Property and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 286,480	$ 277,901
Less: accumulated depreciation	(164,371)	(161,276)
Property, Pant and Equipment, Net Book Value of Depreciable Assets	122,109	116,625
Property and equipment, net	165,989	161,773
Automobiles and trucks
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	2,749	2,006
Building and improvements
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	28,226	28,641
Construction equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	159,963	146,088
Dredges and dredging equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	89,485	96,275
Office equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	6,057	4,891
Construction in progress
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	5,649	5,274
Land
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 38,231	$ 39,874