Inventories (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Lime and limestone inventories:
Raw materials	$ 5,815	$ 6,627
Finished goods	1,810	2,049
Total	7,625	8,676
Service parts inventories	6,147	6,052
Total inventories	$ 13,772	$ 14,728