Revenue (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022 USD ($) segment	Jun. 30, 2021 USD ($) segment	Jun. 30, 2022 USD ($) segment	Jun. 30, 2021 USD ($) segment
Disaggregation of Revenue [Line Items]
Contract revenues	$ 194,575	$ 145,875	$ 369,506	$ 299,184
Number of reportable segments | segment	2	2	2	2
Marine Segment
Disaggregation of Revenue [Line Items]
Contract revenues	$ 82,319	$ 63,942	$ 166,799	$ 136,088
Marine Segment | Construction
Disaggregation of Revenue [Line Items]
Contract revenues	53,210	38,859	112,362	82,795
Marine Segment | Dredging
Disaggregation of Revenue [Line Items]
Contract revenues	24,320	20,672	46,486	45,354
Marine Segment | Specialty Services
Disaggregation of Revenue [Line Items]
Contract revenues	4,789	4,411	7,951	7,939
Concrete Segment
Disaggregation of Revenue [Line Items]
Contract revenues	112,256	81,933	202,707	163,096
Concrete Segment | Structural
Disaggregation of Revenue [Line Items]
Contract revenues	17,864	17,545	31,540	34,206
Concrete Segment | Light Commercial
Disaggregation of Revenue [Line Items]
Contract revenues	$ 94,392	$ 64,388	$ 171,167	128,883
Concrete Segment | Other
Disaggregation of Revenue [Line Items]
Contract revenues				$ 7