Percentage of increase decrease cost estimate revision gross margin.

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

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Represents the amount of deductible up to the claim aggregate under insurance arrangements, for each line of coverage excluding auto liability and medical insurance, excluding health insurance.

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- Definition

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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- Definition

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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- Definition

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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The net result for the period of deducting operating expenses from operating revenues.

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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, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Organization Consolidation and Presentation of Financial Statements [Line Items]
Operating Income (Loss)									$ 38,754	$ 44,841	$ 58,404
Net Income (Loss) Attributable to Parent	$ 7,798	$ 6,146	$ 5,500	$ 1,987	$ 5,881	$ 6,175	$ 8,074	$ 7,172	$ 21,431	$ 27,302	$ 36,544
Earnings Per Share, Diluted	$ 0.48	$ 0.38	$ 0.31	$ 0.10	$ 0.29	$ 0.29	$ 0.38	$ 0.34	$ 1.23	$ 1.3	$ 1.69
Advertising Expense									$ 600	$ 500	$ 400
Loss Contingency Insurance Policy Deductible for Each Line of Coverage Excluding Health	$ 1,000								1,000
Foreign Currency Transaction Gain (Loss), Realized									200
Maximum [Member]
Organization Consolidation and Presentation of Financial Statements [Line Items]
Loss Contingency Health Insurance Deductible For Qualified Individuals	$ 200								$ 200
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									11.20%	13.00%
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									46.40%	44.60%	46.50%
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 (Decrease) Percentage									(0.20%)	0.50%	1.90%
Estimate Adjustment [Member]
Organization Consolidation and Presentation of Financial Statements [Line Items]
Operating Income (Loss)									$ (2,600)	$ 5,900	$ 18,400
Net Income (Loss) Attributable to Parent									$ (1,400)	$ 3,600	$ 11,600
Earnings Per Share, Diluted									$ (0.08)	$ 0.17	$ 0.54