Inventories (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Lime and limestone inventories:
Raw materials	$ 4,310	$ 3,540
Finished goods	1,727	2,107
Total	6,037	5,647
Service parts inventories	5,164	5,117
Total inventories	$ 11,201	$ 10,764