Concentration of Risk and Enterprise Wide Disclosures (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
Concentration Risk [Line Items]
Contract revenues	$ 129,623	$ 81,455
Customer concentration risk \| Trade and contract retainage receivables
Concentration Risk [Line Items]
Trade and retainage receivables	$ 113,145		$ 107,791
Concentration risk, percentage	100.00%		100.00%
Customer concentration risk \| Contract revenues
Concentration Risk [Line Items]
Concentration risk, percentage	100.00%	100.00%
Contract revenues	$ 129,623	$ 81,455
Customer concentration risk \| Federal Government \| Trade and contract retainage receivables
Concentration Risk [Line Items]
Trade and retainage receivables	$ 4,794		$ 4,230
Concentration risk, percentage	4.00%		4.00%
Customer concentration risk \| Federal Government \| Contract revenues
Concentration Risk [Line Items]
Concentration risk, percentage	3.00%	15.00%
Contract revenues	$ 4,156	$ 12,312
Customer concentration risk \| State Governments \| Trade and contract retainage receivables
Concentration Risk [Line Items]
Trade and retainage receivables	$ 812		$ 1,274
Concentration risk, percentage	1.00%		1.00%
Customer concentration risk \| State Governments \| Contract revenues
Concentration Risk [Line Items]
Concentration risk, percentage	4.00%	12.00%
Contract revenues	$ 5,367	$ 9,631
Customer concentration risk \| Local Governments \| Trade and contract retainage receivables
Concentration Risk [Line Items]
Trade and retainage receivables	$ 20,204		$ 19,660
Concentration risk, percentage	18.00%		18.00%
Customer concentration risk \| Local Governments \| Contract revenues
Concentration Risk [Line Items]
Concentration risk, percentage	15.00%	26.00%
Contract revenues	$ 19,677	$ 21,292
Customer concentration risk \| Private Companies \| Trade and contract retainage receivables
Concentration Risk [Line Items]
Trade and retainage receivables	$ 87,335		$ 82,627
Concentration risk, percentage	77.00%		77.00%
Customer concentration risk \| Private Companies \| Contract revenues
Concentration Risk [Line Items]
Concentration risk, percentage	78.00%	47.00%
Contract revenues	$ 100,423	$ 38,220

Trade Accounts Receivable and Contract Receivable Retainage, Net

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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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.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 275
-SubTopic 10
-Section 50
-Paragraph 18
-URI http://asc.fasb.org/extlink&oid=51801978&loc=d3e6351-108592

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 20
-URI http://asc.fasb.org/extlink&oid=49121117&loc=d3e13531-108611

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 275
-SubTopic 10
-Section 50
-Paragraph 20
-URI http://asc.fasb.org/extlink&oid=51801978&loc=d3e6404-108592

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 21
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=49121117&loc=d3e13537-108611

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- Definition

Revenue earned during the period arising from products sold or services provided under the terms of a contract, not elsewhere specified in the taxonomy. May include government contracts, construction contracts, and any other contract related to a particular project or product.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.1)
-URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688

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