Property and Equipment (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012
Property, Plant and Equipment [Line Items]
Property and equipment, net	$ 146,563,000		$ 146,563,000		$ 150,671,000
Depreciation expense	5,300,000	5,300,000	15,800,000	16,000,000
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	271,760,000		271,760,000		265,485,000
Less: accumulated depreciation	(151,928,000)		(151,928,000)		(136,556,000)
Property and equipment, net	119,832,000		119,832,000		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	142,131,000		142,131,000		140,835,000
Dredges and dredging equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	100,142,000		100,142,000		96,927,000
Office equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	4,479,000		4,479,000		4,095,000
Construction in progress
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 11,938,000		$ 11,938,000		$ 6,949,000