Property and Equipment (Details) (USD $)	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012
Property, Plant and Equipment [Line Items]
Property and equipment, net	$ 148,094,000		$ 150,671,000
Depreciation expense	5,300,000	5,400,000
Land
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	14,793,000		14,793,000
Depreciable Assets [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	266,295,000		265,485,000
Less: accumulated depreciation	(141,768,000)		(136,556,000)
Property and equipment, net	124,527,000		128,929,000
Automobiles and trucks
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	2,180,000		1,591,000
Building and improvements
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	22,828,000		22,037,000
Construction equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	140,115,000		140,835,000
Dredges and dredging equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	96,927,000		96,927,000
Office equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	4,245,000		4,095,000
Construction in progress
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 8,774,000		$ 6,949,000