Property and Equipment (Details) (USD $)	1 Months Ended	3 Months Ended		9 Months Ended																			1 Months Ended
	Feb. 28, 2014 acre	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013	Sep. 30, 2014 Land	Dec. 31, 2013 Land	Sep. 30, 2014 Depreciable Assets [Member]	Dec. 31, 2013 Depreciable Assets [Member]	Sep. 30, 2014 Automobiles and trucks	Dec. 31, 2013 Automobiles and trucks	Sep. 30, 2014 Building and improvements	Dec. 31, 2013 Building and improvements	Sep. 30, 2014 Construction equipment	Dec. 31, 2013 Construction equipment	Sep. 30, 2014 Dredges and dredging equipment	Dec. 31, 2013 Dredges and dredging equipment	Sep. 30, 2014 Office equipment	Dec. 31, 2013 Office equipment	Sep. 30, 2014 Construction in progress	Dec. 31, 2013 Construction in progress	Sep. 30, 2014 Dry dock
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross							$ 36,992,000	$ 14,793,000	$ 279,666,000	$ 268,793,000	$ 2,061,000	$ 2,148,000	$ 28,413,000	$ 22,828,000	$ 149,432,000	$ 145,309,000	$ 95,329,000	$ 93,963,000	$ 4,431,000	$ 4,545,000	$ 7,680,000	$ 2,458,000
Less: accumulated depreciation									(159,867,000)	(144,121,000)
Property and equipment, net		164,471,000		164,471,000		141,923,000			119,799,000	124,672,000
Depreciation expense		6,300,000	5,300,000	17,500,000	15,800,000
Area of Property, Plant and Equipment Purchased	340
purchase price of property	22,000,000
Payments to acquire property and equipment				$ 18,131,000	$ 11,751,000																		$ 3,500,000