00%
Income tax expense (as a percent)	25.30%	25.40%	25.70%
Deferred tax liabilities
Lime and limestone property, plant and equipment	20,089	20,614
Natural gas interests drilling costs and equipment	3,387	3,680
Other	292	344
Total	23,768	24,638
Deferred tax assets
Alternative minimum tax credit carry forwards	3,887	5,866
Minimum pension liability	346	299
Fair value liability of interest rate hedges	240	557
Other	470	635
Total	4,943	7,357
Deferred Tax Liabilities, Net, Total	18,825	17,281
Current income taxes:
Prepaid expenses and other current assets	881	203
Deferred income taxes:
Prepaid expenses and other current assets	434	518
Deferred tax liabilities, net	19,259	17,799
Federal
Operating loss carry forwards
Net operating loss	$ 0