Revenue (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2022 USD ($) segment	Mar. 31, 2021 USD ($) segment
Disaggregation of Revenue [Line Items]
Contract revenues	$ 174,931	$ 153,309
Number of reportable segments | segment	2	2
Marine Segment
Disaggregation of Revenue [Line Items]
Contract revenues	$ 84,480	$ 72,146
Marine Segment | Construction
Disaggregation of Revenue [Line Items]
Contract revenues	59,152	43,936
Marine Segment | Dredging
Disaggregation of Revenue [Line Items]
Contract revenues	22,166	24,682
Marine Segment | Specialty Services
Disaggregation of Revenue [Line Items]
Contract revenues	3,162	3,528
Concrete Segment
Disaggregation of Revenue [Line Items]
Contract revenues	90,451	81,163
Concrete Segment | Structural
Disaggregation of Revenue [Line Items]
Contract revenues	13,676	16,661
Concrete Segment | Light Commercial
Disaggregation of Revenue [Line Items]
Contract revenues	$ 76,775	64,495
Concrete Segment | Other
Disaggregation of Revenue [Line Items]
Contract revenues		$ 7