Reportable Segments (Details) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019 USD ($)	Sep. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Sep. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2019 USD ($) segment	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Business segments
Number of business segments | segment									1
Revenues	$ 37,965	$ 43,559	$ 38,954	$ 37,799	$ 34,634	$ 35,272	$ 39,242	$ 35,287	$ 158,277	$ 144,435	$ 144,844
Depreciation, depletion and amortization									17,394	17,391	16,340
Gross profit (loss)	9,773	13,483	9,727	8,693	6,616	7,196	9,637	7,037	41,676	30,486	34,380
Operating profit									29,246	20,002	24,227
Assets	247,037				244,671				247,037	244,671	228,446
Capital expenditures									27,100	53,762	21,337
Impairment of long-lived assets									930
Unallocated corporate assets and cash items
Business segments
Assets	61,380				75,489				61,380	75,489	95,096
Lime and limestone operations
Business segments
Depreciation, depletion and amortization									16,432	16,741	15,694
Gross profit (loss)									42,043	29,482	33,652
Operating profit									30,543	18,998	23,499
Assets	185,657				169,182				185,657	169,182	133,350
Capital expenditures									27,100	53,762	21,335
Other
Business segments
Depreciation, depletion and amortization									962	650	646
Gross profit (loss)									(367)	1,004	728
Operating profit									(1,297)	1,004	728
Capital expenditures											2
Lime and limestone operations
Business segments
Revenues	37,670	43,265	38,581	37,465	33,938	34,713	38,557	34,714
Lime and limestone operations | Lime and limestone operations
Business segments
Revenues									156,981	141,922	142,612
Other
Business segments
Revenues	$ 295	$ 294	$ 373	$ 334	$ 696	$ 559	$ 685	$ 573
Other | Other
Business segments
Revenues									$ 1,296	$ 2,513	$ 2,232