Revenue (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2025 USD ($) segment	Mar. 31, 2024 USD ($) segment
Disaggregation of Revenue [Line Items]
Contract revenues	$ 188,653	$ 160,672
Number of reportable segments | segment	2	2
Marine
Disaggregation of Revenue [Line Items]
Contract revenues	$ 127,163	$ 106,325
Marine | Construction
Disaggregation of Revenue [Line Items]
Contract revenues	104,482	88,789
Marine | Dredging
Disaggregation of Revenue [Line Items]
Contract revenues	16,911	14,670
Marine | Specialty Services
Disaggregation of Revenue [Line Items]
Contract revenues	5,770	2,866
Concrete
Disaggregation of Revenue [Line Items]
Contract revenues	61,490	54,347
Concrete | Structural
Disaggregation of Revenue [Line Items]
Contract revenues	13,721	11,573
Concrete | Light Commercial
Disaggregation of Revenue [Line Items]
Contract revenues	$ 47,769	$ 42,774