Increase in gross margin percentage recognized as a result of revised cost estimates.

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Represents the amount of deductible under health insurance benefits for qualified individuals.

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Represents the percentage of retainage of long-term contracts recorded and expected to be collected by the entity within one year.

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Amount charged to advertising expense for the period, which are expenses incurred with the objective of increasing revenue for a specified brand, product or product line.

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For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

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The amount of net income (loss) for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

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Amount before tax of foreign currency transaction realized gain (loss) recognized in the income statement.

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The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

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Organization, Business and Significant Accounting Policies (Details Textual) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Organization Consolidation and Presentation of Financial Statements [Line Items]
Operating Income (Loss)									$ 44,841	$ 58,404	$ 55,617
Net Income (Loss) Attributable to Parent	$ 5,881	$ 6,175	$ 8,074	$ 7,172	$ 14,127	$ 8,404	$ 7,741	$ 6,272	$ 27,302	$ 36,544	$ 34,759
Earnings Per Share, Diluted	$ 0.29	$ 0.29	$ 0.38	$ 0.34	$ 0.66	$ 0.39	$ 0.36	$ 0.29	$ 1.30	$ 1.69	$ 1.61
Advertising Expense									$ 500	$ 400	$ 300
Percentage Of Retainage Recorded And Collected Within One Year									90.00%
Loss Contingency Insurance Policy Deductible for Each Line of Coverage Excluding Health	$ 1,000								$ 1,000
Loss Contingency Health Insurance Deductible For Qualified Individuals	$ 100								100
Foreign Currency Transaction Gain (Loss), Realized									300
Additional Paid-in Capital [Member]
Organization Consolidation and Presentation of Financial Statements [Line Items]
Net Income (Loss) Attributable to Parent									0	0	0
Prior Period Reclassification Adjustment									14,000
Retained Earnings [Member]
Organization Consolidation and Presentation of Financial Statements [Line Items]
Net Income (Loss) Attributable to Parent									27,302	$ 36,544	$ 34,759
Prior Period Reclassification Adjustment									$ 14,000
Accounts Receivable [Member] \| Number of Customers [Member]
Organization Consolidation and Presentation of Financial Statements [Line Items]
Concentration Risk, Percentage									10.00%	10.00%
Accounts Receivable [Member] \| Number of Customers [Member] \| Credit Concentration Risk [Member]
Organization Consolidation and Presentation of Financial Statements [Line Items]
Concentration Risk, Percentage									13.00%	14.20%
Number Of Customers Individually Exceeding Ten Percent Consolidated Accounts Receivable									1	1
Revenues [Member] \| Number of Customers [Member] \| Customer concentration risk [Member]
Organization Consolidation and Presentation of Financial Statements [Line Items]
Concentration Risk, Percentage									10.00%	10.00%	10.00%
Revenues [Member] \| Top Ten Customers [Member] \| Customer concentration risk [Member]
Organization Consolidation and Presentation of Financial Statements [Line Items]
Concentration Risk, Percentage									44.60%	46.50%	57.80%
Labor employees covered by collective bargaining agreements [Member] \| Labor Force Concentration Risk [Member]
Organization Consolidation and Presentation of Financial Statements [Line Items]
Concentration Risk, Percentage									91.00%
Contracts Accounted for under Percentage of Completion [Member] \| Cost Estimate Revision [Member]
Organization Consolidation and Presentation of Financial Statements [Line Items]
Cost Estimate Revision Gross Margin Increase Percentage									0.50%	1.90%	0.80%
Estimate Adjustment [Member]
Organization Consolidation and Presentation of Financial Statements [Line Items]
Operating Income (Loss)									$ 5,900	$ 18,400	$ 7,700
Net Income (Loss) Attributable to Parent									$ 3,600	$ 11,600	$ 4,900
Earnings Per Share, Diluted									$ 0.17	$ 0.54	$ 0.23