Concentration of Risk and Enterprise Wide Disclosures (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended							6 Months Ended	12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Mar. 31, 2012	Jun. 30, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Concentration Risk [Line Items]
Contract revenues	$ 106,412	$ 88,992	$ 84,081	$ 75,059	$ 98,634	$ 75,386	$ 50,890	$ 67,132	$ 354,544	$ 292,042	$ 259,852
Foreign
Concentration Risk [Line Items]
Contract revenues, percent									8.50%	4.00%	1.00%
Customer concentration risk | Trade and contract retainage receivables
Concentration Risk [Line Items]
Trade and retainage receivables	49,537				53,285				49,537	53,285
Concentration risk, percentage									100.00%		100.00%
Customer concentration risk | Contract revenues
Concentration Risk [Line Items]
Concentration risk, percentage									100.00%	100.00%	100.00%
Contract revenues									354,544	292,042	259,852
Customer concentration risk | US Army Corps of Engineers | Trade and contract retainage receivables
Concentration Risk [Line Items]
Concentration risk, percentage							9.10%
Customer concentration risk | US Army Corps of Engineers | Contract revenues
Concentration Risk [Line Items]
Concentration risk, percentage							16.70%		11.70%		24.00%
Customer concentration risk | Private sector customer | Trade and contract retainage receivables
Concentration Risk [Line Items]
Concentration risk, percentage							12.50%		9.90%
Customer concentration risk | Private sector customer | Contract revenues
Concentration Risk [Line Items]
Concentration risk, percentage										10.70%
Customer concentration risk | Federal Government | Trade and contract retainage receivables
Concentration Risk [Line Items]
Trade and retainage receivables	4,849				7,375				4,849	7,375
Concentration risk, percentage									10.00%		14.00%
Customer concentration risk | Federal Government | Contract revenues
Concentration Risk [Line Items]
Concentration risk, percentage									19.00%	22.00%	42.00%
Contract revenues									65,926	64,049	108,123
Customer concentration risk | State Governments | Trade and contract retainage receivables
Concentration Risk [Line Items]
Trade and retainage receivables	4,002				1,761				4,002	1,761
Concentration risk, percentage									8.00%		3.00%
Customer concentration risk | State Governments | Contract revenues
Concentration Risk [Line Items]
Concentration risk, percentage									9.00%	12.00%	19.00%
Contract revenues									30,451	35,799	48,604
Customer concentration risk | Local Governments | Trade and contract retainage receivables
Concentration Risk [Line Items]
Trade and retainage receivables	8,857				5,532				8,857	5,532
Concentration risk, percentage									18.00%		11.00%
Customer concentration risk | Local Governments | Contract revenues
Concentration Risk [Line Items]
Concentration risk, percentage									15.00%	15.00%	15.00%
Contract revenues									54,702	44,626	40,647
Customer concentration risk | Private Companies | Trade and contract retainage receivables
Concentration Risk [Line Items]
Trade and retainage receivables	31,829				38,617				31,829	38,617
Concentration risk, percentage									64.00%		72.00%
Customer concentration risk | Private Companies | Contract revenues
Concentration Risk [Line Items]
Concentration risk, percentage									57.00%	51.00%	24.00%
Contract revenues									$ 203,465	$ 147,568	$ 62,478