Segment Information (Details)	3 Months Ended		6 Months Ended
	Jun. 30, 2024 USD ($) segment	Jun. 30, 2023 USD ($) segment	Jun. 30, 2024 USD ($) segment	Jun. 30, 2023 USD ($) segment	Dec. 31, 2023 USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments | segment	2	2	2	2
Contract revenues	$ 192,167,000	$ 182,534,000	$ 352,839,000	$ 341,708,000
Operating income (loss)	(2,768,000)	2,039,000	(5,892,000)	(8,604,000)
Depreciation and amortization			(8,326,000)	(9,314,000)
Assets	414,019,000		414,019,000		$ 416,893,000
Property and equipment, net of depreciation	85,975,000		85,975,000		$ 87,834,000
Marine
Segment Reporting Information [Line Items]
Contract revenues	130,953,000	100,543,000	237,278,000	179,841,000
Marine | Foreign
Segment Reporting Information [Line Items]
Contract revenues	16,500,000	7,300,000	26,000,000.0	10,000,000.0
Concrete
Segment Reporting Information [Line Items]
Contract revenues	61,214,000	81,991,000	115,561,000	161,867,000
Concrete | Foreign
Segment Reporting Information [Line Items]
Contract revenues	0	0	0	0
Operating Segments | Marine
Segment Reporting Information [Line Items]
Contract revenues	130,953,000	100,543,000	237,278,000	179,841,000
Operating income (loss)	(5,466,000)	3,492,000	(10,332,000)	(2,588,000)
Depreciation and amortization	(4,922,000)	(3,812,000)	(9,853,000)	(7,647,000)
Assets	322,031,000	265,913,000	322,031,000	265,913,000
Property and equipment, net of depreciation	80,115,000	84,251,000	80,115,000	84,251,000
Operating Segments | Concrete
Segment Reporting Information [Line Items]
Contract revenues	61,214,000	81,991,000	115,561,000	161,867,000
Operating income (loss)	2,698,000	(1,453,000)	4,440,000	(6,016,000)
Depreciation and amortization	(1,048,000)	(1,531,000)	(2,137,000)	(3,142,000)
Assets	91,988,000	103,296,000	91,988,000	103,296,000
Property and equipment, net of depreciation	5,860,000	7,542,000	5,860,000	7,542,000
Intersegment Eliminations
Segment Reporting Information [Line Items]
Contract revenues	$ 1,100,000	$ 0	$ 1,700,000	$ 100,000