Property and Equipment (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Components of Property, Plant and Equipment
Land	$ 7,140	$ 6,780
Buildings and leasehold improvements	34,332	33,765
Machinery, equipment and rental tools	83,997	80,731
Equipment in progress	4,467	7,299
Furniture and fixtures	2,658	2,528
Property and equipment	150,622	145,274
Less accumulated depreciation	(63,626)	(59,163)
Property and equipment , net	86,996	86,111
Transportation equipment [Member]
Components of Property, Plant and Equipment
Property and equipment	7,509	6,566
Computer equipment and software [Member]
Components of Property, Plant and Equipment
Property and equipment	$ 10,519	$ 7,605