Property and Equipment (Details) (USD $)	3 Months Ended
	Mar. 31, 2014 acre	Mar. 31, 2013	Dec. 31, 2013
Property, Plant and Equipment [Line Items]
Property and equipment, net	$ 160,455,000		$ 141,923,000
Depreciation expense	5,600,000	5,300,000
Area of Property, Plant and Equipment Purchased	340
purchase price of property	22,000,000
Land
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	36,992,000		14,793,000
Depreciable Assets [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	269,444,000		268,793,000
Less: accumulated depreciation	(149,403,000)		(144,121,000)
Property and equipment, net	120,041,000		124,672,000
Automobiles and trucks
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	2,038,000		2,148,000
Building and improvements
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	22,828,000		22,828,000
Construction equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	145,770,000		145,309,000
Dredges and dredging equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	93,889,000		93,963,000
Office equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	4,919,000		4,545,000
Construction in progress
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 3,422,000		$ 2,458,000