Property and Equipment (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Components of Property, Plant and Equipment
Land	$ 7,122us-gaap_Land	$ 6,780us-gaap_Land
Buildings and leasehold improvements	33,933us-gaap_BuildingsAndImprovementsGross	33,765us-gaap_BuildingsAndImprovementsGross
Machinery, equipment and rental tools	85,108us-gaap_MachineryAndEquipmentGross	80,731us-gaap_MachineryAndEquipmentGross
Equipment in progress	4,429us-gaap_ConstructionInProgressGross	7,299us-gaap_ConstructionInProgressGross
Furniture and fixtures	2,619us-gaap_FurnitureAndFixturesGross	2,528us-gaap_FurnitureAndFixturesGross
Property and equipment	150,492us-gaap_PropertyPlantAndEquipmentGross	145,274us-gaap_PropertyPlantAndEquipmentGross
Less accumulated depreciation	(62,253)	(59,163)
Property and equipment, net	88,239us-gaap_PropertyPlantAndEquipmentNet	86,111us-gaap_PropertyPlantAndEquipmentNet
Transportation equipment [Member]
Components of Property, Plant and Equipment
Property and equipment	6,959	6,566
Computer equipment and software [Member]
Components of Property, Plant and Equipment
Property and equipment	$ 10,322	$ 7,605

Amount of accumulated depreciation, depletion and amortization for physical assets used in the normal conduct of business to produce goods and services.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 360

-SubTopic 10

-Section 50

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- Definition

Amount before accumulated depreciation of building structures held for productive use including addition, improvement, or renovation to the structure, including, but not limited to, interior masonry, interior flooring, electrical, and plumbing.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

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- Definition

Amount of structure or a modification to a structure under construction. Includes recently completed structures or modifications to structures that have not been placed into service.

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- Definition

Amount before accumulated depreciation of equipment commonly used in offices and stores that have no permanent connection to the structure of a building or utilities. Examples include, but are not limited to, desks, chairs, tables, and bookcases.

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- Definition

Amount before accumulated depletion of real estate held for productive use, excluding land held for sale.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef

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- Definition

Amount before accumulated depreciation of tangible personal property used to produce goods and services, including, but is not limited to, tools, dies and molds, computer and office equipment.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

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Amount before accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.

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Amount after accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business to produce goods and services and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

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