Segment Information (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023 USD ($) segment	Jun. 30, 2022 USD ($) segment	Jun. 30, 2023 USD ($) segment	Jun. 30, 2022 USD ($) segment	Dec. 31, 2022 USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments | segment	2	2	2	2
Contract revenues	$ 182,534	$ 194,575	$ 341,708	$ 369,506
Operating income (loss)	2,039	(2,848)	(8,604)	(5,703)
Depreciation and amortization			(9,314)	(10,815)
Assets	369,209		369,209		$ 367,155
Property and equipment, net of depreciation	91,793		91,793		$ 100,977
Marine Segment
Segment Reporting Information [Line Items]
Contract revenues	100,543	82,319	179,841	166,799
Marine Segment | Foreign
Segment Reporting Information [Line Items]
Contract revenues	7,300	1,900	10,000	2,600
Concrete Segment
Segment Reporting Information [Line Items]
Contract revenues	81,991	112,256	161,867	202,707
Concrete Segment | Foreign
Segment Reporting Information [Line Items]
Contract revenues	0	0	0	0
Operating Segments | Marine Segment
Segment Reporting Information [Line Items]
Contract revenues	100,543	82,319	179,841	166,799
Operating income (loss)	3,492	2,516	(2,588)	4,356
Depreciation and amortization	(3,812)	(4,236)	(7,647)	(8,559)
Assets	265,913	219,138	265,913	219,138
Property and equipment, net of depreciation	84,251	92,813	84,251	92,813
Operating Segments | Concrete Segment
Segment Reporting Information [Line Items]
Contract revenues	81,991	112,256	161,867	202,707
Operating income (loss)	(1,453)	(5,364)	(6,016)	(10,059)
Depreciation and amortization	(1,531)	(1,862)	(3,142)	(3,802)
Assets	103,296	132,344	103,296	132,344
Property and equipment, net of depreciation	7,542	11,494	7,542	11,494
Intersegment Eliminations
Segment Reporting Information [Line Items]
Contract revenues	$ 0	$ 100		$ 100
Intersegment Eliminations | Maximum
Segment Reporting Information [Line Items]
Contract revenues			$ 100