Summary of Significant Accounting Policies - Additional Disclosures (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Additions and write-offs to the company's allowance for doubtful accounts
Beginning balance	$ 398	$ 361
Additions	66	60
Adjustments for expected credit loss factors	(14)
Write-offs		(23)
Ending balance	450	398	$ 361
Lime and limestone inventories:
Raw materials	3,232	4,279
Finished goods	2,677	2,866
Total	5,909	7,145
Service parts inventories	9,207	8,065
Total inventories	15,116	15,210
Supplemental cash flow information
Interest	151	152	150
Income taxes	9,483	975	445
Revenue Recognition
External freight billed to customers included in revenue	$ 34,307	$ 28,373	$ 28,397