Inventories (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Inventory Disclosure [Abstract]
Raw materials and construction materials	$ 23,330	$ 32,795
Work in process	23,524	19,328
Inventories	$ 46,854	$ 52,123

The aggregate carrying amount, net of valuation reserves and adjustments, as of the balance sheet date of items which are partially completed at the time of measurement and unprocessed items that will go through the production process and become part of the final product. This element may be used when the reporting entity combines work in process and raw materials into an aggregate amount.

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Carrying amount, net of reserves and adjustments, as of the balance sheet date of merchandise or goods which are partially completed. This inventory is generally comprised of raw materials, labor and factory overhead costs, which require further materials, labor and overhead to be converted into finished goods, and which generally require the use of estimates to determine percentage complete and pricing.

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