Inventories (Inventories) (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Inventory Disclosure [Abstract]
Raw materials and construction materials	$ 22,664	$ 23,239
Work in process	14,339	14,306
Inventories	$ 37,003	$ 37,545

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.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 330
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SAB TOPIC 5.BB)
-URI http://asc.fasb.org/extlink&oid=27011343&loc=d3e100047-122729

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.6(a)(3),(4))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Staff Accounting Bulletin (SAB)
-Number Topic 5
-Section BB

Name:	us-gaap_InventoryWorkInProcessAndRawMaterialsNetOfReserves
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant