Concentration of Risk and Enterprise Wide Disclosures Narrative (Details) (Customer concentration risk)	3 Months Ended	12 Months Ended	3 Months Ended
	Mar. 31, 2015	Dec. 31, 2014	Mar. 31, 2014
Trade and contract retainage receivables
Concentration Risk [Line Items]
Concentration risk, percentage	100.00%	100.00%
Contract revenues
Concentration Risk [Line Items]
Concentration risk, percentage	100.00%		100.00%
Private Sector Customer | Trade and contract retainage receivables
Concentration Risk [Line Items]
Concentration risk, percentage	16.20%	14.00%
Private Sector Customer | Contract revenues
Concentration Risk [Line Items]
Concentration risk, percentage			14.30%
U.S. Army Corps of Engineers | Contract revenues
Concentration Risk [Line Items]
Concentration risk, percentage	10.60%		13.80%