Concentration of Risk and Enterprise Wide Disclosures (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Concentration Risk [Line Items]
Contract revenues	$ 98,634	$ 75,386	$ 67,132	$ 50,890	$ 55,313	$ 54,583	$ 70,899	$ 79,057	$ 292,042	$ 259,852	$ 353,135
Foreign
Concentration Risk [Line Items]
Contract revenues, percent									4.00%	1.00%	5.00%
Customer concentration risk | Trade and contract retainage receivables
Concentration Risk [Line Items]
Trade and retainage receivables	53,285				26,931				53,285	26,931
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									292,042	259,852	353,135
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%	24.00%	28.00%
Customer concentration risk | Private sector customer | Trade and contract retainage receivables
Concentration Risk [Line Items]
Concentration risk, percentage									11.70%	12.50%
Customer concentration risk | Private sector customer | Contract revenues
Concentration Risk [Line Items]
Concentration risk, percentage									10.70%		9.80%
Customer concentration risk | Second private sector customer | Trade and contract retainage receivables
Concentration Risk [Line Items]
Concentration risk, percentage									9.90%
Customer concentration risk | Federal Government | Trade and contract retainage receivables
Concentration Risk [Line Items]
Trade and retainage receivables	7,375				5,958				7,375	5,958
Concentration risk, percentage									14.00%	22.00%
Customer concentration risk | Federal Government | Contract revenues
Concentration Risk [Line Items]
Concentration risk, percentage									22.00%	42.00%	41.00%
Contract revenues									64,049	108,123	143,697
Customer concentration risk | State Governments | Trade and contract retainage receivables
Concentration Risk [Line Items]
Trade and retainage receivables	1,761				379				1,761	379
Concentration risk, percentage									3.00%	1.00%
Customer concentration risk | State Governments | Contract revenues
Concentration Risk [Line Items]
Concentration risk, percentage									12.00%	19.00%	11.00%
Contract revenues									35,799	48,604	40,145
Customer concentration risk | Local Governments | Trade and contract retainage receivables
Concentration Risk [Line Items]
Trade and retainage receivables	5,532				6,207				5,532	6,207
Concentration risk, percentage									10.00%	24.00%
Customer concentration risk | Local Governments | Contract revenues
Concentration Risk [Line Items]
Concentration risk, percentage									15.00%	15.00%	12.00%
Contract revenues									44,626	40,647	41,868
Customer concentration risk | Private Companies | Trade and contract retainage receivables
Concentration Risk [Line Items]
Trade and retainage receivables	38,617				14,387				38,617	14,387
Concentration risk, percentage									73.00%	53.00%
Customer concentration risk | Private Companies | Contract revenues
Concentration Risk [Line Items]
Concentration risk, percentage									51.00%	24.00%	36.00%
Contract revenues									$ 147,568	$ 62,478	$ 127,425