Property and Equipment (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012
Property, Plant and Equipment [Line Items]
Property and equipment, net	$ 147,069,000		$ 147,069,000		$ 150,671,000
Depreciation expense	5,200,000	5,300,000	10,500,000	10,700,000
Land
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	14,793,000		14,793,000		14,793,000
Depreciable Assets [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	268,861,000		268,861,000		265,485,000
Less: accumulated depreciation	(146,638,000)		(146,638,000)		(136,556,000)
Property and equipment, net	122,223,000		122,223,000		128,929,000
Automobiles and trucks
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	2,180,000		2,180,000		1,591,000
Building and improvements
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	22,828,000		22,828,000		22,037,000
Construction equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	141,218,000		141,218,000		140,835,000
Dredges and dredging equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	98,240,000		98,240,000		96,927,000
Office equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	4,395,000		4,395,000		4,095,000
Construction in progress
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 10,053,000		$ 10,053,000		$ 6,949,000