Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Amount
Income taxes computed at the federal statutory rate	$ 6,489	$ 4,529	$ 8,730
(Reduction) increase in taxes resulting from:
Benefit of reduced federal income tax rates			(7,447)
Statutory depletion in excess of cost depletion	(1,200)	(1,199)	(2,004)
Research and development tax credit	(1,155)	(1,775)	(1,433)
Manufacturing deduction			(674)
State income taxes, net of federal income tax benefit	155	178	235
Other	555	150	388
Income tax expense (benefit)	$ 4,844	$ 1,883	$ (2,205)
Percent of Pretax Income
Income taxes computed at the federal statutory rate (as a percent)	21.00%	21.00%	35.00%
(Reduction) increase in taxes resulting from (as a percent):
Benefit of reduced federal income tax rates (as a percent)			(29.90%)
Statutory depletion in excess of cost depletion (as a percent)	(3.90%)	(5.60%)	(8.00%)
Research and development tax credit (as a percent)	(3.70%)	(8.20%)	(5.70%)
Manufacturing deduction (as a percent)			(2.70%)
State income taxes, net of federal income tax benefit (as a percent)	0.50%	0.80%	0.90%
Other (as a percent)	1.80%	0.70%	1.60%
Income tax expense (benefit) (as a percent)	15.70%	8.70%	(8.80%)
Deferred tax liabilities
Lime and limestone property, plant and equipment	$ 16,928	$ 11,219
Operating lease right-of-use assets	735
Natural gas interests drilling costs and equipment	1,040	1,475
Total	18,703	12,694
Deferred tax assets
Fair value liability of foreign exchange hedges		3
Operating lease liabilities	728
Other	757	326
Total	1,485	329
Deferred tax liabilities, net, Total	17,218	12,365
Current income taxes:
Prepaid expenses and other current assets	416
Accrued expenses		54
Current income tax (benefit) expense	(4)	1,863	$ 5,407
Deferred income tax expense (benefit)	4,848	20	(7,612)
Income tax expense (benefit)	4,844	$ 1,883	$ (2,205)
Federal
Operating loss carry forwards
Net operating loss carryforwards	$ 0