Property and Equipment (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2014 acre	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013
Property, Plant and Equipment [Line Items]
Property and equipment, net	$ 163,512,000		$ 163,512,000		$ 141,923,000
Depreciation expense	5,600,000	5,300,000	11,200,000	10,500,000
Area of Property, Plant and Equipment Purchased	340
purchase price of property	22,000,000		22,000,000
Land
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	36,992,000		36,992,000		14,793,000
Depreciable Assets [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	270,699,000		270,699,000		268,793,000
Less: accumulated depreciation	(154,337,000)		(154,337,000)		(144,121,000)
Property and equipment, net	116,362,000		116,362,000		124,672,000
Automobiles and trucks
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	2,048,000		2,048,000		2,148,000
Building and improvements
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	23,058,000		23,058,000		22,828,000
Construction equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	146,632,000		146,632,000		145,309,000
Dredges and dredging equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	94,428,000		94,428,000		93,963,000
Office equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	4,533,000		4,533,000		4,545,000
Construction in progress
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 10,158,000		$ 10,158,000		$ 2,458,000