Property and Equipment (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Property, Plant and Equipment
Property, plant and equipment, gross	$ 262,956	$ 268,224
Less: accumulated depreciation	(198,704)	(195,948)
Property, plant and equipment net book value of depreciable assets	64,252	72,276
Property and equipment, net of depreciation	91,793	100,977
Automobiles and trucks
Property, Plant and Equipment
Property, plant and equipment, gross	2,089	2,232
Building and improvements
Property, Plant and Equipment
Property, plant and equipment, gross	36,953	36,952
Construction equipment
Property, Plant and Equipment
Property, plant and equipment, gross	127,924	130,660
Vessels and other equipment
Property, Plant and Equipment
Property, plant and equipment, gross	89,051	91,495
Office equipment
Property, Plant and Equipment
Property, plant and equipment, gross	6,939	6,885
Construction in progress
Property, Plant and Equipment
Property, plant and equipment, gross	2,593	816
Land
Property, Plant and Equipment
Property, plant and equipment, gross	$ 24,948	$ 27,885