Property and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 300,601	$ 286,480
Less: accumulated depreciation	(181,293)	(164,371)
Property, Pant and Equipment, Net Book Value of Depreciable Assets	119,308	122,109
Property and equipment, net	158,082	165,989
Automobiles and trucks
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	2,525	2,749
Building and improvements
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	37,269	28,226
Construction equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	165,023	159,963
Dredges and dredging equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	88,659	89,485
Office equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	7,125	6,057
Construction in progress
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	543	5,649
Land
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 38,231	$ 38,231