Amount of estimated earnings in excess of billings as acquired at the acquisition date.

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Amount of liabilities incurred for goods and services received that are used in an entity's business and related party payables, other liabilities assumed at the acquisition date.

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Amount of billings in excess of costs and estimated earnings, assumed at the acquisition date.

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Amount of probable cash flows discount rate.

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The amount of contingent earn-out obligation included in purchase price.

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Period over which contingent earn-out obligation is spread over.

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Amount of consideration transferred, consisting of acquisition-date fair value of assets transferred by the acquirer, liabilities incurred by the acquirer, and equity interest issued by the acquirer.

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Amount of capital lease obligation, assumed at the acquisition date.

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Amount of currency on hand as well as demand deposits with banks or financial institutions, acquired at the acquisition date. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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Amount of other assets expected to be realized or consumed before one year or the normal operating cycle, if longer, acquired at the acquisition date.

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Amount due from customers or clients for goods or services, including trade receivables, that have been delivered or sold in the normal course of business, and amounts due from others, including related parties expected to be converted to cash, sold or exchanged within one year or the normal operating cycle, if longer, acquired at the acquisition date.

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Amount of assets, excluding financial assets and goodwill, that lack physical substance, having a projected indefinite period of benefit, acquired at the acquisition date.

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Amount of other assets expected to be realized or consumed after one year or the normal operating cycle, if longer, acquired at the acquisition date.

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The amount of property, plant, and equipment recognized as of the acquisition date.

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Remaining amortization period of finite-lived intangible assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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The number of businesses acquired by the entity during the period.

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The cash outflow associated with the acquisition of business during the period. The cash portion only of the acquisition price.

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Acquisitions (Details) (USD $)	12 Months Ended	0 Months Ended	12 Months Ended
Acquisitions (Details) (USD $)	Dec. 31, 2013 item	May 01, 2014	Dec. 31, 2014	Dec. 31, 2012
Acquisitions
Number of acquisitions	0us-gaap_NumberOfBusinessesAcquired
Goodwill on acquisition	$ 114,588,000us-gaap_Goodwill		$ 140,341,000us-gaap_Goodwill	$ 114,588,000us-gaap_Goodwill
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets
Goodwill	114,588,000us-gaap_Goodwill		140,341,000us-gaap_Goodwill	114,588,000us-gaap_Goodwill
Dyna Ten
Acquisitions
Goodwill on acquisition		19,379,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets
Cash and cash equivalents		387,000
Receivables		15,516,000
Costs and estimated earnings in excess of billings		1,481,000
Other current assets		601,000
Property and equipment		3,239,000
Other non-current assets		6,000
Goodwill		19,379,000
Identifiable intangible assets		10,900,000
Accounts payable and other current liabilities		(5,634,000)
Billings in excess of costs and estimated earnings		(4,703,000)
Capital lease obligations		(711,000)
Business Combination, Consideration Transferred, Total		40,461,000
Purchase price paid in cash		40,300,000
Contingent earn-out obligation		200,000
Contingent earn-out period		3 years
Minimum estimated milestone payment		0
Maximum estimated milestone payment		2,000,000
Cash flow discount rate		3.00%
Dyna Ten \| Maximum
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets
Cash flow discount rate		16.00%
Dyna Ten \| Minimum
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets
Cash flow discount rate		12.00%
Dyna Ten \| Customer relationships
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets
Identifiable intangible assets		5,600,000
Estimated amortization life		15 years
Dyna Ten \| Backlog
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets
Identifiable intangible assets		1,200,000
Estimated amortization life		2 years
Dyna Ten \| Tradenames
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets
Identifiable intangible assets		4,100,000
Estimated amortization life		25 years
Other Acquisitions
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets
Business Combination, Consideration Transferred, Total			$ 15,400,000	$ 14,200,000