Property and Equipment (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 285,043	$ 286,480
Less: accumulated depreciation	(167,143)	(164,371)
Net book value of depreciable assets	117,900	122,109
Property and equipment, net	166,011	165,989
Automobiles and trucks
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	2,506	2,749
Building and improvements
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	28,302	28,226
Construction equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	162,857	159,963
Vessels and other equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	85,133	89,485
Office equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	6,245	6,057
Construction in progress
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	9,880	5,649
Land
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 38,231	$ 38,231