Property, Plant and Equipment (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Property, Plant and Equipment
Buildings	$ 15,126	$ 15,130
Machinery and equipment	87,127	71,550
Seismic rental equipment	10,895	2,986
Furniture and fixtures	3,403	3,377
Other	3,857	1,727
Total	120,408	94,770
Less accumulated depreciation	(86,636)	(69,999)
Property, plant, equipment and seismic rental equipment net	$ 33,772	$ 24,771

The cumulative amount of depreciation, depletion and amortization (related to property, plant and equipment, but not including land) that has been recognized in the income statement.

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Gross amount of long-lived 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, furniture and fixtures, and computer equipment.

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- Definition

Amount, net of accumulated depreciation, depletion and amortization, of long-lived 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, furniture and fixtures, and computer equipment.

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