Inventories (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Lime and limestone inventories:
Raw materials	$ 6,144	$ 5,693
Finished goods	1,966	2,283
Total	8,110	7,976
Service parts inventories	5,527	5,460
Total inventories	$ 13,637	$ 13,436