Property and Equipment (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Property, Plant and Equipment
Property, plant and equipment, gross	$ 263,383	$ 263,804
Less: accumulated depreciation	(197,330)	(191,542)
Property, plant and equipment net book value of depreciable assets	66,053	72,262
Property and equipment, net	101,774	106,654
Automobiles and trucks
Property, Plant and Equipment
Property, plant and equipment, gross	2,306	2,337
Building and improvements
Property, Plant and Equipment
Property, plant and equipment, gross	36,953	34,796
Construction equipment
Property, Plant and Equipment
Property, plant and equipment, gross	132,268	137,786
Vessels and other equipment
Property, Plant and Equipment
Property, plant and equipment, gross	85,016	82,455
Office equipment
Property, Plant and Equipment
Property, plant and equipment, gross	6,840	6,430
Construction in progress
Property, Plant and Equipment
Property, plant and equipment, gross	7,836	6,507
Land
Property, Plant and Equipment
Property, plant and equipment, gross	$ 27,885	$ 27,885

Property, Plant and Equipment, Net Book Value of Depreciable Assets

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Amount of accumulated depreciation, depletion and amortization for physical assets used in the normal conduct of business to produce goods and services.

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Amount before accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.

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