Inventories, Net (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Lime and limestone inventories:
Raw materials	$ 4,068	$ 5,105
Finished goods	2,027	2,266
Total	6,095	7,371
Service parts inventories	6,162	6,175
Total inventories	$ 12,257	$ 13,546