Summary of Significant Accounting Policies (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Supplemental cash flow information
Interest	$ 1,495us-gaap_InterestPaid	$ 1,746us-gaap_InterestPaid	$ 2,069us-gaap_InterestPaid
Income taxes	5,870us-gaap_IncomeTaxesPaidNet	3,750us-gaap_IncomeTaxesPaidNet	3,000us-gaap_IncomeTaxesPaidNet
Revenue Recognition
External freight billed to customers included in revenue	27,055us-gaap_ShippingAndHandlingRevenue	25,536us-gaap_ShippingAndHandlingRevenue	26,675us-gaap_ShippingAndHandlingRevenue
Additions and write-offs to the company's allowance for doubtful accounts
Beginning balance	238	525
Additions	148us-gaap_ProvisionForDoubtfulAccounts	69us-gaap_ProvisionForDoubtfulAccounts
Write-offs	(36)	(356)
Ending balance	350	238	525
Lime and limestone inventories:
Raw materials	5,693	6,203
Finished goods	2,283	2,284
Total	7,976	8,487
Service parts inventories	5,460us-gaap_OtherInventoryNetOfReserves	5,201us-gaap_OtherInventoryNetOfReserves
Total inventories	13,436us-gaap_InventoryNet	13,688us-gaap_InventoryNet
Three month LIBOR
Fair Values of Financial Instruments
Variable rate basis	three-month LIBOR
Recurring \| Fair value \| Cash flows approach
Fair Values of Financial Instruments
Interest rate swap liabilities	(661)	(1,533)
Recurring \| Significant Other Observable Inputs (Level 2) \| Cash flows approach
Fair Values of Financial Instruments
Interest rate swap liabilities	$ (661)	$ (1,533)

A valuation allowance for trade and other receivables due to an Entity within one year (or the normal operating cycle, whichever is longer) that are expected to be uncollectible.

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