Property and Equipment (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Property, Plant and Equipment
Property, plant and equipment, gross	$ 265,702	$ 265,359
Less: accumulated depreciation	(209,236)	(206,243)
Property, plant and equipment net book value of depreciable assets	56,466	59,116
Property and equipment, net of depreciation	85,473	87,834
Automobiles and trucks
Property, Plant and Equipment
Property, plant and equipment, gross	1,959	1,985
Building and improvements
Property, Plant and Equipment
Property, plant and equipment, gross	36,931	36,931
Construction equipment
Property, Plant and Equipment
Property, plant and equipment, gross	125,374	125,705
Vessels and other equipment
Property, Plant and Equipment
Property, plant and equipment, gross	94,730	94,030
Office equipment
Property, Plant and Equipment
Property, plant and equipment, gross	6,708	6,708
Construction in progress
Property, Plant and Equipment
Property, plant and equipment, gross	4,059	3,770
Land
Property, Plant and Equipment
Property, plant and equipment, gross	$ 24,948	$ 24,948