Property and Equipment (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Components of Property, Plant and Equipment
Land	$ 5,833	$ 5,088
Buildings and leasehold improvements	32,607	32,269
Machinery, equipment and rental tools	76,704	71,073
Equipment in progress	6,222	4,601
Furniture and fixtures	2,376	2,400
Property and equipment	137,809	129,388
Less accumulated depreciation	(55,417)	(50,274)
Property and equipment , net	82,392	79,114
Transportation equipment [Member]
Components of Property, Plant and Equipment
Property and equipment	6,599	6,340
Computer equipment and software [Member]
Components of Property, Plant and Equipment
Property and equipment	$ 7,468	$ 7,617